Tuesday, November 19, 2019
Italy's invasion of Ethiopia in 1935 Research Paper
Italy's invasion of Ethiopia in 1935 - Research Paper Example It will identify the military tactics used by both sides and comment on the outcome of the conflict. Finally it will analyze the consequences of the military conflict. Causes Italy had been a latecomer in the scramble for colonies as compared with other European powers. During the 1920s, it had signed a friendship treaty with Ethiopia which called for mutual respect and peace across the borders. However, the Mussolini regime sought to consolidate its power in the Horn of Africa. Ethiopia was a natural target due to its huge size and resources (Gooch, 45). In addition, the Italians wanted to avenge their humiliating defeat at the Battle of Adowa in 1896 at the hands of the Ethiopian armies. The immediate cause for the conflict was a series of border disputes in Italian Somaliland. Italy had established a military garrison in the Welwel oasis which was considered to be Ethiopian territory. Subsequently in December 1934, a military clash broke out between Ethiopian and Italian forces in the â€Å"Wal Wal incident†(Gooch, 45). These border disputes were not handled in an efficient manner by the League of Nations. The UK and France remained passive in the wake of Italian provocations. This emboldened Italy to initiate a war against Ethiopia on October 1935. Military Tactics The Italians enjoyed complete military superiority over the poorly armed Ethiopians. The goal of the Italians was to use overwhelming force through the application of modern weapons like warplanes, artillery, tanks, and missiles. The Italians used combined arms operations that comprised of infantry which was supported by armor and airpower. This shocking power decimated entire Ethiopian armies (Mockler, 93). The Italians also used poison gas as a means of terrorizing and demoralizing the defenders. Civilians were killed and the natural environment was decimated through the use of poison gas. The Italian army was considered to be relatively inexperienced when compared with other Western ar mies. Its advance into Ethiopia was remarkably slow despite its inherent military superiority. The Ethiopians were able to stall the advance for six months before being overwhelmed by superior technology. Despite their inferior weapons, they were able to utilize the terrain and numerical strength to isolate and destroy Italian columns in several actions. The Ethiopians sought to drag the Italians into a bloody war of attrition. They sought to use guerillas in order to harass Italian military units behind their flanks and supply lines. Haile Selassie sought to use the Imperial Guard, the best trained armies, for driving a wedge between the main Italian armies. It was argued that the Ethiopians would avoid set piece battles and resort to guerilla warfare. Conventional war would be conducted only on favorable terms in order to neutralize the military superiority of Italy (Nicolle, 92). Casualties and Outcome It is estimated that over 10,000 Italians and 275,000 Ethiopians were killed i n the conflict. Over 44,000 Italians and 500,000 Ethiopians were wounded in the military conflict (Nicolle, 123). The Italians would win the war by defeating the Ethiopians after six months of battles. The occupation of Ethiopia would last until the liberation of the territory by the Allied forces. Ethiopian guerillas would continue to wage resistance against the occupying forces. Important Battles and Events Emperor Haile Selassie launched the â€Å"Christmas Offensive†as a counterattack against the advancing Italian forces.
Sunday, November 17, 2019
My professional and academic goals related to wardens school of nursing Essay Example for Free
My professional and academic goals related to wardens school of nursing Essay My Professional and Academic Goals related to Waldens School of Nursing Perspectives I have been a nurse for 14 years, mostly in the Emergency Department, and have become aware of the growing population and the need for Family Nurse Practitioners (FNP’s). According to Walden’s University Catalog (DEC. 2013a), FNP’s are defined as â€Å"advanced practice registered nurses with the knowledge and skills to assess and manage health issues in patients of all age groups, from birth through senior years. †My goal as a FNP is to provide advanced health care with a holistic approach including: disease prevention, health maintenance, health promotion, restorative care, and a positive social change. I have chosen Walden University through high recommendations from my colleagues. They have enlightened me on the positive impact Walden School of Nursing has made in their personal and professional careers. Walden’s vision and mission statement reinforced my decision to become a part of the Walden Family Nurse Practitioner School of Nursing. According to Walden University Catalog (DEC. 2013b) their vision is focused on a distinctive different 21st –century learning community that provides immediate solutions of critical societal challenges and advancing global good. My vision agrees that healthcare professionals need to focus on advanced 21st century technology and the societal challenges that arise and promote a positive social change. Walden University Catalog (DEC.2013b) defines positive social change â€Å"as a deliberate process of creating and applying ideas, strategies, and actions to promote the worth, dignity, and development of individuals, communities, organizations, institutions, cultures, and societies. Positive social change results in the improvement of human and social conditions. †I plan to implement social change with the knowledge and education that the Walden School of Nursing provides while supporting and recognizing the many cultures in the community.
Thursday, November 14, 2019
the crime :: essays research papers
                                             Chad                                    â€Å"The Bahamas,†it was a trip of a lifetime. I went there with my girlfriend and a couple of other friends. We were all nervous because it was the first time any of us have flown. We finally got a chance to start boarding, after we arrived at the airport five hours early. Before boarding, we had to show the airport attendants our birth certificate. When I went to show them my birth certificate, they wouldn’t let me board because mine was a copy and not the original. Luckily, after waiting for twenty minutes, they made a few calls and let me go.      As we flew over the ocean the water was crystal clear and the sky was beautiful. I couldn’t wait to get there, but after two and a half hours, we finally arrived in Nassau, Bahamas. We got off the plane and the weather was beautiful, it was 90 degrees and sunny. We walked in, got our luggage and had to go through customs. We went outside caught our bus and off we went to our resort. When arrived there everyone was very nice and respectful.      Our first day their we planned to take a boat over to the Atlantis resort on Paradise, Island. The Atlantis is a resort known to have movie stars and athletes stay. I was only twenty years old when we went there, so I have never been to a casino. We all got to gamble, and I won $300 playing blackjack, it was a blast. The resort also had an underground aquarium with sharks and lots of other odd looking fish.      The next few days we sat around the resort and went parasailing, and lots of other activities. Parasailing was an adrenaline rush and probably one of the funnier things I had done in my life. We also went downtown Nassau and that is where they have a big flea market. The flea market had a lot of neat and different things down there. We spent the whole day downtown and later that night went out to a few dance clubs.      The last two days we were there a hurricane was roaring in, while we were trying to get out.
Tuesday, November 12, 2019
Grignard Reagent
1598 Organometallics 2009, 28, 1598–1605 CoVer Essay The Grignard Reagents Dietmar Seyferth Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 ReceiVed February 4, 2009 During the past 100 years the Grignard reagents probably have been the most widely used organometallic reagents. Most of them are easily prepared in ethereal solution (usually diethyl ether or, since the early 1950s, THF) by the reaction of an organic halide with metallic magnesium (eq 1).Table 1. Composition of Diethyl Ether Solutions of Various Grignard Reagents at Equilibrium (in mol %), 2RMgX h R2Mg + MgX2a RX in RX + Mg reacn CH3I C2H5I C2H5Br C2H5Cl n-C3H7I n-C3H7Br n-C3H7Cl C6H5I C6H5Br a RMgX 87. 0 43. 0 41. 0 15. 0 24. 0 24. 0 17. 0 38. 0 30. 0 R2Mg ) MgX2 6. 5 28. 5 29. 5 42. 5 38. 0 38. 0 41. 5 31. 0 35. 0 RX + Mg f RMgX (X ) Cl, Br, I) (1) Most of them are stable in ethereal solution (although atmospheric moisture and oxygen should be excluded) and in gene ral are quite reactive.Discovered by Victor Grignard at the University of Lyon in France in 1900,1 their ease of preparation and their broad applications in organic and organometallic synthesis made these new organomagnesium reagents an instant success. The importance of this contribution to synthetic chemistry was recognized very early, and for his discovery Grignard was awarded a Nobel Prize in Chemistry in 1912. Our cover molecule is the monomeric ethylmagnesium bromide bis(diethyl etherate) (1), whose solid-state molecular structure was determined by an X-ray diffraction study by Lloyd Guggenberger and RobertRundle in 1964 using crystals isolated from a diethyl ether solution of a C2H5Br/Mg reaction mixture by slow cooling with a stream of cold gaseous nitrogen. 2-4 Adapted from: Schlenk, W. , Jr. Ber. Dtsch. Chem. Ges. 1931, 64, 734. Wilhelm Schlenk and his son discovered 80 years ago, more than one magnesium-containing species exists in the diethyl ether solution of a Grignard reagent. 5 A redistribution of the substituents on magnesium takes place, and the RMgX species ends up in equilibrium with the two symmetrical species, the diorganomagnesium and the magnesium dihalide: the â€Å"Schlenk Equilibrium†(eq 2). 2RMgX h R2Mg + MgX2 (2) Generally written as â€Å"RMgX†in textbooks, monographs and research papers, the Grignard reagents in ethereal solution are more complicated than this simple formula indicates. As (1) (a) Grignard, V. Compt. rend. Hebd. Seances Acad. Sci. 1900, 130, ? 1322. (b) Grignard, V. Dissertation â€Å"Theses sur les combinaisons organo` magnesienes mixtes et leur application a des syntheses†, University of Lyon, ` ` Lyon, France, 1901. (2) (a) Guggenberger, L. J. ; Rundle, R. E. J. Am. Chem. Soc. 1964, 86, 5344. (b) Guggenberger, L. J. ; Rundle, R. E. J. Am. Chem. Soc. 1968, 90, 5375. 3) A crystalline solid, CH3MgI  · (n-C5H11)2O, was isolated and identi? ed as such by elemental analysis (Mg and I) in 1908 : Zerewitinoff, Th. Ber. Dtsch. Chem. Ges. 1908, 41, 2244. The oxonium structure The species that contain Mg-halogen bonds can be precipitated from Grignard reagent solutions in diethyl ether by the addition of 1,4-dioxane. An insoluble, polymeric 1,4-dioxane adduct is formed, leaving behind a solution of R2Mg5sa useful preparation of dialkyl- and diarylmagnesium reagents. 6 Wilhelm Schlenk, Jr. analyzed the 1,4-dioxane precipitations from a number of Grignard reagent solutions. Assuming that the precipitation is essentially instantaneous, i. e. , that the calculated R2Mg, MgX2, and RMgX percentages re? ect the actual composition of the Grignard reagent solution at equilibrium, Schlenk reported the compositions collected in Table 1. Direct evidence (5) Schlenk, W. ; Schlenk, W. , Jr. Ber. Dtsch. Chem. Ges. 1929, 62, 920. (6) (a) Cope, A. C. J. Am. Chem. Soc. 1935, 57, 2238. (b) As Erwin Weiss found, evaporation of diethyl ether solutions of methyl- and ethylmagnesium bromide and chl oride at reduced pressure followed by heating of the colorless solid residues at ca. 00  °C and 0. 001 mmHg for several hours gave a mixture of the respective pure, solvent-free, polymeric R2Mg compounds and magnesium halides. The solid MgCl2 thus obtained differed from a sample obtained from a MgCl2 melt in that its lattice showed a strong stacking disorder. This form of MgCl2 had an extremely high surface area: Weiss, E. Chem. Ber. 1965, 98, 2805. (7) Schlenk, W. , Jr. Ber. Dtsch. Chem. Ges. 1931, 64, 734 Further additions to the examples in Table 1 were soon thereafter reported by other workers: (a) Noller, C. R. ; Hilmer, F. B. J. Am. Chem. Soc. 1932, 54, 2503. (b) Johnson, G. O. Adkins, H. J. Am. Chem. Soc. 1932, 54, 1943. (c) Cope, A. C. J. Am. Chem. Soc. 1934, 56, 1578. was written for this compound. Earlier workers had isolated noncrystalline solid samples of etherates, e. g. , C2H5MgI  · (C2H5)2O and RMgI  · 2(C2H5)2O. (4) Other early Grignard reagent crystal structur es: (a) Stucky, G. D. ; Rundle, R. E. J. Am. Chem. Soc. 1964, 86, 4825 (C6H5MgBr  · 2Et2O). (b) Vallino, M. J. Organomet. Chem. 1969, 20, 1 (CH3MgBr  · 3THF). . 10. 1021/om900088z CCC: $40. 75 ? 2009 American Chemical Society Publication on Web 03/16/2009 Organometallics, Vol. 28, No. 6, 2009 1599 Figure 1.Association of several Grignard compounds in tetrahydrofuran (J. Am. Chem. Soc. 1969, 91, 3847. ). that solutions of â€Å"CH3MgBr†in diethyl ether contain CH3MgBr and (CH3)2Mg was obtained by Ashby and co-workers by means of 1H NMR spectroscopic measurements at -105  °C. Solutions of â€Å"t-butylmagnesium chloride†in diethyl ether also were studied. 8 The tendency of the halide substituents in the RMgX and MgX2 species present in ethereal solution at equilibrium to form bridges between magnesium atoms, Mg-X-Mg, in a Lewis base/Lewis acid type interaction further complicates the nature of the Grignard reagent in ethereal solvents.In a very thorough study of the association factors of various Grignard reagents in diethyl ether and THF by careful ebullioscopic molecular weight measurements, Eugene Ashby and Frank Walker at the Georgia Institute of Technology found that monomeric, dimeric, and higher oligomeric species were present, depending on the solvent and the halogen and the organic substituents on the magnesium atom. 9 Included in this study along with data for the â€Å"RMgX†solutions were data for a few R2Mg compounds and for the magnesium dihalides.As Figure 1 shows, the observed association factor (the i value is the apparent molecular weight divided by the formula weight of the monoetherate) shows that the Grignard reagents and (C6H5)2Mg are close to monomeric in the relatively strong Lewis basic THF. The picture is quite different in diethyl ether solution (Figures 2 and 3), with association factors of 1 to nearly 4 for solute concentrations up to ca. 3 molal. It is not clear what these i values mean in terms of the a ctual species present in these solutions.On the assumption that the Schlenk equilibrium is operative in all cases, in view of the presence of a signi? cant concentration of MgX2, one cannot expect only simple solvated species of type i(R)Mg-X] n [ i (average n ) i). Toney and Stucky isolated crystals of a dimeric species, 2, from a solution of â€Å"C2H5MgBr†in di-n-butyl ether by addition of this solution to triethylamine. 10 The molecular Figure 2. Association of alkylmagnesium chlorides in diethyl ether. Demonstration of importance of halogen vs R group in determining the form of association in diethyl ether (J. Am. Chem. Soc. 1969, 91, 3848. ).Figure 3. Association of several alkyl- and arylmagnesium bromides and iodides and related magnesium compounds in diethyl ether (J. Am. Chem. Soc. 1969, 91, 3848. ). structure, as determined by X-ray analysis, contained a double Br bridge with the ethyl groups in a trans arrangement. That (8) In â€Å"CH3MgBr†solutions in d iethyl ether: (a) Ashby, E. C. ; Parrish, G. ; Walker, F. Chem. Commun. 1969, 1464. (b) â€Å"(CH3)3CMgCl†solutions in diethyl ether at-26  °C: Parris, G. ; Ashby, E. C. J. Am. Chem. Soc. 1971, 93, 1206. (9) (a) Walker, F. W. ; Ashby, E. C. J. Am. Chem. Soc. 1969, 91, 3845. (b) Ashby, E. C. Bull. Soc.Chim. Fr. 1972, 2133 (review, in English). (c) Meisenheimer, J. ; Schlichenmaier. Ber. Dtsch. Chem. Ges. 1928, 61 (an earlier, similar, but more limited study in diethyl ether). more complicated structures can be present in an â€Å"RMgX†solution in diethyl ether was demonstrated by the determination of the X-ray crystal structure of a crystalline compound obtained from a THF solution of â€Å"C2H5MgCl†of composition C2H5Mg2Cl3. This compound was not a simple Cl-bridged dimer, as the empirical formula might suggest. Actually, it was a tetramer (Figure 4) in which the Mg atoms have a coordination number greater than 4. 1 There is a caveat, however: the species t hat crystallizes from a Grignard reagent solution does not necessarily directly re? ect what species are swimming around in the solution. The crystalline solid shown in Figure 4 could well have self-assembled during the crystallization process by combination of two molecules of the C2H5Mg2Cl3 dimer and not been present in solution at all. Even in the case of monomeric â€Å"RMgX†in THF solution, the Schlenk equilibrium will be operative and the strongly Lewis basic THF apparently prevents halide bridging between Mg atoms.Consequently, the (10) Toney, J. ; Stucky, G. D. Chem. Commun. 1967, 1168. (11) Toney, J. ; Stucky, G. D. J. Organomet. Chem. 1971, 28, 5. 1600 Organometallics, Vol. 28, No. 6, 2009 Scheme 1 Figure 4. Molecular structure of [C2H5Mg2Cl3(C4H8O)3]2, a tetrameric Grignard reagent. Modi? ed from Toney and Stucky (J. Organomet. Chem. 1971, 28, 15. (copyright 1971, with permission from Elsevier)). presence of monomeric RMgX, R2Mg, and MgX2, all solvated, would resu lt in the measurement of an association factor of 1, as Walker and Ashby observed.There are so many factors that bear on the question of the constitution of a given Grignard reagent in ethereal solutionsthe Lewis basicity and steric properties of the ether solvent, the electronegativity and size of the halogen atom in RMgX, the nature and steric properties of the organic substituent on the magnesium atom. These will affect the magnitude of the equilibrium constant of the Schlenk equilibrium and the extent of Mg-X-Mg bridging. For most applications in synthetic chemistry it will suf? ce to take the easy way outsto regard and to write the Grignard reagent as RMgX.There is another interesting and useful property of ethereal Grignard reagent solutions. The magnesium species are weak electrolytes in such solvents of low dielectric constant, and â€Å"RMgX†solutions conduct an electric current. 12 The electrolysis of solutions of organomagnesium halides was studied in some detail by Kondyrew at the State Research Institute in Leningrad13 and by Ward Evans and his students at Northwestern University. 14 During the electrolysis, magnesium species migrate both to the cathode and to the anode. Scheme 1 shows the simplest picture based on RMgX. Metallic magnesium is formed at the cathode. 12) The earliest report appears to be a 1912 French paper: Jolibois, P. Compt. rend. Hebd. Seances Acad. Sci. 1912, 155, 213. See also: Nelson, ? J. M. ; Evans, W. V. J. Am. Chem. Soc. 1917, 39, 82. (13) (a) Kondyrew, N. W. Ber. Dtsch. Chem. Ges. 1925, 58, 459. (b) Kondyrew, N. W. ; Manojew, D. P. Ber. Dtsch. Chem. Ges. 1925, 58, 464. (c) Kondyrew, N. W. Ber. Dtsch. Chem. Ges. 1928, 61, 208. (d) Kondyrew, N. W. ; Ssusi, A. K. Ber. Dtsch. Chem. Ges. 1929, 62, 1856. (14) The Evans group published many papers in J. Am. Chem. Soc. during the 1933-1942 period. See, for example: (a) Evans, W. V. ; Lee, F.H. J. Am. Chem. Soc. 1934, 56, 654. (b) Evans, W. V. ; Field, E. J. Am. Chem. Soc . 1936, 58, 720. (c) Evans, W. V. ; Braithwaite, D. J. Am. Chem. Soc. 1939, 61, 898. (d) Evans, W. V. ; Braithwaite, D. ; Field, E. J. Am. Chem. Soc. 1940, 62, 534. (e) Evans, W. V. ; Pearson, R. J. Am. Chem. Soc. 1942, 64, 2865. The alkyl radicals formed at the anode can undergo the usual alkyl radical processes of coupling (to R-R), disproportionation (to RH + R(-H)), or, if the anode is composed of a reactive metal such as zinc, aluminum, cadmium, or lead, they can attack the anode to form an organometallic compound.A graduate student of Evans, David G. Braithwaite, joined the Nalco Chemical Co. after he graduated and developed an electrolytic process for the commercialscale syntheses of tetramethyl- and tetraethyllead antiknock agents in which the respective alkyl Grignard reagents were electrolyzed in a mixed THF/diethylene glycol dimethyl ether solvent system using a lead anode and a steel cathode. 15 The reactions of the Grignard reagents with organic, organometallic, and ino rganic substrates and their applications are too numerous and varied to be covered here.Not only do they ? nd extensive use on a small to moderate scale in research laboratories but they also have been prepared and utilized on a large scale in diverse industrial processes. For the most part they react as nucleophilic reagents, as would be expected, on the basis of the polarity of the carbon-magnesium bond, C? –Mg? +. However, they also can undergo electron transfer reactions with appropriate electron-acceptor substrates. They are weak bases capable of deprotonating the stronger weak organic acids such as terminal acetylenes and cyclopentadiene.Their basicity can be enhanced (as can be the basicity of organolithium reagents) by the addition to RMgX solutions in ethers of additives such as hexamethylphosphoric triamide (HMPA) and N-methyl-2-pyrrolidinone (NMP) or alkali-metal alkoxides. All such information can be found in books devoted solely or in part to Grignard reagents. 1 6 Two special topics are of current interest and merit special mention. (1) The preparation of highly functionalized organomagnesium reagents by Paul Knochel and his co-workers at the University of Munich17 by means of halogen-magnesium exchange (e. . , eq 3). The availability of reagents such as 3-8 (which must be utilized at low temperature) has added a new and spectacular dimension to Grignard reagent chemistry. (2) The synthesis of ole? ns, styrenes, 1,3-dienes and biaryl derivatives by the crosscoupling of Grignard reagents with organic halides. The crosscoupling of Grignard reagents with vinylic halides was discovered by Morris Kharasch and Charles Fuchs at the University of Chicago Organometallics, Vol. 28, No. 6, 2009 1601 Table 2.Transition Metal Halide Catalyzed Homocoupling of Phenylmagnesium Iodidea metal halide FeCl2 CoBr2 NiBr2 RuCl3 RhCl3 PdCl2 OsCl3 IrCl3 a amt, mol 0. 01 0. 01 0. 03 0. 0036 0. 0036 0. 00566 0. 00275 0. 003 amt of C6H5MgI, mol 0. 03 0. 03 0. 095 0. 0 108 0. 013 0. 0163 0. 007 0. 01 yield of biphenyl, % 98 98 100 99 97. 5 98 53 28 Taken from: J. Am. Chem. Soc. 1939, 61, 957. in 1943 during the classic studies of Kharasch on the chemistry of Grignard reagents in the presence of transition-metal halides. 6b Kharasch and Fuchs found that arylmagnesium bromides in diethyl ether reacted readily with vinylic halides of type RCHdCHX and R2CdCHX (but not CH2dC(R)X) to give styrenes in 50-75% yield when the reactions were carried out in the presence of 5 mol % of CoCl2 (eq 4). 18It was reported that other metal halides (of iron, nickel, and chromium) also were effective catalysts of this cross-coupling reaction. Benzylmagnesium chloride also reacted in this manner with vinyl bromide to give PhCH2CHdCH2 in 75% yield.Alkylmagnesium halides such as cyclohexyl- and n-butylmagnesium bromide, on the other hand, gave only â€Å"small to negligible†yields of the expected coupling product. The ArMgBrderived biaryl usually was obtained as a byproduct in these reactions. Such homocoupling of arylmagnesium halides in the presence of a transition metal halide as well as copper and silver halides was a known reaction. It had been investigated in 1939 by Gilman and Lichtenwalter, who found that aryl Grignard reagents undergo homocoupling in the presence of ca. 0 mol % of various transition-metal halides in diethyl ether solution to give the respective biaryl in high yield in most cases (eq 5, Table 2). 19 The metal halide, in addition to being the needed catalyst precursor, also served as an oxidizing agent and, in some cases (CoBr2, NiCl2, RhCl3), formation of a black solid indicated complete reduction to the metal. not occur in the absence of the organic halide but in its presence was vigorously exothermic. The added organic halide was only partially consumed and did not show up in the biaryl product.When p-bromotoluene was added to a phenylmagnesium bromide/CoCl2 catalyst reaction mixture, only biphenyl was formed. A re markable reaction! smost likely a free radical process, as Kharasch suggested. The organic halide was believed to function as an oxidizing agent. This interesting, simple, and potentially useful cross-coupling reaction, as exempli? ed in eq 4, was not adopted by the synthetic organic community right away. After a long dormancy it was rediscovered some 30 years later by a number of groups in the USA, Japan, and France, all of whom apparently were not aware of the 1943 Kharasch/Fuchs JACS paper. 1 Transition-metal catalysts other than CoCl2 were used, but the concept and the basic reaction were the same. In 1971 Tamura and Kochi reported a thorough study of the cross-coupling of Grignard reagents with vinylic halides catalyzed by soluble iron species in concentrations of ca. 10-4 M in THF at 0-25  °C. 26,27 Various Fe(III) compounds could be used as Fe catalyst precursors; the best were Fe(III) -diketonates such as Fe(RC(O)CHC(O)R)3 (R ) Ph, CH3, t-Bu). These exothermic reactions we re not free radical processes. The reactions of cis- and trans-propenyl bromide proceeded with retention of geometric con? uration (eqs 6 and 7) and were not adversely affected by the presence of 0. 4 M styrene. A ArMgBr + RCHdCHX 9 ArCHdCHR + MgBrX 8 (X ) Cl, Br) CoCl2 5 mol % (4) 2ArMgX + MXn f Ar-Ar + MgX2 + MXn-2 (5) A novel catalytic process for such ArMgX to Ar-Ar coupling was discovered by Kharasch and Fields when ethereal solutions of an aryl Grignard reagent that contained a catalytic amount (3 mol %) of CoCl2 were heated at re? ux for 1 h and then treated with an equivalent amount of an organic halide (C6H5Br, C2H5Br, i-C3H7Cl). 20 The coupling reaction to give Ar-Ar did (15) (a) Bott, L.L. Hydrocarbon Process. Petrol. Re? ner 1965, 44, 115. (b) Guccione, E. Chem. Eng. 1965, (June 21), 102. See also Part 2 of the tetraethyllead essay: (c) Seyferth, D. Organometallics 2003, 22, 5154 (pages 5172-5174). (16) (a) Krause, E. ; von Grosse, A. Die Chemie der metall-organischen Ve rbindungen; Gebruder Borntrager: Berlin, 1937; pp 14-61, 110-114. ? ? (b) Kharasch, M. S. ; Reinmuth, O. Grignard Reactions of Nonmetallic Substances; Prentice Hall: New York, 1954. (c) Handbook of Grignard Reagents; Silverman, G. S. , Rakita, P. E. , Eds. ; Dekker: New York, 1996. d) Grignard Reagents-New DeVelopments; Richey, H. G. , Ed. ; Wiley: Chichester, New York, 2000. (e) The Chemistry of Organomagnesium Compounds; Rappaport, Z. , Marek, L. , Eds. ; Wiley-VCH: Weinheim, Germany, 2008. (17) Knochel, P. ; Dohle, W. ; Gommermann, N. ; Kneisel, F. F. ; Kopp, F. ; Korn, T. ; Sapountzis, J. ; Vu, V. A. Angew. Chem. , Int. Ed. 2003, 42, 4302 (review). (18) Kharasch, M. S. ; Fuchs, C. F. J. Am. Chem. Soc. 1943, 65, 504. (19) Gilman, H. ; Lichtenwalter, M. J. Am. Chem. Soc. 1939, 61, 957. and earlier (back to 1914) references cited therein. 20) Kharasch, M. S. ; Fields, E. K. J. Am. Chem. Soc. 1941, 63, 2316. mechanism involving an organoiron(I) intermediate, obtained by reduction of the Fe(III) precursor by the Grignard reagent, was suggested. The results of a few experiments carried out on a 30-40 mmol scale (Table 3) showed that such iron-catalyzed reactions would be useful in the synthesis of ole? ns, but a broader study to optimize them and to broaden the scope of their application was not undertaken. The coupling of vinylic Grignard reagents with alkyl halides is catalyzed also by Ag(I) salts. 8 Thus, cis-propenylmagnesium (21) Two later â€Å"historical notes†22,23 and two book chapters24,25 that dealt with the cross-coupling reactions of Grignard reagents with vinylic halides also did not cite the Kharasch/Fuchs paper. (22) Tamao, K. J. Organomet. Chem. 2002, 653, 27. (23) Murahashi, S. -I. J. Organomet. Chem. 2002, 653, 27. (24) Kochi, J. K. Organometallic Mechanisms and Catalysis; Academic Press: New York, 1978; Chapter 14, Sections III and IV. (25) Hou, S. ; Negishi, E. -i. In Handbook of Organopalladium Chemistry; Negishi, E. -i. , Ed. , Wile y: New York, 2002; Vol. 1,Chapter III. 2. 6, pp 335408.As a historical note, the following quotation from this reference (p 335) is of interest: â€Å"Although the reaction of Grignard reagents with organic halides was shown to be catalyzed by various late transition metal compounds (the Kharasch reaction) in the 1950s, it was not until the early 1970s that the applicability of this catalytic method was extended to the cross-coupling involving alkenyl and aryl halides catalyzed by Ag, Fe and other late transition metals. †(26) (a) Kochi, J. ; Tamura, M. J. Am. Chem. Soc. 1971, 93, 1487. (b) Tamura, M. ; Kochi, J. Synthesis, 1971, 303. (27) Full papers: (a) Neumann, S.M. ; Kochi, J. K. J. Org. Chem. 1975, 40, 599. (b) Smith, R. S. ; Kochi, J. K. J. Org. Chem. 1976, 41, 502. (c) Reviews: ref 24. (d) Kochi, J. K. J. Organomet. Chem. 2002, 653, 11 (historical note). (28) (a) Whitesides, G. M. ; Casey, C. P. J. Am. Chem. Soc. 1966, 88, 4541. (b) Tamura, M. ; Kochi, J. J. Am. Chem . Soc. 1971, 93, 1483. 1602 Organometallics, Vol. 28, No. 6, 2009 Table 3. Alkenylation of Grignard Reagents using FeCl3 as Precatalyst (in THF)a R MgBr (amt, mmol) n-C6H13MgBr (40) CH2dCH(CH2)4MgBr (36) n-C6H13MgBr (40) a 1 R2Br (amt, mmol) CH2dCHBr (204) CH2dCHBr (102) CH3CHdCHBr (355)FeCl3 (amt, mmol) 0. 05 0. 05 0. 10 reacn temp,  °C 0 25 25 product (yield, %) n-C6H13CHdCH2 (83) CH2dCH(CH2)4CHdCH2 (64) n-C6H13CHdCHCH3 (67) (53/47 cis/trans mixture) Taken from: Synthesis 1971, 6, 303. Scheme 2 bromide reacted with methyl bromide in THF in the presence of an Ag(I) catalyst to give cis-butene-2, but a similar reaction of trans-propenylmagnesium bromide gave a 7:3 mixture of cisand trans-butene-2, respectively. 28b Apparently propenyl radicals were involved. A similar Grignard reagent based cross-coupling, ole? n synthesis in which a copper(I) catalyst was used was published by French workers. 9 Normant et al. reported that their reactions (e. g. , n-Bu(Et)CdCHI + i-PrMgCl in THF at -20  °C with a Cu(I) catalyst) proceeded with retention of con? guration. 29a For a reaction of CH3CHdC(CH3)MgCl with n-C3H7I in THF at 0  °C using CuI as catalyst, Linstrumelle reported that the coupling product obtained in 97% yield was 88% cis and 12% trans, while a similar reaction of CH2dC(CH3)MgBr with trans-n-C6H13CHdCHI gave a 4:1 trans/cis product. 29b TheuseofNi(II)catalystprecursorsforGrignardreagent-vinylic halide cross-coupling was reported in 1972 by Corriu and Masse30 and by Tamao, Sumitani, and Kumada. 1 The French group found Ni(II) acetylacetonate to be the most effective catalyst precursor, while the Japanese group favored a bis(tertiary phosphine)NiCl2 catalyst precursor and, especially, chelating diphosphine complexes such as (Ph2PCH2CH2PPh2)NiCl2. Reactions carried out in diethyl ether at re? ux generally gave excellent yields. This procedure has been carried out commercially on an industrial scale in the preparation of p-chloroand p-tert-butylstyrene. 3 2 Finally, the last to be discovered at that time and the most versatile procedure for the cross-coupling of Grignard reagents (29) (a) Normant, J. F. Commercon, A. ; Cahiez, G. ; Villieras, J. Compt. ? rend. Hebd. Seances Acad. Sci. , Ser. C 1974, 278, 967. (b) Derguini? Boumechal, F. ; Linstrumelle, G. Tetrahedron Lett. 1976, 3225. (30) Corriu, R. J. P. ; Masse, J. P. J. Chem. Soc. , Chem. Commun. 1972, 144. (31) (a) Tamao, K. ; Sumitani, K. ; Kumada, M. J. Am. Chem. Soc. 1972, 94, 1375. (b) See also ref 22. Later work: (c) Tamao, K. ; Kiso, Y. ; Sumitani, K. ; Kumada, M. J. Am. Chem. Soc. 1972, 94, 9268. (d) Kiso, Y. ; Tamao, K. ; Kumada, M. J. Organomet. Chem. 1973, 50, C12. (e) Kiso, Y. ; Tamao, K. ; Miyake, N. ; Yamamoto, K. ; Kumada, M. Tetrahedron Lett. 974, (No. 1), 3. (f) Tamao, K. ; Sumitani, K. ; Kiso, Y. ; Zembayashi, M. ; Fujioka, A. ; Kodama, S. ; Nakajima, I. ; Minato, A. ; Kumada, M. Bull. Chem. Soc. Jpn. 1976, 49, 1958. (g) Tamao, K. ; Kodama, S. ; Nakajima, I. ; K umada, M. ; Minato, A. ; Suzuki, K. Tetrahedron 1982, 38, 3347. (32) Banno, T. ; Hayakawa; Umeno, M. J. Organomet. Chem. 2002, 653, 288. (33) (a) Yamamura, M. ; Moritani, I. ; Murahashi, S. -I. J. Organomet. Chem. 1975, 91, C39. Full paper: (b) Murahashi, S. -I. ; Yamamura, M. ; Yanagisawa, K. -i. ; Mita, N. ; Kondo, K. J. Org. Chem. 1979, 44, 2408. (c) Historical note: ref 23. ith vinylic and aryl halides, that catalyzed by palladium complexes, was reported by Shun-Ichi Murahashi and coworkers in 1975. 33a The reactions were carried out in diethyl ether/benzene at room temperature using (Ph3P)4Pd as the catalyst precursor, and they proceeded stereospeci? cally in excellent yield (Scheme 2). Dang and Linstrumelle also used this procedure to prepare 1,3-dienes stereospeci? cally by the reaction of vinylic iodides with vinylic Grignard reagents. 34 Palladium-catalyzed cross-coupling of Grignard reagents with organic halides has been a very active area in organic synthesis.Reference 25 reviews (up to 2002) its application in (alkenyl) MgX-ArX, ArMgX-(alkenyl)X, and (alkenyl)MgX-(alkenyl)X coupling processes. A further chapter in this book deals with ArMgX-Ar? X coupling. 35 Another surge of research activity on cross-coupling of Grignard reagents with organic halides started around the turn of the century and still appears to be in progress at the present time (January 2009). Interest has revived in the use of iron complexes as precatalysts for the cross- and homocoupling of Grignard reagents,36 since iron complexes are cheaper than those of palladium and are nontoxic.The iron-catalyzed cross-coupling of organomagnesium bromides with vinylic bromides, although it produced ole? ns in good yield, was of interest to Jay Kochi, as noted above, primarily from the point of view of its reaction mechanism rather than of its potential for application in organic synthesis. After some 25 years several research groups carried out much experimental work which has shown iron-c atalyzed cross-coupling and homocoupling of Grignard reagents to be broadly applicable and very useful additions to the methods of organic synthesis.In 1995 Gerard Cahiez, at the Universite Pierre et Marie Curie ? ? in Paris, during the course of his extensive investigations of organomanganese chemistry, found that the cross-coupling of vinylic bromides with alkyl, vinylic, and phenylmanganese chlorides could be effected in good yield in the presence of 3 mol % of iron(III) acetylacetonate in a THF/N-methyl-2pyrrolidinone (NMP) mixed solvent at room temperature. 37 In a thorough study, this reaction was extended to the crosscoupling of vinylic halides with alkylmagnesium halides using 1 mol % of Fe(acac)3 and the same solvent mixture. 8 High yields of ole? nic products were obtained. Successful crosscoupling of Grignard reagents with AcO(CH2)6CHdCHCl, CH3C(O)(CH2)3CHdCHCl, Cl(CH2)4CBrdCH2, 9, and 10 are noteworthy as examples of the selectivity and functional group tolerance of this reaction. The scope of this chemistry was extended further when some of Knochel’s functionally substituted aryl Grignard reagents17 (vide supra) were reacted with vinylic bromides and iodides. 39 The cross-coupling reaction between aryl Grignard reagents and vinylic bromides and iodides also was found by Cahiez and co-workers to give ole? ic products in good yield with Organometallics, Vol. 28, No. 6, 2009 1603 Table 4. Iron-Catalyzed Biaryl Coupling Reactions a Table 5. Iron-Catalyzed Homocoupling of Grignard Reagents with Atmospheric Oxygen as Oxidanta a Taken from: J. Am. Chem. Soc. 2007, 129, 13788. palladium or nickel precatalysts. 42 Of these procedures, that of Cahiez et al. 41f appears to be the most useful. Alkyl halide/ alkylmagnesium halide cross-coupling is not a practical process. 43 RMgX + R? X 9 R-R? + MgX2 8 [Fe] (8)Iron-catalyzed reactions of aryl Grignard reagents with aryl halides to give biaryls generally are not synthetically useful. The desired cross-co upling products are obtained in only poor yield, the main product being the homocoupled biaryl derived from the aryl Grignard reagent (eq 9) (recall the Gilman/ Lichtenwalter and Kharasch/Fields reactions, vide supra). ArMgX + Ar? X f Ar-Ar? + (low yield) (major Ar-Ar product) (9) a Taken from: J. Am. Chem. Soc. 2007, 129, 9844. retention of geometric con? guration when carried out in THF solution in the presence of 10 mol % of MnCl2. 0 As noted above, Kharasch and Fuchs had found that attempts to cross-couple aryl Grignard reagents with alkyl halides in the presence of catalytic amounts of CoCl2 were unsuccessful. On the other hand, such reactions do occur in the presence of an iron precatalyst and various additives (eq 8, R? ) alkyl), as summarized in ref 36. A number of other groups have reported the results of their research directed toward development of an effective procedure for the process shown in eq 8, all using an iron precatalyst of one kind or another, various additives such as TMEDA, NMP, etc. nd generally diethyl ether (but sometimes THF) as solvent. 41 It is noteworthy that primary and secondary alkyl halides, i. e. , ones that contain hydrogen substituents on the carbon atom, can be cross-coupled with aryl Grignard reagents, a process that cannot be realized using (34) Dang, H. P. ; Linstrumelle, G. Tetrahedron Lett. 1978, 191. (35) Anastasia, L. ; Negishi, E. -i. Chapter II. 2. 5, pp 311-344, in ref 25. (To date palladium and nickel catalysts have been widely used to effect aryl-aryl cross-coupling reactions. However, arylmagnesium halides were found to undergo cross-coupling with aryl halides that contain electron-withdrawing activating substituents ortho or para with respect to the halogen substituent in the presence of 10 mol % of manganese(II) chloride (eq 10). 44 Cyclohexyl and 2-methylpropenyl Grignard reagents reacted with such substituted halobenzenes in a similar manner. Very (36) (a) Cahiez, G. ; Duplais, C. â€Å"Iron-Catalyzed Re actions of Grignard Reagents†, Chapter 13, pp 594-630 in ref 16e. (b) Furstner, A. ; Leitner, ? A. ; Mendez, M. ; Kraus, H. J. Am.Chem. Soc. 2002, 124, 13856 (a long ? paper that brings an excellent discussion of the literature, of questions concerning mechanism, and original results). (c) Sherry, B. D. ; Furstner, ? A. Acc. Chem. Res. 2008, 41, 1500. (37) Cahiez, G. ; Marquis, S. Tetrahedron Lett. 1996, 37, 1773. (38) Cahiez, G. ; Avedissian, H. Synthesis 1998, 1199. (39) Dohle, W. ; Kopp, F. ; Cahiez, G. ; Knochel, P. Synlett 2001, 1901. 1604 Organometallics, Vol. 28, No. 6, 2009 Table 6. Manganese-Catalyzed Homocoupling of Grignard Reagents with Atmospheric Oxygen as Oxidanta Scheme 4THF to a mixture of 3 mol % of FeF3  · 3H2O and 9 mol % of an N-heterocyclic carbene (SIPr  · HCl). In one example, chlorobenzene (1. 0 equiv) and p-CH3C6H4MgBr (1. 2 equiv) were added to this catalyst system and the reaction mixture was stirred at 60  °C for 1 day. The desired product, p -CH3C6H4-C6H5, was obtained in 98% yield. The homocoupling product, biphenyl, was present only in trace amount, while CH3C6H4C6H4CH3 was formed in 3% yield. Some examples of the application of this remarkable reaction are shown in Table 4. Good results were obtained only with aryl chlorides.Aryl bromides and iodides gave low biaryl yields. A German group reported similar MnCl2-catalyzed cross-coupling between various heterocyclic chlorides and aryl as well as alkyl Grignard reagents: e. g. , eq 11. 46 a Taken from: J. Am. Chem. Soc. 2007, 129, 13788. The homocoupling reaction of aryl Grignard reagents, mentioned earlier, also has received renewed attention recently, and synthetically useful procedures have resulted. Nagano and Hayashi developed a procedure in which the reaction is carried out in re? uxing diethyl ether in the presence of 1-5 mol % of FeCl3, NMP and 1. molar equiv of 1,2-dichloroethane (which serves as the oxidant). 47 Cahiez and co-workers have improved this procedu re by using THF as solvent, in which arylmagnesium halides, including the chlorides, are more easily prepared. 48 This procedure works well with Knochel’s functional arylmagnesium halides (Scheme 3). Of interest also is the clever construction of the tricyclic system 11 by intramolecular homocoupling (Scheme 4). (40) (a) Cahiez, G. ; Gager, O. ; Lecomte, F. Org. Lett. 2008, 10, 5255. (b) Alami, M. ; Ramiandrasoa, P. ; Cahiez, G. Synlett 1998, 325. 41) A selection: (a) Martin, R. ; Furstner, A. Angew. Chem. , Int. Ed. ? 2004, 43, 3955 (see also ref 36b and references cited therein). (b) Nagano, T. ; Hayashi, T. Org. Lett. 2004, 6, 1297. (c) Bedford, R. B. ; Bruce, D. W. ; Frost, R. M. ; Goodby, J. W. ; Hird, M. Chem. Commun. 2004, 2822. (d) Nakamura, N. ; Matsuo, K. ; Ito, S. ; Nakamura, E. J. Am. Chem. Soc. 2004, 126, 3686. (e) Bedford, R. B. ; Bruce, D. W. ; Frost, R. M. ; Hird, M. Chem. Commun. 2005, 4161. (f) Cahiez, G. ; Habiak, V. ; Duplais, C. ; Moyeux, A. Angew. Chem. , Int. Ed. 2007, 46, 4364. g) Cahiez, G. ; Duplais, C. ; Moyeux, A. Org. Lett. 2007, 9, 3253. (h) Guerinot, A. ; Reymond, S. ; Cossy, J. Angew. ? Chem. , Int. Ed. 2007, 46, 6521. (42) However, Terao and Kambe have recently developed new Pd- and Ni-based precatalyst systems which avoid the problem of -elimination of primary and secondary alkyl groups: Terao, J. ; Kambe, M. Acc. Chem. Res. 2008, 41, 1545. (43) (a) Tamura, M. ; Kochi, J. J. Organomet. Chem. 1971, 31, 289. (b) Rollick, K. L. ; Nugent, W. A. ; Kochi, J. K. J. Organomet. Chem. 1982, 225, 279. (44) Cahiez, G. ; Lepifre, F. Ramiandrasoa, P. Synthesis 1999, 2138. (45) Hatakeyama, T. ; Nakamura, M. J. Am. Chem. Soc. 2007, 129, 9844. (46) Rueping, M. ; Ieawsuwan, W. Synlett 2007, 247. (47) Nagano, T. ; Hiyama, T. Org. Lett. 2005, 7, 491. (48) Cahiez, G. ; Chaboche, C. ; Mahuteau-Betzer, F. Org. Lett. 2005, 7, 1943. Scheme 3 special, but generally applicable, reaction conditions developed by Japanese workers45 have ? nally prov ided the possibility of clean aryl-aryl cross-coupling reactions in which competitive homocoupling of the aryl Grignard reagent has been almost completely suppressed.In this procedure an active catalyst system was prepared by addition of 18 mol % of C2H5MgBr in Organometallics, Vol. 28, No. 6, 2009 1605 A further improvement resulted when it was found that atmospheric oxygen could replace the 1,2-dihaloethane as oxidant in the homocoupling of aryl, vinylic, and alkynyl Grignard reagents using either Fe or Mn catalyst precursors. 49 As Tables 5 and 6 show, this procedure gave excellent results. The most recent contribution to iron-catalyzed cross-coupling, which appeared during the preparation of the ? al draft of this paper, involves application of the old one-pot Barbier procedure in which FeCl3 served as precatalyst and stoichiometric amounts of magnesium turnings and TMEDA additive were used. A mixture of an alkyl and an aryl bromide was added to the mixture of precatalyst, TMEDA , magnesium, and solvent at 0  °C. Good yields of cross-coupled products were obtained. 50 There has been a great deal of activity in the areas of Grignard reagent/organic halide cross-coupling and aryl Grignard reagent homocoupling, and the coverage in this essay, whose focus is on the historical aspects, is far from exhaustive.Attention is called to the 2005 review by Frisch and Beller51 and especially (49) Cahiez, G. ; Moyeux, A. ; Buendia, J. ; Duplais, C. J. Am. Chem. Soc. 2007, 129, 13789. (50) Czaplik, W. M. ; Mayer, M. ; von Wangelin, A. J. Angew. Chem. , Int. Ed. 2009, 48, 607. (51) Frisch, A. C. ; Beller, M. Angew. Chem. , Int. Ed. 2005, 44, 674. to the recent Accounts of Chemical Research special issue on cross-coupling. 52 Since ? st reported in 1943, the cross-coupling of Grignard reagents with organic halides, thanks to further development by many later workers, has become a broadly applicable, very useful reaction in organic synthesis. There is much more about Grign ard reagents that I have not covered: the various procedures used in their preparation, the mechanism of their formation (which is still controversial), the more complex organomagnesium compounds such as bis(cyclopentadienyl)magnesium, magnesium butadiene, and magnesium anthracene, and the many kinds of reactions that Grignard reagents have been reported to undergo.But this is only a short essay, and so I have been able to cover only a few selected topics, ones which I hope will be of interest to the reader. More information can be found in the books that I have cited earlier. 16 Acknowledgment. My thanks, as always, to Professor Arnold L. Rheingold for the cover ? gure. OM900088Z (52) Acc. Chem. Res. 2008, 41, No. 11, 1439-1564, special issue. A collection of 11 reviews, many of them relevant to the subject matter of the present essay, with useful, up-to-date references.
Sunday, November 10, 2019
Functional Skills †Literacy Letter Writing Essay
I belong to a group called ‘Community Concern’. We as a group provide volunteers for community projects. I have recently seen the advert in the local paper about the old bus station being redeveloped and our group have all decided that we would like to volunteer to clean up the area before the work starts We have a lot of our own equipment, and we do supply things for this such as; Gardening equipment; †¢ Shovels †¢ Lawn movers †¢ Chainsaws †¢ Rakes †¢ Garden Forks †¢ Hedge trimmers and †¢ Leaf blowers General equipment; †¢ Buckets †¢ Yard brushes †¢ Paint †¢ Litter Pickers †¢ Gloves However, although we do provide this equipment there is on vital thing that we may need from the local council and that is a skip to put all the waste materials into once we’re done with it. I feel that this would be something we could discuss at a later time. Our group Community Concern are committed to improving the appearance of the local area and we feel that this project will strengthen the community and maybe even bring new people into the local area. Our Volunteers take pride in the work that they complete and are an asset to the group. They have completed a number of renovation projects over the years, the most recent being the re-decoration of the leisure centre a few weeks ago. I would like to thank you from all of us at Community Concern for taking the time to read this letter. And will leave you with our contact number in the hope that it would be possible to set up a meeting to discuss all the issues I have brought up today and hopefully to finalise some details and start planning the work!
Thursday, November 7, 2019
Black out essays
Black out essays There is a problem in the world today with crime. The children in our society are being taught that its the easy way to make money and get away with it. There are too many people getting robbed, mugged, raped, and even killed every second of everyday. The bad guys are getting away with committing crimes so they keep on doing bad things to good people, which leaves the problem of the victims, like me, to deal with the aftermath of putting our lives back together. It is frustrating to be victimized by these people that think its ok to rob and steal for a living or just for fun. The lack of attention from the authorities does not make it any easier to get on with our lives. To try and get some information, like are there any suspects, did you get any leads, do you think they will be back, what should I do if they do, are some of many that they cant seem to answer. But it seems that they are to busy with the next case and you (I) get put on the back burner and the bad guys get away agai n. A kind word would even be a nice thing to hear from them, but you dont get even that, all you get is youre just another victim of a crime, well, I knew that! I had gone to work on August 25, 2004 at 9:30 am after having breakfast with my friend Jerry Nyren as I do everyday to work at his pawn shop that he owns. I was in the back putting away some items that had forfeited and I heard the front door open at about 10:15am and two black males approximately 30 years old in age entered the store. They had come in and started asking Jerry questions about some jewelry, and I was call to show them a computer, but by the time I got to them they were not interested any more this puzzled me, but I could not tell Jerry anything while they were still in the store. At this time I had a sinking feeling in my stomach. They left, telling Jerry they needed to go to the ATM for some more money and that they would be back. They return...
Tuesday, November 5, 2019
Ubaidian Culture and the Roots of Mesopotamia
Ubaidian Culture and the Roots of Mesopotamia The Ubaid (pronounced ooh-bayed), sometimes spelled Ubaid and referred to as Ubaidian to keep it separate from the type site of el Ubaid, refers to a time period and a material culture exhibited in Mesopotamia and adjacent areas which predate the rise of the great urban cities. The Ubaid material culture, including ceramic decorative styles, artifact types and architectural forms, existed between about 7300-6100 years ago, over the vast Near Eastern region between the Mediterranean to the Straits of Hormuz, including parts of Anatolia and perhaps the Caucasus mountains. The geographic spread of Ubaid or Ubaid-like pottery, a pottery style which has black geometric lines drawn on a buff-colored body, has led some researchers (Carter and others) to suggest that a more accurate term might be Near Eastern Chalcolithic black-on-buff horizon rather than Ubaid, which implies that the core area for the culture was southern Mesopotamia- el Ubaid is in southern Iran. Thank goodness, so far theyre holding off on that. Phases While there is widespread acceptance of the chronological terminology for Ubaid ceramics, as you might expect, dates are not absolute across the entire region. In southern Mesopotamia, the six periods span between 6500-3800 BC; but in other regions, Ubaid only lasted between ~5300 and 4300 BC. Ubaid 5, Terminal Ubaid begins ~4200 BCUbaid 4, once known as Late Ubaid ~5200Ubaid 3 Tell al-Ubaid style and period) ~5300Ubaid 2 Hajji Muhammad style and period) ~5500Ubaid 1, Eridu style and period, ~5750 BCUbaid 0, Ouelli period ~6500 BC Redefining the Ubaid "Core" Scholars are hesitant today to re-define the core area from which the idea of Ubaid culture spread out because the regional variation is so extensive. Instead, at a workshop at the University in Durham in 2006, scholars proposed that the cultural similarities seen across the region developed from a vast inter-regional melting pot of influences (see Carter and Philip 2010 and other articles in the volume). Movement of the material culture is believed to have spread throughout the region primarily by peaceable trade, and various local appropriations of a shared social identity and ceremonial ideology. While most scholars still suggest a Southern Mesopotamian origin for black-on-buff ceramics, evidence at Turkish sites such as Domuztepe and Kenan Tepe is beginning to erode that view. Artifacts The Ubaid is defined by a relatively small set of characteristics, with a significant degree of regional variation, due in part to differing social and environmental configurations across the region. Typical Ubaid pottery is a high-fired buff body painted in black, the decorations of which become simpler over time. Shapes include deep bowls and basins, shallow bowls and globular jars. Architectural forms include a freestanding tripartite house with a T-shaped or cruciform central hall. Public buildings have a similar construction and a similar size, but have external facades with niches and buttresses. The corners are oriented to the four cardinal directions and sometimes are built top platforms. Other artifacts include clay disks with flanges (which might be labrets or ear spools), bent clay nails which were apparently used to grind clay, Ophidian or cone-headed clay figurines with coffee-bean eyes, and clay sickles. Head-shaping, modification of childrens heads at or near birth, is a recently-identified trait; copper smelting at XVII at Tepe Gawra. Exchange goods include lapis lazuli, turquoise, and carnelian. Stamp seals are common at some sites such as Tepe Gawra and Degirmentepe in northern Mesopotamia and Kosak Shamai in northwest Syria, but not apparently in southern Mesopotamia. Shared Social Practices Some scholars argue that decorated open vessels in the black-on-buff ceramics represent evidence for feasting or at least the shared ritual consumption of food and drink. By Ubaid period 3/4, region-wide the styles became simpler from their earlier forms, which were highly decorated. That may signify a shift towards communal identity and solidarity, a thing also reflected in communal cemeteries. Ubaid Agriculture Little archaeobotanical evidence has been recovered from Ubaid period sites, except for samples recently reported from a burned tri-partite house at Kenan Tepe in Turkey, occupied between 6700-6400 BP, within the Ubaid 3/4 transition. The fire that destroyed the house resulted in the excellent preservation of nearly 70,000 specimens of charred plant material, including a reed basket full of well-preserved charred materials. Plants recovered from Kenan Tepe were dominated by emmer wheat (Triticum dicoccum) and two-rowed hulled barley (Hordeum vulgare v. distichum). Also recovered were smaller amounts of triticum wheat, flax (Linum usitassimum), lentil (Lens culinaris) and peas (Pisum sativum). Elites and Social Stratification In the 1990s, Ubaid was considered a fairly egalitarian society, and it is true that social ranking is not very apparent in any Ubaid site. Given the presence of elaborated pottery in the early period, and public architecture in the later, however, that doesnt seem very likely, and archaeologists have recognized subtle cues which appear to support the subdued presence of elites even from Ubaid 0, although its possible that elite roles might have been transitory early on. By Ubaid 2 and 3, there is clearly a shift in labor from decorated single pots to an emphasis on public architecture, such as buttressed temples, which would have benefited the entire community rather than a small group of elites. Scholars suggest that might have been a deliberate action to avoid ostentatious displays of wealth and power by elites and instead highlight community alliances. That suggests that power depended on alliance networks and control of local resources. In terms of settlement patterns, by Ubaid 2-3, southern Mesopotamia had a two-level hierarchy with a few large sites of 10 hectares or larger, including Eridu, Ur, and Uqair, surrounded by smaller, possibly subordinate villages. Ubaid Cemetery at Ur In 2012, scientists at the Penn Museum in Philadelphia and the British Museum began joint work on a new project, to digitize C. Leonard Woolleys records at Ur. Members of the Ur of the Chaldees: A Virtual Vision of Woolleys Excavations project recently rediscovered skeletal material from Urs Ubaid levels, which had been lost from the record database. The skeletal material, found in an unmarked box within Penns collections, represented an adult male, one of 48 interments found buried in what Woolley called the flood layer, a silt layer some 40 feet deep within Tell al-Muqayyar. After excavating the Royal Cemetery at Ur, Woolley sought the earliest levels of the tell by excavating an enormous trench. At the bottom of the trench, he discovered a thick layer of water-laid silt, in places as much as 10 feet thick. The Ubaid-period burials had been excavated into the silt, and beneath the cemetery was yet another cultural layer. Woolley determined that in its earliest days, Ur was located on an island in a marsh: the silt layer was the result of a great flood. The people buried in the cemetery had lived after that flood and were interred within the flood deposits. One possible historic precursor of the Biblical flood story is thought to be that of the Sumerian tale of Gilgamesh. In honor of that tradition, the research team named the newly rediscovered burial Utnapishtim, the name of the man who survived the great flood in the Gilgamesh version. Sources Beech M. 2002. Fishing in the Ubaid: a review of fish-bone assemblages from early prehistoric coastal settlements in the Arabian gulf. Journal of Oman Studies 8:25-40. Carter R. 2006. Boat Antiquity 80:52-63. remains and maritime trade in the Persian Gulf during the sixth and fifth mllennia BC. Carter RA, and Philip G. 2010. Deconstructing the Ubaid. In: Carter RA, and Philip G, editors. Beyond the Ubaid: Transformation and integration in the late prehistoric societies of the Middle East. Chicago: Oriental Institute. Connan J, Carter R, Crawford H, Tobey M, Charrià ©-Duhaut A, Jarvie D, Albrecht P, and Norman K. 2005. A comparative geochemical study of bituminous boat remains from H3, As-Sabiyah (Kuwait), and RJ-2, Ras al-Jinz (Oman). Arabian Archaeology and Epigraphy 16(1):21-66. Graham PJ, and Smith A. 2013. A day in the life of  Antiquity 87(336):405-417.an Ubaid household: archaeobotanical investigations at Kenan Tepe, south-eastern Turkey. Kennedy JR. 2012. Commensality and labor in terminal Ubaid northern Mesopotamia. Journal for Ancient Studies 2:125-156. Pollock S. 2010. Practices of daily life in fifth millennium BC Iran and Mesopotamia. In: Carter RA, and Philip G, editors. Beyond the Ubaid: transformation and integration in the late prehistoric societies of the Middle East. Chicago: Oriental Institute. p 93-112. Stein GJ. 2011. Tell Zeiden 2010. Oriental Institute Annual Report. p 122-139. Stein G. 2010. Local identities and interaction spheres: Modeling regional variation in the Ubaid horizon. In: Carter RA, and Philip G, editors. Beyond the Ubaid: transformation and integration in the late prehistoric societies of the Middle East. Chicago: Oriental Institute. p 23-44. Stein G. 1994. Economy, ritual, and power in Ubaid Mesopotamia. In: Stein G, and Rothman MS, editors. Chiefdoms and . Madison, WI: Prehistory Press.Early States in the Near East: The Organizational Dynamics of Complexity
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