Tetrahedron published new progress about 594-81-0. 594-81-0 belongs to bromides-buliding-blocks, auxiliary class Bromide,Aliphatic hydrocarbon chain, name is 2,3-Dibromo-2,3-dimethylbutane, and the molecular formula is C8H11NO, Computed Properties of 594-81-0.
Skatteboel, L. published the artcileReactions of tertiary acetylenic halides with Grignard reagents. Preparation of cumulenes, Computed Properties of 594-81-0, the publication is Tetrahedron (1965), 21(6), 1357-67, database is CAplus.
Me2C(OH)CCCCMe (0.25 mole), 0.25 ml. CaCl2, and a small amount of hydroquinone in 104 ml. concentrated HCl mechanically shaken 3.5 hrs. yielded 90% Me2CClCCCCMe (I), b10 64-9°, n20D 1.5116. I (14.8 g.) in 15 ml. dry Et2O added dropwise in 1 hr. to 170 ml. MeMgBr (0.70M) with stirring at 20°, the mixture stirred 16 hrs. and refluxed 1 hr. with collection of evolved gases trapped at -78° over H2O, the mixture hydrolyzed with dilute aqueous HCl and the isolated product distilled gave 6.1 g. liquid, b12 50-2°, n26D 1.4998. The residue yielded 4.1 g. crystalline compound, purified by chromatography and recrystallization from MeOH to give [MeC CCCCMe2]2 (II), m. 140°. as chromatography of the liquid showed the presence of 64, 27, and 9% of 3 compounds (III, IV, V), separated by preparative gas chromatography. On the basis of analysis, spectroscopic data, and identity with a compound prepared by reduction of I with Zn in alc. III was shown to be Me2C:C:CHC CMe, b13 50°, n25D 1.5023. Repeated preparative gas chromatography gave a liquid, n25D 1.4792, recrystallized at low temperature from C5H12 to give IV, Me2CHCCCCMe, m. 27°. I (5 g.) in 30 ml. dry MeOH containing 1.5 g. Na kept 2 hrs. at 20° and refluxed 15 min., treated with H2O and extracted with C5H12 yielded 53% V, H2C:CMeCCCCMe, b13 53°, n25D 1.5402, extremely unstable except at low temperature under N. In one experiment the reaction mixture from the Grignard reaction was decomposed with D2O and the compounds separated Both II and V were unchanged but the product from III, ν 2225 cm.-1, N.M.R. lacking the band at 4.99 due to the allenic proton, was III-4-d. The new IV lacked the ir band at 1320 cm.-1 and it was evident that D was actually incorporated at the tertiary C atom of the Me2CH group. The gas evolved in the reaction analyzed by gas chromatography consisted of 99.9% C2H6 with traces of CH4. Use of EtMgBr gave 61% C2H6, 39% H2C:CH2, with traces of CH4. Although no cumulene was formed, the isolation of III showed that rearrangement had occurred and the reaction of Grignard reagents with tertiary acetylenic dihalides was studied. Me2CClCCCClMe2 (VI) (5.4 g.) in 15 ml. dry Et2O added dropwise in 30 min. to 50 ml. MeMgBr (1.54M) with stirring at 20° and the mixture stirred 1 hr., refluxed 1 hr., and hydrolyzed with dilute HCl (all operations under N) yielded 92% Me2C:C:C:CMe2 (VII), m. 40°. The gas evolved was 99.9% C2H6, but with EtMgBr consisted of 51:49 C2H6-H2C:CH2. VII was also produced by treatment of VI with Zn. VII was extremely sensitive to O with formation of a polymeric peroxide, isolated by extraction with hot CH2Cl2 to CHCl3 to give crystalline material, C8H12O2, m. 112-13° ozonized in CCl4 followed by treatment with Zn and H2O to give Me2CO. Me2CCl(C:C)2CClMe2 (VIII) (10.1 g.) in 15 ml. dry Et2O added dropwise in 1 hr. to 80 ml. MeMgBr (1.5M) with stirring at 20°, the mixture kept 1 hr. at 20° and decomposed with dilute HCl, the Et2O solution separated and dried gave ir spectrum, ν 2002 1625 cm.-1, and uv maximum 215, 228, 308, 321 mμ. Any attempt to isolate the cumulene gave highly unstable polymeric material, explosive at 70-80°, ν 1140 cm.-1, and containing considerably less O than the above peroxide. On the basis of the assembled data the cumulene structure, Me2C:C:C:C:C:CMe2 was assigned to the compound In the reaction of both VI and VIII dehalogenation had occurred and it was shown that the vicinal dihalide, Me2CBrCBrMe2 (IX) readily reacted with MeMgBr to yield Me2C:CMe2 (X) as the sole isolable product. Production of C2H6 from reactions with MeMgBr suggested that the dehalogenation reaction with IX to give the volatile X might be useful as a way of dimerizing Grignard reagent radicals. MeMgBr (140 ml., 1.4M) in Et2O added dropwise in 2 hrs. to 19.5 g. IX in 25 ml. dry Et2O and the mixture refluxed 1 hr., cooled, and hydrolyzed with dilute HCl and the washed and dried Et2O layer fractionated yielded 76% X, b. 70-2°, n20D 1.4101. The evolved gases contained 99.9% C2H6. Similar reaction of IX with EtMgBr gave X and evolved 52% C2H6, 48% H2C:CH2, and traces of CH4. Reaction of IX with PhMgBr gave only X and 71% Ph2, m. 69-70°. PhCCH (5.1 g.) in 20 ml. dry Et2O treated with 34 ml. 1.48M MeMgBr and the mixture refluxed 6 hrs., the mixture worked up as usual and the Et2O distilled under reduced pressure, the residue recrystallized from MeOH to yield 63% PhCCCPh, m. 87-8°, and the Et2O distillate analyzed by gas chromatography showed the presence of 62% X and PhCCH. Distillation of the distillate recovered 1.4 g. PhCCH. The formation of the allene and cumulenes was rationalized by a functional exchange-elimination mechanism involving radicals.
Tetrahedron published new progress about 594-81-0. 594-81-0 belongs to bromides-buliding-blocks, auxiliary class Bromide,Aliphatic hydrocarbon chain, name is 2,3-Dibromo-2,3-dimethylbutane, and the molecular formula is C8H11NO, Computed Properties of 594-81-0.
Referemce:
https://en.wikipedia.org/wiki/Bromide,
bromide – Wiktionary