Organic Lab Reactions 246

Organic Lab Reactions 246 - 6 H 5 C 6 H 4 C1 + C0 2 + C 6 H...

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DIRECT SUBSTITUTION IN BIPHENYL 241 Prom diazotized aniline and p-nitrosophenol Borsche 83 obtained 2-hy- droxy-5-nitrosobiphenyl (XXIII) in 8% yield, and with 2-methyl-4-ni- trosophenol he obtained 2-hydroxy-3-methyl-5-nitrosobiphenyl (XXIV). C 6 H 6 <^ \ C 6 H Decomposition of Aromatic Acyl Peroxides. The decomposition of aromatic acyl peroxides in liquid aromatic compounds is similar to the decomposition of nitrosoacetylarylamines and appears to involve the intermediate formation of free radicals. When dibenzoyl peroxide is heated in benzene, biphenyl, benzoic acid, and small amounts of phenyl benzoate, p-terphenyl, and quaterphenyl are produced. 34 That the sec- ond component enters into the reaction is shown by the formation of 4- chlorobiphenyl from the decomposition of di-p-chlorobenzoyl peroxide in benzene Si and of dibenzoyl peroxide in-chlorobenzene^ 3B ClC 6 H 4 C0-O—O-COC 6 H 4 C1 + C 6 H 6 -> C1C 6 H 4 —C 6 H 6 + CO 2 + C1C 6 H 4 COOH CH 6 CO • 0—0 • COCeUs + C 6 H 6 C1 -» C
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Unformatted text preview: 6 H 5 C 6 H 4 C1 + C0 2 + C 6 H 6 COOH Similar results have been obtained with other peroxides and benzene derivatives. A 29% yield of p-terphenyl can be obtained by careful de-composition of benzoyl peroxide in molten biphenyl at 95. 36 OTHER METHODS OF SYNTHESIS OF UNSYMMETRICAL BIARYLS Direct Substitution in Biphenyl. Direct nitration, chlorination, and bromination of biphenyl can.be used to prepare certain deriva-tives. 37 Direct nitration is probably the most satisfactory method of preparing large quantities of 2- and 4-nitrobiphenyl. In certain substi-tution reactions it is sometimes difficult to separate the mixture of 38 Borsche, Ann., 313, 211 (1900). 34 Gelissen and Hermans, Ber., 58, 285, 476, 984 (1925). 36 Hey, / . Chem. Soc., 1934, 1966. 'Gelissen and Hermans, Ber., 58, 764 (1925). 37 See Jenkins, McCullough, and Booth, Ind. Eng. Chem., 22, 31 (1930)....
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