Selective mixed coupling of carboxylic acids (I). - Electrolysis, thermolysis and photolysis of unsymmetrical diacyl peroxides with acyclic and cyclic alkyl groups
作者:Michael Feldhues、Hans J. Schafer
DOI:10.1016/s0040-4020(01)97194-7
日期:1985.1
dodecanoyl octanoyl peroxide () affords the unsymmetrical coupling product octadecane()ins poor yield and selectivity. Thermolysis or photolysis in solution produces preferentially , but also considerable amounts of disproportionation products. At −78°C the neat peroxides are photolysed selectively to the mixed dimers. With straight chain and β-branched alkyl groups high yields are obtained (63 – 76 %)
14不对称的二酰基过氧化物(R 1 CO 2 -O 2 CR 2,R 1为十一烷基; R 2为例如甲基,丙基,戊基,壬基,2-甲基丙基,2-丙基,2-戊基,环丙基,环丁基,环己基)以85至92%的产率制备。十二烷酰基辛酰过氧化物()的方波电解会产生不对称的偶合产物十八烷(),收率和选择性都较差。溶液中的热解或光解优先产生,但也有相当数量的歧化产物。在-78°C下,纯净的过氧化物选择性地被光解成混合的二聚体。带有直链和β-支链烷基的高收率(63 – 76%),带有环烷基的中等收率(42 – 56%),而带有α-支链的二酰基过氧化物则中等收率(20 – 33%)。混合Kolbe电解与纯净过氧化物的低温光解的比较表明,在小规模转化方面,后一种方法在产率和选择性方面具有优势。