| 摘要 |
Prepn. of 5-bromol-pentanal cpds. of formula (II) or their acetal dervis., comprises HBr being added to a 4-pentenal cpd. of formula (I) or its acetal deriv. in the presence of a radical initiator selected from diazo cpds. in a solvent. In the formulae, R1 and R2 each are H or 1-C alkyl. (I) include 2-ethyl-4-pentenal, 2,2-dimethyl-4-pentenal, 2-butyl-2-ethyl-4-pentenal, 2-butyl-4-pentenal, 1,1-dimethyl-2-ethyl-4-pentene, 1,1-diisopropoxy-2-ethyl -4-pentene, 2,2-dimethyl-4-pentenalethylene - acetal, 2-butyl-2-ethyl-4-pentenal -2,2-dimethyl-1,3-propylene-acetal, 2-ethyl-4-pentenal -1,3-propylene-acetal, 3,9-bis(1-ethyl-3-butenyl) -2,4,8,10- tetraoxaspiro(5.5) undecane. (II) include 5-bromo-2-ethylpentanal, 5-bromo-2,2-dimethylpentanal, 5-bromo-2-butyl-2 -ethylpentanal, 5-bromo-2-butylpentanal and their acetal derivs. Diazo cpds. include 2,2'-azobisisobutyroniti rle, 1,1-azobis(cyclohexane -1-carbonitrile), 2,2'-azobis(2,4-dimethyl-val eronitrile) and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). |
