Photochlorination of butyryl, valeryl and caproyl chloride

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AbstractThe photochlorination at room temperature of butyryl, valeryl and caproyl chloride in the liquid phase has been investigated.The acid chlorides were allowed to interact with a third of the equimolecular amount of chlorine under irradiation with a mercury lamp. The reaction mixtures obtained were separated by fractional distillation and counter current distribution according to Craig.The monochloro‐derivatives of the acid chlorides were characterized by preparing the ρ‐toluidides. The identity of α‐, β‐, δ‐ and ϵ‐chlorocaproic acids was established by synthesis.It is found that butyryl chloride yields <2% α‐, 50‐55% β‐ and 45‐50% γ‐chlorobutyryl chloride; valeryl chloride yields <1.5% α‐, 15‐20% β‐, 50‐55% γ‐ and 30‐35% δ‐chlorovaleryl chloride, while caproyl chloride produces < 1 % α‐, 5‐10% β‐, 25‐30% γ‐, 40‐45% δ‐and 20‐25% ϵ‐chlorocaproyl chloride.These results can be explained by reckoning with the fact that secondary hydrogen atoms are replaced more rapidly than primary and taking into account the deactivating effect of the carbonyl chloride group along the chain.