Mixtures of thionyl chloride and primary alcohols (and 2-propanol) can be used advantageously for the transformations of gamma-butyrolactone derivatives into the corresponding alkyl, allyl and propargyl 4-chlorobutyrates, for the methanolysis of an unstable gamma-butyrolactonol (gamma-hydroxy-gamma-butyrolactone) into the corresponding methyl 4-oxobutyrate dimethyl acetal and for the syntheses of alkyl, allyl and propargyl 4-chlorobutyl ethers from tetrahydrofuran.