| Abstract: | Brassylic acid was partially esterified at 77°C. in toluene solution with ethyl, 2-methylpentyl, or nonyl alcohol and with p-toluenesulfonic acid used as catalyst. Half-esters were isolated from the respective reaction mixtures in yields of 28, 34, and 32% after reaction times of 2,6, and 8 hr. Both recovered brassylic acid and byproduct dialkyl ester were successfully used as starting materials in subsequent esterifications. Consequently, conversion of starting materials to half-ester would be increased in a process that involved continuous recycling of byproducts. Alkyl hydrogen brassylates were vinylated at 165°C. for 8 hr. with acetylene at 360 psig. The zinc salt generated in situ from zinc oxide served as catalyst and toluene as solvent. Yields were 80–88% and purities of products were 94–95%. Samples of 2-methylpentyl vinyl brassylate and nonyl vinyl brassylate of much higher purity were obtained by preparative gas–liquid chromatography or molecular distillation. Physical properties and experimental conditions for gas–liquid chromatographic analyses of both the alkyl hydrogen and alkyl vinyl brassylates are reported. |
