Synthesis of Urushiol Components and Analysis of Urushi Sap from Rhus vernicifera.

Abstract

An efficient method for synthesizing unsaturated urushiol components in urushi sap, was established, Wittig reaction of ylides derived from alkyl-and alkenyltriphenylphosphonium iodides, as side chain parts of urushiol, with 3-(8-oxo-1-octyl) catechol diacetate or 3-(10-oxo-1-decyl) catechol diacetate, as aromatic part of urushiol. Quantitative analysis of urushiol components in the urushi sap was done using GC for comparison with synthesized urushiol components as reference. In this manner, we proved the structures of most urushiol components and established percentage compositions of urushiols in the sap of Rhus vernicifera of Japan, Korea and China. (approximately 95%), by quantitative analysis of urushiol derived from Rhus vernicifera, the most abundant constituent was triene urushiol (approximately 71%) and the next abundant were mono (14-16%) and diene (5-8%) urushiol. Content was found to depend on growth conditions of the Rhus vernicifera tree and on the particular season for obtaining sap.