Wood protection properties of quaternary ammonium spiroborate esters derived from alkyl tartrates

Four new tetra-n-butylammonium spiroborates derived from dimethyl, diethyl, di-iso-propyl and di-n-butyl esters of L-tartaric acid have been prepared and their potential as environmentally benign wood protectants investigated. These compounds showed good activity in a no-choice cellulose paper bioassay with Coptotermes acinaciformis termites. The hydrolytic stability of these spiroborates is not high relative to other spiroborates, yet the tetra-n-butylammonium spiroborate derived from di-iso-propyl-L-tartrate showed remarkable permanence in timber in a demanding leaching test.