in fig1 and 11 14 in table 2 each fraction was then bioassayed and shown to be similarly effective in repelling and deterring mosquitoes components with high molecular weight gt 250 daltons are advantageous in that they 1 dissipate slowly from treated surfaces 2 provide long lasting protection against mosquitoes and 3 convey little if any offensive smell the relative abundance of such components was enhanced by treating garlic oil under vacuum thus stripping away lower boiling components in gc ead analyses of the high boiling residue four components elicited responses from mosquito antennae they were identified as 4 5 9 10 tetrathiatrideca 1 12 diene 6 methyl 4 5 8 9 tetrathiadodeca 1 11 diene 2 2 3 dithia 5 hexenyl 3 4 dihydro 2 h thiopyran and 3 2 3 dithia 5 hexenyl 3 4 dihydro 2 h thiopyran block et al 1998 compounds 11 14 in table 2 and shown to have a strong repellent and deterrent effect in bioassays to determine the part of the molecule responsible for deterrence we synthesized compounds 15 24 table 2 synthesis of 8 allylsulfanyloctan 1 ol compound 24 in table 2 is described as an example of the preparation of new semiochemical repellents see fig2 1 8 octanediol a was purchased from alfa aesar and was converted in a 1 step synthesis to 8 bromo 1 octanol b 60 70 yield by continuous liquid liquid extraction with n heptane and 48 aqueous hydrobromic acid by maintaining the aqueous level at ambient temperature alcohol b was produced with gt 99 purity warming.