The invention provides an Illiberis ulmivora Graeser sex attractant, which comprises cis-7-dodecenoic acid-2-butyl ester and cis-9-tetradecenoic acid-2-butyl ester. The invention also provides a preparation method of the Illiberis ulmivora Graeser sex attractant, which comprises the steps of reducing
pimelic acid and
azelaic acid into 7-hydroxyheptanoic acid through
lithium aluminum hydride, brominating the 7-hydroxyheptanoic acid, performing acylating chlorination on the 7-hydroxyheptanoic acid and
thionyl chloride, esterifying the 7-hydroxyheptanoic acid and the
thionyl chloride with sec-butyl
alcohol to form 7-bromoheptanoic acid-2-
butanol ester and 9-bromononanoic acid-2-
butanol ester, preparing corresponding
phosphine salt from the 7-bromoheptanoic acid-2-
butanol ester and the 9-bromononanoic acid-2-butanol ester and
triphenylphosphine, and then carrying out
wittig reaction with n-valeraldehyde to synthesize a target compound. According to the Illiberis ulmivora Graeser sex attractant and the preparation method thereof, raw materials are easy to obtain, operation is easy and convenient, the cost is low, the product yield is high, the technological process is short, synthesis
reaction conditions are mild, no danger exists, the product is easy to separate, for the stereoisomerization problem, unstable
phosphorus ylide reacts with
fatty aldehyde, the product is mainly cis-olefin, the yield is 90% or above, the stable
phosphorus ylide reacts with
fatty aldehyde, and the product is mainly trans-olefin.