Study On The Synthetic Process Of (E,E)-8,10-Dodecadien-1-ol

(E.E)-8,10-Dodecadien-l-ol is a key component of sex pheromone of Laspeyresia pomonella which has been used for monitoring,trapping,mating disruption as a feasible and believable pest management technique.Wittig reacion,reduction of alkynes,hydroboration of alkene and Grignard coupling of sorbic acid derivatives are the the most common methods for synthesis of(E,E)-8,10-dodecadien-l-ol.The main problems of the above synthetic methods were the low overall yields and poor stereoselectivities of long synthetic routes.Under the environment of reducing the amount of chemical pesticides.promoting green agriculture,producing safe foods,improving the synthetic yield and studying the process of(E,E)-8,10-dodecadien-l-ol is very urgent and necessary.Investigating the synthetic process of(E,E)-8,10-dodecadien-1-ol is very relastic and can be used as theoretical basis and technical guidance for the production in large scale.The synthetic processes were mainly investigated about the two methods to synthesize(E,E)-8,10-dodecadien-l-ol via Wittig reaction and coupling reaction of(E,E)-2,4-hexadienoic acid derivatives with Grignard regents.8-Bromo-l-octanol was synthesized through bromination from 1,8-octanediol as raw material with high selectivity,and then reacted with triphenylphosphine to give 8-hydroxy-alkylphosphonium bromide.(E,E)-8,10-Dodecadien-1-ol was obtained from the quaternary phosphonium salts and(E)-2-butene in strong alkaline condition.The chemical structure and geometrical structure of(E.E)-8,10-dodecadien-1-ol have been characterized by 1HNMR,13CNMR,IR,GC and GC-MS.GC analysis showed a purity of 98%,and the total yield was up to 42.5%based on 1,8-octanediol,which is larger than that of reference valued at 30%.This process examined the impact of bases,solvents,inorganic salts,reaction temperature,feeding modes,and other factors of th synthetic process were investigated based on the yield and the stereochemistry of the Wittig reaction.The process conditions of Wittig reaction through the reactive ylide was as follows:THF/hexane 1:1.5(v/v),reaction temperature:-70?,n-butyllithium as base with LiBr.And the feeding mode of n-butyl lithium was twice.Grignard coupling synthetic route to(E,E)-8,10-dodecadien-1-ol was synthesized with(E,E)-2,4-hexadienoic acid as starting material,followed by esterification,reduction with Red-Al,and acetylization.The key step of the coupling reaction of the Grignard reagent by using 6-chlorohexyl tetrabydropyranyl ether with(E,E)-2,4-Hexadienyl acetate was catalyzed by LI2CuCl4 to produce the target compound 10-dodecadien-1-ol in high geometrical selectivity.The chemical structure and geometrical structure of the product was identified by 1H NMR,13C NMR.IR?GC?GC-MS,and the structure information is all correct.The target compound(E,E)-8,10-dodecadien-1-ol was in 99%purity by GC analysis.The process conditions were got as follows:anhydrous THF as solvent,-10? as the reaction temperature.Another focuses of the article were the controlling of the geometrical isomer and the purification process.During the synthetic process of(E,E)-8,10-dodecadien-1-ol via Wittig reaction,the betaine intermediate could be created at first via adding n-butyllithium twice to the reaction system and then be combined with Li+to form the complex compound which led to the erythro isomer transform to the threo isomer,and then the·stereoselectivity of(E,E)-8,10-dodecadien-l-ol could be controlled as expected.In the synthetic process of coupling reaction of Grignard regents with(E,E)-2,4-Hexadienyl acetate,The trans conjugated double bonds was introduced to the(E,E)-8,10-dodecadien-1-ol through the synthesis process of coupling reaction using the(E,E)-2,4-hexadienoic acid as the starting material.The trans conjugated double bonds was retained and could not be broken in the reaction process that led to keep the regioselectivity of the target compound(E,E)-8,10-dodecadien-1-ol.The crude production is purified by molecular distillation in high vacuum and crystallization in ultralow temperature to gave(E,E)-8,10-dodecadien--ol with high stereoselectivity in 99.5%purity.And this is also an important innovation point of this article.