| Carotenoids are a class of natural pigments with antioxidant activity .β-carotene is a kind of carotenoids, which is the most widely used with many functions. Large-scale synthesis ofβ-carotene has not been achieved in domestic production. Therefore, Studying the synthesis ofβ-carotene has an important significance. This paper mainly studied the synthesis ofβ-carote- ne, working out a synthetic route with simplified procedure and operation.The paper also studied the identification and stability comparison between syntheticβ-carotene and naturalβ-carotene obtained by purchase.This study synthesizedβ-carotene by six-step reactions with the main reaction of Wittig-Horner. Firstly, 2,7-dimethylocta-2,4,6-triene-1,8-dial, which is the intermediate of carotenoids, was synthesized. 2-butenyl-1,4-bisphosphonate was synthesized by the reaction between 1,4-dibromobut-2-ene and triethyl phosphate ,with the purity of 95% and the yield of 71.5% , and the optimum reaction temperature was 120℃and the optimum reaction time was 8 hours in this reaction.Then 2,7-dimethylocta-2,4,6-triene-1,8-tetramethyl acetal was synthesized by Wittig-Horner reaction between 2-butenyl-1,4-bisphosphonate and pyruvic aldehyde dimethyl acetal in alkaline conditions ,and the optimum extraction was petroleum ether - hexane (1:1) at the end of this reaction.Then 2,7-dimethylocta-2,4,6-triene-1,8-dial was synthesized by hydrolysis reaction in acidic conditions with the purity of 97% and the yield of 42.5% ,and the optimum reaction time was 5 hours in this reaction.Ethanediylbis tetraethyl phosphate ester was synthesized by the reaction between 1,2-dibromoethane and triethyl phosphate with the purity of 95% and the yield of 74.6% , and the optimum reaction temperature was 125℃and the optimum reaction time was 10 hours in this reaction.Then 3-Methyl-5-(2,6,6-trimehtyl-1-cycolhex-en-yl)-2,4-PentadienylPhosPhonates was synthesized by the Wittig-Horner reaction betweenβ-ionone and ethanediylbis tetraethyl phosphate ester in strong alkaline conditions,and the optimum base was potassium tert-butoxide and the optimum reaction temperature was 25℃in this reaction.At last,β-carotene ,the aim product,was synthesized by Wittig-Hornerreaction between 3-Methyl-5-(2,6,6-trimehtyl-1- cycolhex-en-yl)-2,4-PentadienylPhosPhonates and 2,7-dimethylocta-2,4,6-triene-1,8-dial with the purity of 96% and the yield of 81.58%( counted by 2,7-dimethylocta-2,4,6-triene-1,8-dial) and heating under reflux with Na was the optimum method to dry the solvent of THF .The synthetic products were confirmed by NMR, IR, UV, GC, GC-MS, LC, LC-MS in this study . syntheticβ-carotene was identified and compared the stability with naturalβ-carotene in this study.The study showed the differences between syntheticβ-carotene and naturalβ-carotene by comparing the spectrum of IR,UV,and LC,which provides a simple method to identify syntheticβ-carotene and naturalβ-carotene .This study also compared the stability of syntheticβ-carotene and naturalβ-carotene under the conditions of heating, lighting, and air oxidation, and the result showed that syntheticβ-carotene is more stable than naturalβ-carotene.It also showed that heating had the greatest impact in the three factors ,followed by lighting and air oxidation was the last one. This synthetic route is innovative and simpler than previous studies ,which can also be used as the synthetic route of some other carotenoids while changing some raw materials.Wittig-Horner reaction, which has been industrialized, was used 3 times in the synthesis.The instruments and equipments used in the synthesis are common and the raw materials are cheap ,which reduce the costs of the synthesis.Therefor,this paper supports a valuable reference in the synthesis research and industrialization of carotenoids in our country.
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