Study on Synthesis of Tonalide Musk and Karanal
|School||Henan University of Science and Technology|
|Keywords||Perfume Tonalide Musk Process Optimization Karanal Condensation Reaction Bouveault-blanc Reaction|
Synthetic perfume has been playing an significant role in the perfumery industry, owing to its unspecified season and location for production, as well as its advantage of stable quality, and low cost, et al. In this paper, the optimization of synthesis of Tonalide Musk was present in the first part, and then the synthetic route of Karanal was studied.In this thesis, a two-step synthesis of Tonalide Musk was investigated. Fristly, an intermediate of 1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (HMT) was synthesized from p-cymene and 2,3-dimethyl-1-butene in the presence of the tert-bytyl chloride as a supplier of electronic agent. The effect of different catalysts and solvents, as well as reaction time on the yield of HMT were investigated. The optimal conditions for inductrial production were as follows:hexamethylene was used as solvent; The molar ratio of raw materials is n(p-cymene): n(2,3-dimethyl-1-butene): n(tert-bytyl chloride): n(hexamethylene)= 2:1: 1.1: 3.5; AlCl3 was mixed with H2SO4 as catalyst on the ratio of n(AlCl3): n(H2SO4) = 10: 1, and the reation time was 60 min. The yield of HMT at the optimal condition was 86%.In the second step, Tonalide Musk (AHMT) was synthesized from HMT and acetyl chloride by Fridel-Crafts reaction. The total yield of AHMT was 80%. A high purity of 98% of Tonalide Musk (AHMT) was obtained by low temperature solvent crystallization of saturating ethanol solution to substitute the previously reported vacuum distillation and recrystallization operation. The product of HMT and AHMT were identified by1H-NMR,13C-NMR. This process effectively decreased prodction costs and provided the technical fundanmentals for large-scale production of Tonalide Musk.In the literatures, it was reported that the perfume Karanal can be synthesized by the condensation reaction of Ligustra and corresponding glycol. In this study, an aldol condensation reaction was applied to synthesize Karanal by backstepping design from Ligustra and 2-methyl-2-secbutyl-1,3-propanediol. Due to unavailability of 2-methyl-2-secbutyl-1,3-propanediol, it is synthesized by Bouveault-blanc reaction from ethanol sodium and 2-methyl-2-secbutyl diethyl malonate, which is obtained by the alkylation reaction from methyl diethyl malonate and 2-bromine butane. Thereby the synthesis of Karanal was made up of three steps.The first step of the synthesis of 2-methyl-2-secbutyl diethyl malonate was achieved. The yield of 75% was obtained at the molar ratio of raw materials as n(methyl diethyl malonate): n(2-bromine): n(ethanol sodium)= 1: 1.5: 3. The second step of the Bouveault-blanc reaction needs to be exploited further since its undetermined reaction mechanism and complicated side-reactions.