Synthesis Of Odd-numbered Fatty Acids From Natural Even-numbered Fatty Acids

The fatty acids are the main derivatives of grease, and the biosynthesis products are mainly even-numbered fatty acids which is governed by the catalysis mechanism combined Malonyl-CoA and Acetyl-CoA. They can be used for the production of the stearic acid, soap, fatty acid methyl esters, fatty alcohols, fatty amines and other basic chemicals, and they are widely used in the fields of industrial productions, surfactant, the fine chemical and pharmaceutical industry. The odd-numbered fatty acids (OFA) were almost negligible in nature,which were occasionally prepared in small amounts by oxidation of olefin, or by fermentation route. A novel synthesis route of OFA is developed in this paper from natural fatty acids of one more carbon atom through chlorination, hydrolysis and followed by decarboxylation.Sodium a-hydroxyl dodecanoate (SHD) was simply synthesized directly from natural dodecanoic acid (DA) through a-chlorination reaction and hydrothermal alkaline hydrolysis, and structure of a-hydroxyl dodecanoic acid (HDA), the acidified product of SFID, was identified by FT-IR,1H NMR, and ESI-MS. The influence of reaction temperatures, reaction time and alkaline concentrations on the yield of SHD was investigated. The experimental results indicated that the yield of SHD was98.7%when alkaline hydrolysis was run under hydrothermal conditions in w(NaOH)=10%and5%more than the stoichiometry (n(NaOH): n(CDA)=2.1:1) at160℃for6h.Meanwhile, the yield of α-hydroxyl fatty acid (C14～C16) could reach97%at the same conditions.In this paper, the undecanoic acid (UA) could be synthesized from SHD through decarboxylation reaction at high-temperature and acidification reaction. The structure of UA was identified by FT-IR and1H NMR. The relative molecular weight was confirmed by ESI-MS. The results indicated that the yield of SU could reach to78.0%under the following conditions:using modified chromatography tank as heater with a reticular stirring rod at240℃for2.5h. Meanwhile, the yield of the sodium tridecanoate (ST) could reach70.6%at250℃for2.0h.Some surfactant properties of SHD, SU and ST such as Kraft point (KP), hard ion resistance, requirement of lime soap dispersant, foaming ability, surface tension and cmc were determined and compared with sodium dodecanoate (SD). It was showed that the KP of SUD was35℃and8℃lower than that of parent SD, which means SHD had better cold water solubility. The hard ion resistance of SHD was somewhat higher than that of SD and the requirement of lime soap dispersant of SHD decreased to one half of the SD which showed that SHD displayed better solubility in hard water than that of SD. Therefore, SHD showed the potential to act as the new soap-base material applied in cold water or hard water. The experimental results showed that the Krafft points of SU and ST were lower or even far lower than that of SD, which means the former had better solubility in cold water. This discovery shed light on formulations of soap-based detergents which were bothered longtime by poor low-temperature solubility of sodium soap derived from natural fatty acids.In addition, the study also revealed that SU had had good antibacterial activity, which may contribute further to shed light on the the development of sodium the odd-numbered fatty acid.