Synthesis of Glucose Bolaform Surfactant by Using Solventless Method

Of all the organic compounds in nature, carbohydrates are the most abundant. Among the carbohydrate components, glucose is finding increasing industrial applications because of the broad range of functional properties they exhibit. To widen their uses, glucose structures need to be modified so as to alter their physical and chemical properties to suit new uses. Therefore, the present study developed a technique to modify glucose by using a solventless method, using formic acid as ring initiator to produce glucose fatty acid esters. The major advantage of this process is that it does not require solvent and after purification is usable in food or pharmaceutical industries. Ionin liquid is green and non-toxic, but not applicable to the present study. It is due to ionic liquid cannot be purified by distillation and trace impurities can have significant impact on physical properties. A number of nonionic bolaform surfactants were prepared containing glucose, connected via hydroxyl groups in the sugar molecules, using acid dichloride as acylating agent and as a hydrophobic moiety for the surfactant molecule. A stream of nitrogen gas had been used to eliminate the hydrochloric acid produced by the reaction. The optimum conditions in esterification of methanedioate-bis-glucopyranoside, 1,4-buthanedioate-bis-glucopyranoside, 1,6-hexanedioate-bis-glucopyranoside and 1,7-heptanedioate-bis-glucopyranoside had been studied based on the highest percentage of the mass increased as compared to the initial glucose sample. About 71.06% of methanedioate-bis-glucopyranoside, 64.39% of 1,4-buthanedioate-bis-glucopyranoside, 57.73 of 1,6-hexanedioate-bis-glucopyranoside and 49.60% of 1,7-heptanedioate-bis-glucopyranoside were obtained under the optimum conditions. The optimum condition for the esterification is 45ºC and molar ratio of 2:1 of glucose to acid dichloride in the reaction time of 50 minutes. The result indicates that the short chain acid dichloride is easier to react with glucose to formed glucose bolaform ester than long chain acid dichloride. This is due to a more steric hindrance from longer fatty acid chain. This improved method allows of the invention allows for the preparation of saccharide fatty acid ester with less caramelization. The reduction of caramelization allows for the formation of products having better (lighter) colour characteristic. Compounds were characterized by spectroscopic technique, i.e: infrared (IR) and nuclear magnectic resonance spectroscopy (NMR). Esterification was evidenced by the presence of ester carbonyl peak in Fourier transform infrared (FT-IR). 1H NMR spectrum showed that there is a significant change in chemical shift for hydroxyl group in position 1. It is very obvious that only the primary hydroxyl groups at C1 of the glucose unit, being the most reactive site as a result of which single di-glucose ester product is obtained. Glucose bolaform surfactants of different chain length is being synthesized. The physical properties of these surfactants were determined and the effects of the different spacer/linker on surfactants properties were studied.

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