Study On The Catalytic Synthesis Of Acetals As Perfume

Acetals and ketals flavor as a new type of perfume receive more and more attention. The traditional synthetic methods usually use liquid acids such as sulfuric acid, p-toluenesulfonic acid and hydrochloric acid as catalyst, which have many disadvantages, including complicated technology, lower yield, badly corruption of equipments, and environment pollution. In order to solve the problems above, we synthesizes two new type of catalysts:the solid acids and ionic liquids.The main contents are as follows:1. The novel multi-SO3H functionalized strong Brφnsted acidic ionic liquid has been prepared by two typical procedures and its catalytic activities were investigated through the acetalization. Under mild and simple reaction conditions (at room temperature in air), using a small amount of the catalyst, aromatic aldehydes, aliphatic aldehydes, alkenyl aldehyde, and cyclic ketones all underwent successful transformation to the corresponding acetals in higher earning rate. The results clearly demonstrate that the novel catalyst is efficient, with almost quantitative conversion and exclusive selectivity for most reactions between carbonyl compounds and glycol. Different aldehydes(ketones) have a little difference in the reactivity because of the variance spatial structure. Benzaldehyde or aromatic aldehydes containing electron withdrawing substituent attached to the aromatic ring react very fast to furnish acetals due to the better electrophilicity at the carbonyl center compared to the aromatic aldehydes with electron donating substituent present in the aromatic nucleus, which may reduce the electophilicity at the carbonyl center by virtue of the conjugation. Also it can be deduced that the reactivity of glycol, mercaptoethanol and dithioethylene was different and the reactivity became higher with-SH increasing.2. Different solid acids have been prepared and their catalytic activities were investigated through the acetalization. HClO4/SiO2 as liquid acids on solid supports was prepared by impregnation method and its activities was investigated through the acetalization. The result indicates that using a small amount of the catalyst and reaction time 50 minutes, aldehydes and ketons have a high reactive activity. But this catalyst could not be recycled. So catalytic activity of resin (D072) as a second solid acid catalyst was investigated through the acetalization. Results showed that vavious aldehydes and ketons were converted to the corresponding acetals in higher earning rate. The experimental results also revealed that the catalyst could be recycled with high activity (with the yield over 97%). However, the amount of catalyst is too much. Finally, as a third solid acid catalyst, the catalytic activity of supported heteropolyacid on organic carbon catalyst was investigated through the acetalization. The catalyst is characterized by starting material cheap and easy to get and short procedure. Through the various carbonyl compounds used as substrates to react with glycol, 1,4-butanediol and 1,2-propylene glycol, their catalytic activities were investigated. The notable advantages of solid acids catalyst were (1) high recovery, (2)good selectivity, (3)less amounts of catalysts, (4)the catalyst can be used for more than eight times.