Esterification and Etherification

Acetates of Morita-Baylis-Hillman (MBH) adduct 2 can be stereoselectively prepared by the reaction of acetyl chloride in the presence of a base or, alternatively, acetic anhydride in cone. H2S04. However, acetates 2 derived from aromatic aldehydes (R = Ar) prefer to undergo isomerization to generate the thermodynamically more stable acetate 3, either by intramolecular rearrangement 

The Chemistry of the Morita Baylis-Hillman Reaction By Min Shi, Fei-Jun Wang, Mei-Xin Zhao and Yin Wei Min Shi, Fei-Jun Wang, Mei-Xin Zhao and Yin Wei 2011 Published by the Royal Society of Chemistry, www.rsc.org 

Acetates 2 are reactive intermediates that can be used in iS n2 substitution reactions with C-, N-, 0-, S- and P-nucleophiles, leading to multi-substituted alkenes as advanced synthetic scaffolds (Section 3.8). 

More recently, Kumar and Swamy reported the transformation of the MBH adduct 22 - which is derived from fresh ferrocenecarboxaldehyde or aromatic 

The racemic imidates 35 and carbamates 36, which were obtained from an MBH adduct, can be transformed into enantioenriched amides 37 and amines 38 via the regio- and enantioselective [l,3]-sigmatropic O- to A-rearrangement directly or through a decarboxylation catalyzed by cinchona alkaloids. 

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Esterification and etherification may be catalyzed by mineral acids or BF3. The reaction of isobutylene with methanol to make MTBE is catalyzed by a sulfonated ion exchange resin. 

Abstract Polyfunctionality of carbohydrates and their low solubility in conventional organic solvents make rather complex their conversion to higher value added chemicals. Therefore, innovative processes are now strongly needed in order to increase the selectivity of these reactions. Here, we report an overview of the different heterogeneously-catalyzed processes described in the literature. In particular, hydrolysis, dehydration, oxidation, esterification, and etherification of carbohydrates are presented. We shall discuss the main structural parameters that need to be controlled and that permit the conversion of carbohydrates to bioproducts with good selectivity. The conversion of monosaccharides and disaccharides over solid catalysts, as well as recent advances in the heterogeneously-catalyzed conversion of cellulose, will be presented. 

Here we report an overview of the different heterogeneously-catalyzed pathways designed for the selective conversion of carbohydrates. On the basis of these results, we shall try to determine the key parameters allowing a better control of the reaction selectivity. Water being commonly used as solvent in carbohydrate chemistry, we will also discuss the stability of solid catalysts in the aqueous phase. In this review, heterogeneously-catalyzed hydrolysis, dehydration, oxidation, esterification, and etherification of monosaccharides and polysaccharides are reported. 

Benzyl alcohol readily undergoes the reactions characteristic of a primary alcohol, such as esterification and etherification, as well as halide formation. In addition, it undergoes ring substitution. In the presence of acid, polymerization is observed, and the alcohol can be thermally dehydrated to toluene [108-88-3], Catalytic oxidation over copper oxide yields benzaldehyde benzoic acid is obtained by oxidation with chromic acid or potassium permanganate. Catalytic hydrogenation of the ring gives cyclohexylmethanol [100-49-2]. 

Many reactions known in chemistry under special names, such as neutralization, esterification and etherification me dehydration reactions. See also Esterification. 

Functionalisation of the polymer backbone through reaction of the hydroxyl groups (esterification and etherification), nucleophilic displacement reactions, oxidation and selective reactions at the terminal reducing ends... 

Since cellulose is a polyhydroxyl alcohol, it can undergo esterification and etherification modifications. The properties of the derivatives depend heavily on the... 

Amorphous Sn-, Si-, and Al-containing mixed oxides with homogeneous elemental distribution, elemental domains, and well-characterized pore architecture, including micropores and mesopores, can be prepared under controlled conditions by use of two different sol-gel processes. Sn-Si mixed oxides with low Sn content are very active and selective mild acid catalysts which are useful for esterification and etherification reactions [121]. These materials have large surface areas, and their catalytic activity and selectivity are excellent. In the esterification reaction of pentaerythritol and stearic acid catalytic activity can be correlated with surface area and decreasing tin content. The trend of decreasing tin content points to the potential importance of isolated Sn centers as active sites. 

In addition to the esterification and etherification studies, the presence of three alcoholic hydroxyl groups has been shown by the action of metallic sodium in liquid ammonia on cellulosic materials. - For each D-glucose unit, one atom of sodium reacts readily while the two other atoms enter more slowly. 

Figure 1 shows the repeating glucose units of cellulose with the carbons labeled, including those with the reactive 2, 3, and 6 hydroxyls. Ihe most important reactions of cotton cellulose commercially are esterification and etherification, with the products of etherification ranking first. It is generally agreed today among textile scientists that durable press cellulosic textiles ow their smooth-drying and resilient properties to the reactivity of formaldehyde and its amide derivatives with cellulose to produce crosslinks between adjacent cellulose chains (Figure 2). Hovever, the theory that crosslinking was responsible for increased resiliency developed only after the treatmaits were in wide use.

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