Esterification of phenols

A reaction which is related to hydroxy-de-diazoniations is the formation of aryl trifluoromethylsulfonic esters (aryl triflates, ArOSC CFs) which became widely used reagents because of their leaving-group properties. The classical method of synthesis by esterification of phenols with trifluoromethane-sulfonic anhydride or -sulfonyl halide is, however, not applicable for the preparation of aryl triflates bearing a (free)... 

It therefore appeared that a general mechanism for enzymatic esterification of phenolic acids with glucose was operative, whereas the reaction with other alcoholic moieties proceeded via carboxyl-activated acyl derivatives. [In this context it should be emphasized that glucose esters must not be confused with glucosides different enzymes are involved in the biosynthesis of these two types of phenolic glucose derivatives (36)]. 

Topakas, E., H. Stamatis, P. Biely, D. Kekos, B J. Macris, and P. Christakopoulos. 2003. Purification and characterization of a feruloyl esterase from Fusarium oxysporum catalyzing esterification of phenolic acids in ternary water-organic solvent mixtures. J. Biotechnol. 102 33-44. 

Methoxy carbony lotion. Aryl triflates or iodides are converted into alkyl benzoates by reaction with CO and an alcohol at 70° catalyzed by Pd(OAc)2 in combination with dppp yields are 72-95%. The method is useful for esterification of phenols under mild conditions.2... 

Esterification. DCC has been satisfactory only for esterification of phenols and thiophenols because of variable yields. However, if 4-dimethylaminopyridine (3, 118-119 5, 26) or 4-pyrrolidinopyridine (this volume) is added as catalyst, alcohols and thiols are csterified readily at rm temperature in satisfactory yields. Sterically... 

This reaction has wide application for the preparation of esters. The difficulties encountered in method 285 because of a reversible reaction are avoided. Esters of tertiary alcohols and phenols are best prepared in this way. The formation of tertiary halides from tertiary alcohols is prevented by carrying out the reaction in the presence of powdered magnesium or dimethylaniline which react with the hydrogen chloride as it is formed. The esterification of phenols is effected in the same manner. Magnesium or pyridine is added to combine with the hydrogen halide. Pyridine has replaced aqueous alkali formerly used for this purpose... 

Ester iealUm of phenols. The direct esterification of phenols is catalyzed by a combination of boric acid and sulfuric acid. Thus phenyl benzoate (I) can be prepared... 

Diazomethane is not ideal for esterification of phenolic acids because the phenolic hydroxyl groups are also methylated, albeit at a slower rate, which may lead to mixtures of partially methylated products. However, esterification can usually be achieved without O-methyl ether formation by cooling the reaction mixture to below 0°C [54,55]. 

The compounds were obtained by dii ect esterification of phenols by bis-sulphochloride using triethylamine as a base.The reaction x roceeds smoothly and give good yields. However, the use of chloroform in the naphtol series vjas necesse to dissolve the chloride. 

NaH has been recommended for the benzylation of carbohydrates Direct esterification of phenols occurs quite readily if the resulting water is removed by means of a Dean-Stark trap A simple preparation of ketenimines from amides and a convenient synthesis of azoxy compounds, including aromatic-aliphatic ones have been published. 

In addition, trifluoracetic anhydride has been a useful acid catalyst for the esterification of phenols. The use of heavy metal salts as effective esterification catalysts has been widely reported. For example, BuSnOjH and BujSnO are equal or superior to p-MeC6H4S03H as esterification catalysts and do not effect appreciable dehydration of secondary alcohols. It has been reported that catalytic activities generally descend in the order Sn, Co" , Fe" , Al, Bi, Cr, Sn", Cu, Co Pb, Fe+ Zn, Ni, Mn, Cd, Mg, Ba, K, and CIO4, SO4, PhSOj, Cl, Zr, I, NO3. The use of 1 wt% of Fe2(S04)3 is recommended as a noncorrosive catalyst in steel. 

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