Acetic esterification with

Esterification Starch acetate - Esterification with acetic anhydride or vinyl acetate Acetylated distarch adipate - Esterification with acetic anhydride and adipic anhydride Starch sodium octenylsuccinate - Esterification by octenylsuccinic anhydride... 

Tetraethylene glycol may be used direcdy as a plasticizer or modified by esterification with fatty acids to produce plasticizers (qv). Tetraethylene glycol is used directly to plasticize separation membranes, such as siHcone mbber, poly(vinyl acetate), and ceUulose triacetate. Ceramic materials utilize tetraethylene glycol as plasticizing agents in resistant refractory plastics and molded ceramics. It is also employed to improve the physical properties of cyanoacrylate and polyacrylonitrile adhesives, and is chemically modified to form polyisocyanate, polymethacrylate, and to contain siHcone compounds used for adhesives. 

Esterification. Extensive commercial use is made of primary amyl acetate, a mixture of 1-pentyl acetate [28-63-7] and 2-metliylbutyl acetate [53496-15-4]. Esterifications with acetic acid are generally conducted in the Hquid phase in the presence of a strong acid catalyst such as sulfuric acid (34). Increased reaction rates are reported when esterifications are carried out in the presence of heteropoly acids supported on macroreticular cation-exchange resins (35) and 2eohte (36) catalysts in a heterogeneous process. Judging from the many patents issued in recent years, there appears to be considerable effort underway to find an appropriate soHd catalyst for a reactive distillation esterification process to avoid the product removal difficulties of the conventional process. 

Recovery of dilute acetic acid is achieved by esterification with methanol using a sulfonated resin (Dowex 50w) in a packed distillation column (54). Pure methyl acetate is obtained. This reaction is second order in acetic acid, 2ero order in methanol, and partially diffusion controlled. 

Other Esters. The esterification of acetic acid with various alcohols in the vapor phase has been studied using several catalysts precipitated on pumice (67). 

Because of the insolubility of cellulose it is not possible to carry out uniform esterification with the lower organic acids (acetic acid, propionic acid etc.) and in those cases where incompletely substituted derivatives are required a two-stage reaction is employed. This involves total esterification in a medium in... 

In a typical process for manufacture on a commercial scale bleached wood pulp or cotton linters are pretreated for 12 hours with 40-50% sulphuric acid and then, after drying, with acetic acid. Esterification of the treated cellulose is then carried out using a mixture of butyric acid and acetic anhydride, with a trace of sulphuric acid as catalyst. Commercial products vary extensively in the acetate/ butyrate ratios employed. 

Enol esterification with acetyl chloride-acetic anhydride gives the A -trien-3-acetate, but reaction with isopropenyl acetate or with hot acetic anhydride-pyridine gives A " -trien-3-acetates. " Since A"" -3-ketones react with Girard reagents, these linear dienones can be separated from A ""-3-ketones. ... 

Normal Fischer esterification of tertiary alcohols is unsatisfactory because the acid catalyst required causes dehydration or rearrangement of the tertiary substrate. Moreover, reactions with acid chlorides or anhydrides are also of limited value for similar reasons. However, treatment of acetic anhydride with calcium carbide (or calcium hydride) followed by addition of the dry tertiary alcohol gives the desired acetate in good yield. 

Fipases and esterases are often used for Idnetic resolution of racemates, variously by hydrolysis, esterification, or transesterification of suitable precursors. Scheme 8.3-3 illustrates the principal for the resolution of a secondary alcohol by esterification with vinyl acetate. 

Example 5.4.2.1. Equilibrium in esterification of acetic acid with ethanol (after Smith and van Ness, 1988)... 

Benzyl chloride -i- sodium methoxide, and esterification of acetic acid with methanol SmithKline Beecham O Rourke (1993)... 

Substitution as a preceding reaction. In addition to the well known determination of primary and secondary alcohols via esterification with acetic anhydride in pyridine at about 98° C, esterification is possible at room temperature in ethyl acetate with perchloric acid117 or 2,4-dinitrobenzenesulphonic acid118 as a catalyst. However, as tertiary alcohols preferably split off their hydroxy group, they can be adequately determined by OH-substitution with HBr in glacial acetic acid according to... 

Helminen J, Leppamaki M, Paatero E and Minkkinen (1998) Monitoring the Kinetics of the Ion-exchange Resin Catalysed Esterification of Acetic Acid with Ethanol Using Near Infrared Spectroscopy with Partial Least Squares (PLS) Model, Chemometr Intell Lab Syst, 44 341. 

Example 6.6 Ethyl acetate can be produced by the esterification of acetic acid with ethanol in the presence of a catalyst such as sulfuric acid or an ion-exchange resin according to the reaction ... 

Notably, the Mukaiyama aldol/lactonizahon approach has been used in the total synthesis of panclicin D (2-258) [139b,c] and okinonellin B (2-261) (Scheme 2.61) [139d]. In the synthesis of 2-258, aldehyde 2-254 and the ketene acetal 2-255 were used to prepare the 3-lactone 2-256 with high simple and induced diastereoselectivity. There follows an esterification with the carboxylic acid 2-257. For the synthesis of 2-261, the aldehydes 2-259 and 2-252b were employed as substrates leading initially to the (1-lac tone 2-260. 

Chemat et al. have reported several microwave reactors, including systems that can be used in tandem with other techniques such as sonication [68], and ultraviolet radiation [69]. With the microwave-ultrasound reactor, the esterification of acetic acid with n-propanol was studied along with the pyrolysis of urea. Improved results were claimed compared with those from conventional and microwave heating [68]. The efficacy of the microwave-UV reactor was demonstrated through the rearrangement of 2-benzoyloxyacetophenone to l-(2-hydroxyphenyl)-3-phenylpropan-l,3-dione [69]. 

Later, in a more carefully controlled comparison, Pollington et al. [57] showed that the esterification of acetic acid with 1-propanol also occurred at the same rate under MW and conventional reflux. 

Scheme 10.2 Esterification of acetic acid with isopentyl alcohol.

Similar results were obtained in the esterification of acetic acid with 1-propanol performed in the presence of a heterogeneous silica catalyst [39]. The results showed that for this reaction microwave irradiation and conventional heating had similar effects on the reaction rate. 

Esterification of stearic acid and acetic acid with propanol and butanol in the presence of Fe2(S04)3/KSF montmorillonite [37]. The rate enhancement observed (1.5-2.5 times) was ascribed to the higher temperature of the catalyst bed (calculated to be 9-18 K above the bulk temperature). Reaction conditions batch (no stirring) and a stirred single-mode tank reactor, catalyst particle size 5 mm, 10-fold excess of alcohol. 

Esterification of acetic acid with 1-propanol in the presence of Si02 [39]. Reaction conditions reflux, tenfold molar excess of 1-propanol, batch reactor. 

Another important use of solubility parameters is in interpreting the effects of different solvents on the rates of reactions. In a chemical reaction, it is the concentration of the transition state that determines the rate of the reaction. Depending on the characteristics of the transition state, the solvent used can either facilitate or hinder its formation. For example, a transition state that is large and has little charge separation is hindered in its formation by using a solvent that has a high value of S. The volume of activation is usually positive for forming such a transition state which requires expansion of the solvent. A reaction of this type is the esterification of acetic anhydride with ethyl alcohol ... 

Transformations of Methyl 5-0-Benzyl-2-0-methyl-/3-I)-glueofuranosidurono-6,3-lae-tone (86) to Dimethyl (Z,E)-2-Methoxy-5-(phenylmethoxy)-2,4-hexadienedioatevl (87). ( Elimination employing DBU b oxidation with silver oxide-sodium hydroxide followed by diazomethane esterification c acidic glycoside cleavage, oxidation by dimethyl sulfoxide-acetic anhydride with formation of 5-0-benzyl-2-0-methyI-D-glucaro-1,4 6,3-dilactone, elimination by using DBU, followed by short treatment with diazomethane d elimination by DBU with subsequent diazomethane esterification e sodium borohydride in hexamethylphosphoric triamide 1 catalytic oxidation followed by short treatment with diazomethane " dimethyl sulfoxide-sulfur trioxide-pyridine-triethylamine.150)... 

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