Acetyl Chloride esterification

The synthesis of 2,4-dihydroxyacetophenone [89-84-9] (21) by acylation reactions of resorcinol has been extensively studied. The reaction is performed using acetic anhydride (104), acetyl chloride (105), or acetic acid (106). The esterification of resorcinol by acetic anhydride followed by the isomerization of the diacetate intermediate has also been described in the presence of zinc chloride (107). Alkylation of resorcinol can be carried out using ethers (108), olefins (109), or alcohols (110). The catalysts which are generally used include sulfuric acid, phosphoric and polyphosphoric acids, acidic resins, or aluminum and iron derivatives. 2-Chlororesorcinol [6201-65-1] (22) is obtained by a sulfonation—chloration—desulfonation technique (111). 1,2,4-Trihydroxybenzene [533-73-3] (23) is obtained by hydroxylation of resorcinol using hydrogen peroxide (112) or peracids (113). 

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. ... 

As previously discussed, solvents that dissolve cellulose by derivatization may be employed for further functionahzation, e.g., esterification. Thus, cellulose has been dissolved in paraformaldehyde/DMSO and esterified, e.g., by acetic, butyric, and phthalic anhydride, as well as by unsaturated methacrylic and maleic anhydride, in the presence of pyridine, or an acetate catalyst. DS values from 0.2 to 2.0 were obtained, being higher, 2.5 for cellulose acetate. H and NMR spectroscopy have indicated that the hydroxyl group of the methy-lol chains are preferably esterified with the anhydrides. Treatment of celliflose with this solvent system, at 90 °C, with methylene diacetate or ethylene diacetate, in the presence of potassium acetate, led to cellulose acetate with a DS of 1.5. Interestingly, the reaction with acetyl chloride or activated acid is less convenient DMAc or DMF can be substituted for DMSO [215-219]. In another set of experiments, polymer with high o -celliflose content was esterified with trimethylacetic anhydride, 1,2,4-benzenetricarboylic anhydride, trimellitic anhydride, phthalic anhydride, and a pyridine catalyst. The esters were isolated after 8h of reaction at 80-100°C, or Ih at room temperature (trimellitic anhydride). These are versatile compounds with interesting elastomeric and thermoplastic properties, and can be cast as films and membranes [220]. 

Esterification of 104 with diazomethane gives 70 in quantitative yield.80 The low yield previously obtained29,31 may have been due to impure starting-material. Compound 70 is crystalline,29,31 and may be used for the preparation of the ketopyranosyl chloride 112 by the method that Kuhn and coworkers109 reported for the synthesis of the analogous halide of NeuAc. In this procedure, compound 70 is dissolved in acetyl chloride, and the solution is cooled to —70°, saturated with hydrogen chloride gas, and allowed to warm to room temperature in a sealed container. The preparation of 112 in this way was first reported by Bhattachaijee and coworkers,101 and, shortly thereafter, by Unger and coworkers.128 The Canadian authors synthesized the... 

Besides direct solid phase fixation, the functional OH-group of 49 may be used for further transformations. Esterification with acetyl chloride at the OH-linker (Scheme 27) leads to 50, providing a heteroscorpionate ligand with the protected OH-linker. An intramolecular hydrogen bridge is found in the X-ray structure [d(01-N21) = 2.478 (3) A] between the carboxylic acid and the pyrazole nitrogen (Fig. 32b). 

It has been demonstrated that organotin-mediated multiple carbohydrate esterifications can be controlled by the acytaring reagent and the solvent polarity. When acetyl chloride is used, the reactions are under thermodynamic control, whereas when acetic anhydride is employed, kinetic control takes place. Very good selectivity can furthermore be obtained in more polar solvents. These results can be used in the efficient preparation of prototype carbohydrate structures. 

Dihexylxylaramide (2). To a 250 mL round-bottom flask equipped with a magnetic stirrer was added methanol (150 mL), and the flask then cooled to 5 C. Acetyl chloride (5 mL) was added to the cold methanol and then xylaric acid (18 g, 0.18 mol, reference 18) was added to the methanolic HCl solution. The reaction mixture was refluxed for 16 h, concentrated to a syrup, and residual water removed from the syrup by azeotropic distillation with benzene. Esterification was complete but the product (1) contained more than one ester component as both ester and 5-membered lactone functions were observed in its IR spectrum (neat, 1745 and 1795 cm, ester and lactone C=0 respectively). 

The purpose of the first reaction with methanesulfonyl chloride (mesyl chloride) is to form a mesylate ester, a derivative with a better leaving group than hydroxide. Then, the Sn2 reaction can proceed more favourably. Esterification with mesyl chloride is mechanistically analogous to esterification with acetyl chloride. 

Finally, Lecomte and coworkers reported the synthesis of mikto-arm star-shaped aliphatic polyesters by implementing a strategy based on click chemistry (Fig. 36) [162]. Firstly, the polymerization of sCL was initiated by a diol bearing an alkyne function. The chain-ends were protected from any further undesired reaction by the esterification reaction with acetyl chloride. The alkyne was then reacted with 3-azidopropan-l-ol. The hydroxyl function located at the middle of the chain was then used to initiate the ROP of sCL and y-bromo-s-caprolactone. Finally, pendant bromides were reacted successfully with sodium azide and then with N, N-dimethylprop-2-yn-l-amine to obtain pendant amines. Under acidic conditions, pendant amines were protonated and the polymer turned out to exhibit amphiphilic properties. 

Methyl />-ethylbenzoate was prepared from ethylbenzene (1 kg.), which was converted into jb-ethylacetophenone by adding aluminum chloride (792 g.), followed by acetyl chloride (462 g.), which was added with stirring at 0-5° over a period of 3 hours. The mixture was stirred for 1 hour longer, allowed to stand overnight, and washed with iced dilute hydrochloric acid. The ethylbenzene was removed by distillation, and the crude product was oxidized to p-ethylbenzoic acid with alkaline hypochlorite.4 Recrystallization of the crude acid from 95% ethanol yielded 350 g. (41%) of the pure acid m.p. 110-112°. Esterification with methanol in the presence of hydrogen chloride 4 yielded methyl />-ethylbenzoate (77-79%). 

Detn of hydroxyl group by esterification with pure acetyl chloride, Problems of volatility and activity of reagent are surmounted)... 

The original Garner preparation3 of 5 involves the conversion of serine into the protected methyl ester 3 and controlled reduction of the latter by DIBAL. The reaction sequence employed for the preparation of 3 involves the protection of the amino acid as N-Boc derivative using di-tert-butyl dicarbonate, esterification with methyl iodide or diazomethane, and acetonization with 2,2-dimethoxypropane under acid catalysis. The N-Boc methyl serinate and the ester 3 require purification by vacuum distillation or chromatography. In a modification to this procedure reported by McKillop,2 the esterification reaction of serine is carried out first by methanol/acetyl chloride. The resulting ester is then converted into the N-Boc derivative 2 with di-tert-butyl dicarbonate and the latter transformed into 3 by acetonization. This procedure avoids... 

Iso-amyl acetate has been obtained in this way from isoamyl alcohol and acetyl chloride. The method does not offer any advantages over the more usual esterification reactions. 

It is possible to achieve selective esterification at OH-6 in good yield even with acetyl chloride by employing low temperature in the presence of a controlled amount of acylating agent.13,93 Some tin derivatives (such as dibutyltin oxide) also show significant selectivity towards position 6 (Scheme 7).94,95 A polymer-bound stannyl reagent was also applied for the selective C-6 acetylation of... 

The first step involves formation of a lactone (Sec. 10.12) and can be accomplished by heating with H+ (H2S04) as shown in eq. 10.21. The second step is an esterification. There are a number of reagents that will accomplish this transformation. One reagent would be acetic anhydride (eq. 10.39 middle). Another reagent would be acetyl chloride (eq. 10.35). 

The hydroxyl equivalent weight of epoxy resins can be determined by several methods. The most common is esterification with acids, reaction with acetyl chloride, and reaction with lithium aluminum hydride. Infrared spectroscopy may also be used. 

The hydroxyl groups are usually determined by their esterification in which the OH groups are reacted with acetic anhydride9118"120 or acetyl chloride 121 1221... 

Esterification is usually effected by refluxing the acid and alcohol with a small amount of sulfuric acid, hydrogen chloride, or arylsulfonic acid. The equilibrium is shifted to the right by an excess of one of the reactants or by removal of water either by azeotropic distillation or by means of a suitable drying agent. The necessity for continuous drying is eliminated when methylene or ethylene chlorides are used as solvents for the reaction. A small amount of an acid chloride such as thionyl chloride, acetyl chloride, or stearoyl chloride has proved superior to hydrogen chloride as a catalyst for certain esterifications at room temperature. ... 

Hydroxyl equivalent. The hydroxyl equivalent is the weight of epoxy resin containing one equivalent of hydroxyl group. It is important in calculating average molecular weights. It is determined by various methods (Lee and Nivelle, 1967), such as esterification with acids, reaction with lithium aluminium hydride, reaction with acetyl chloride and near-infra-red spectroscopy. 

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