Resorcinol acetylation

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). 

Fluororesorcinol can be prepared from derivatives of resorcinol and fluo-roxytrifluoromethane [15, 24] (equation 4) or by fluorination of resorcinol with cesium fluoroxysulfate [25] (equation 5). Reaction of acetyl hypofluorite with M-acetyl-O-methyltyrosine methyl ester provides a good route to 3-fluorotyrosine derivatives [26] (equation 6). 

Convert 3,5-dihydroxyacetophenone (5-acetyl resorcinol) to 3,5-dimethoxyacetophenone(I) in the usual way with dimethylsulfate. 

Phloroglucinol (25) is more susceptible to oxidation than both phenol and resorcinol. However, its direct nitration to 2,4,6-trinitrophloroglucinol (27) can be achieved by the slow addition of a nitrating agent composed of concentrated sulfuric acid and concentrated nitric acid to a solution of phloroglucinol dihydrate in concentrated sulfuric acid between 0 and 10 °C (72 Acetylation of phloroglucinol (25) yields the triacetate (26) which moderates... 

Resacetophenone has been prepared by heating resorcinol with zinc chloride and acetic acid,1,2 with zinc chloride and acetic anhydride,2 and with zinc chloride and acetyl chloride.3 It has also been prepared by the action of zinc chloride on resorcinol diacetate,2 by heating 4-methylumbelliferone with potassium hydroxide,4 by heating resacetophenone carbonic acid,5 and by the action of acetyl chloride on resorcinol.6... 

Golden (28) unsuccessfully attempted to prepare polymers by elimination of acetyl chloride and acetic anhydride from p-acetoxy-chlorobenzene and diacetoxybenzene, respectively. He was also unable to dehydrate hydroquinone. In the course of his study on the dehydration of phenols to aromatic ethers over thoria, Briner (8) also attempted, unsuccessfully, to dehydrate the polyphenols pyrocatechol, resorcinol and hydroquinone. 

In 1928, Schumm discovered that heating vinyl porphyrins in molten resorcinol resulted in facile loss of the vinyl groups from the porphyrins. It was subsequently shown that l -hydroxyalkyl, formyl and acetyl porphyrins behave similarly under the same conditions, i.e. these substituent groups also are removed. The Schumm devinylation reaction has been used in both synthetic and degradation studies on porphyrins, and it was stated in a paper in the Journal of Organic Chemistry that "One of the most useful reactions in the chemistry of natural porphyrins is the devinylation of vinyl porphyrins in molten resorcinol."... 

The fractions and amounts were analogous to those of Figure 2, except for the total fractions (t), where 20 pg glycolipid were used. Bands for N-acetyl (a) and N-glycoloyl (b) type of hematoside are indicated. Resorcinol was used for the detection, and the solvent war methyl acetate-2-propanol-CaClt (8 mg/mL)-NH, (5M) 45 35 15 10 (by... 

Hydroxy phenyl aceto acetate Aceto acetyl chloride + resorcinol... 

Acetylated products of the competitive reactions of equimolar proportions of o- and p-hydroxybenzyl alcohols with resorcinol were examined by 1H- and 13C-NMR in deuterochloroform. XH-NMR spectra were normalized using the relationship ... 

An emulsion polymer-isocyanate adhesive, a crosslinked polyvinyl acetate adhesive, a resorcinol-formaldehyde adhesive, a phenol-resorcinol-formalde-hyde adhesive, and an acid-catalyzed phenolic-formaldehyde adhesive developed bonds of high shear strength and wood failure at all levels of acetylation in the dry condition. A neoprene contact bond adhesive and a moisture-curing polyurethane hot-melt adhesive performed as well on acetylated wood as untreated wood in tests of dry strength. Only a cold-setting resorcinol-formal-... 

The acid reduces ammoniacal. silver nitrate solution, and with sodium nitrite gives a yellow diazo-compound, which couples with resorcinol to give a bluish-red dye. Wren dissolved in sodium hydroxide and treated with acetic anhydride, the amino-acid yields an acetyl derivative, which separates in colourless prisms from water, and yields amorphous calcium and magnesium salts. ... 

Results of a 2-year paint study indicate acetylated wood is a better painting surface (37) than untreated wood. UV radiation darkens unacetylated wood, but there is no change or a slight bleached effect with acetylated wood (37). In general, acetylation reduces the adhesive strength of wood (48). Adhesive strength is reduced with urea-formaldehyde resins (54, 55) and casein glues (55), but there is very little effect with resorcinol-formaldehyde resins (55). 

The migration of oxygen from a quaternary center in a cyclohexadienone may be preferred to a carbon shift, when present as an ether or ester function rather than free hydroxy. Thus the p-quinol acetate (117) yields the orcinol monoacetate (118 79%) on treatment at room temperature with trifluoroacetic anhydride, and the p-quinol ether (119) forms the resorcinol diethyl ether (120 71%) in ethanolic sulfuric acid. In the second case, hemiketalization must intervene also some methyl shift (12%) is observed. With the quinol (121), treatment with acetic anhydride-sulfuric acid leads to the lactone (122) acetylation or lactonization probably precedes oxygen shift. A number of related examples can be found in the steroid area. - Thermal 1,3-shifts of p-quinol acetates can also be induced acetate (117) yields catechol acetate (123 50-60%, 45 °C) by way of isomerization of the first-formed acetate (124). In the o-quinol acetate series, 1,2-acetoxy shift is seen in (125) (126 92%) and in (127) (128 90%), both in... 

Pyridine-catalyzed acylation of phenols using benzoyl chloride and benzoyl bromide was reported . Acylation of phenols using acetyl chloride or benzoyl chloride can be achieved using triflic acid as the catalyst in nonpolar solvents snch as methylene chloride. The role of pyridine in these reactions seems to be the intermittent formation of the benzoylpyrimidinium ions as the reactive species. The activated phenolic componnds snch as resorcinol, on the other hand, could be acylated in near-supercritical water (250-300 °C) without using any external Lewis acid catalysts (equation 47) . The equilibrium conversions in water, however, are to the extent of about 4%. Running the same reactions in neat acetic acid causes a tenfold increase in yield. 

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