Acetic anhydride with ethers

It is not customary to attempt the isolation of ketone or aldehyde intermediates (121) the formula serves merely as a reminder that once hydrolysis of the protecting enol ether or acetal occurs, the same type of structure is formed from any given dicarbonyl compound. Cyclization has been carried out in refluxing ethanolic picric acid or acetic anhydride with a few drops of sulfuric acid, but Hansen and Amstutz (63JOC393) offered excellent theoretical reasons for avoiding an excess of acid, and reported that best results (Table 3) can be obtained by refluxing the dry hydrobromide in acetic anhydride containing no sulfuric acid. 

N 20.89%, OB to C03 minus 59-7% crysts (from ether), mp 103—104°(Ref 2). It was prepd by Blomquist 8c Fiedorek by dehydration of N,N-di(/)-nitroxypropyl)-armne nitrate on heating at 40—45° with acetic anhydride with small amt-of HC1, followed by addition of chloride catalyst such as Zn chloride (Refs 2 St 3)... 

Acetoxy-5-bromo-6/9,19-epoxy-5a -androstan-17-one undergoes rearrangement in acetic anhydride with BF3 diethyl etherate to give 3/2,19-diacetoxy-6o -bromo-5-hydroxy-5/l-androst-l 7-one after the addition of water, as shown schematically in Scheme 23.40... 

Alternatively, direct electrophilic acylation of a BIPS also occurred in the 3-position. Vilsmeier formylation of 6-nitroBIPS gave 22% of the 3-formyl derivative (113, R=H) acetic anhydride with boron trifluoride etherate in chloroform solvent gave 56% of the 3-acetyl compound (113, R=Me) and benzoyl chloride with aluminium bromide in carbon disulfide solvent gave 26% of 3-benzoyl-6-nitroBIPS (113, R=Ph). None of the 3-acyl BIPS showed any coloration upon UV irradiation in any solvent.106... 

Formation of substituted products by electrophilic reactions is one of the characteristics of benzenoid compounds. It has been shown that a few dehydro-[4/j + 2]annulenes afford substituted annulenes under strictly limited reaction conditions. Monodehydro[14]annulene, on treatment at room temperature with copper(ii) nitrate-acetic anhydride, oleum-dioxane and subsequent methylation and acetic anhydride-borontrifluoride etherate, yielded monosubstituted products, 169a, 169b and 169c, respectively. The electrophilic reactions must have resulted in substitution of one of the outer protons, but the exact point of attack has not been determined . 

Note that acetic acid is eliminated during the reaction. What effect would sodium acetate have How might boron fluoride etherate or sulfuric acid affect the nucleophilic attack of the phenolic oxygen on acetic anhydride With what might the base, pyridine, associate ... 

Lithium bromide-Boron trifluoride etherate. Aliphatic ethers can be cleaved by reaction with lithium bromide and boron trifluoride etherate in acetic anhydride at room temperature for 30 hrs. Methoxycyclohexane, for example, is converted into a 7 1 mixture of acetoxycyclohexane and cyclohexene. Saturated steroid ethers are cleaved to mixtures of enes and acetates under these conditions choles-teryl methyl ether gave about equal parts of cholesteryl acetate and cholesteryl bromide. However, Narayanan reports that the lithium halide is not essential and indeed often detrimental. Thus cholesteryl methyl ether treated with boron trifluoride etherate and acetic anhydride in ether at 0° (14 hrs.) gave cholesteryl acetate in 93% yield. 

NITRATO SODICO (Spanish) (7631-99-4) Noncombustible, but enhances the combustibility or oxidation rate of many materials chemical reactions can cause fire and explosions. Elevated temperatures above 716°F/380 C cause ignition explodes above 1000°F/537°C. A powerful oxidizer. Reacts violently with many materials, including reducing agents, combustible substances, strong acids, organic substances, powdered metals, alcohols, acetic anhydride, bitumens, ethers, glycols. Reacts with acrolein, antimony trisulfide, antimony tritelluride, arsenic pentasulfide, boron phosphide, cyanides, 1,1-dichloro-l-... 

A mixture of 10.2 g. of Zn(N03)s 6H3O and 40 ml. of acetic anhydride is heated. When the vigorous reaction ceases, the mixture is stored in the cold for some time the crystal slurry is then suction-filtered, washed with some acetic anhydride and ether, and dried in vacuum over KOH and HaS04. Yield 95%. 

A mixture of 5 g. of Cd(N03)g 4 HgO and 25 ml. of acetic anhydride is heated when the vigorous reaction has ceased, the mixture is refluxed 15 minutes. After cooling and suctionfiltering, the white, crystalline precipitate is washed with some acetic anhydride and ether, and vacuum-dried over KOH and HgS04. Yield 3.6 g. (97%). 

An ethereal soln. of dineopentyl ketone added during 2 hrs. to 2,4,6-trimethyl-phenylmagnesium bromide prepared from bromomesitylene and Mg in ether, refluxed 2 hrs., then acetic anhydride in ether added during 2 hrs. with icecooling, and stirring continued 1 hr. - 2,2,6,6-tetramethylhept-3-en-4-yl acetate. Y 90%. F. e. s. H. G. Hauthal, P. Kluge, and H. Schmidt, J. pr. 29, 296 (1965). 

Once our purified dicarboxylic acid monomer had been synthesized, isolated and purified, the mixed anhydride was prepared (Examples 2 and S). The mixed anhydride is synthesized by reacting acetic anhydride with the acid monomer at reflux for several hours under a nitrogen atmosphere followed by removal of a portion of the acetic anhydride. The homogeneous solution was then allowed to crystallize at 0°C overnight, filtered, and then washed with dry ethyl ether to remove traces of acetic anhydride. The mixed anhydride was then filtered, and dried for 24 hours at low temperature (50 C) under vacuum to yield the highly pure anhydride monomer. Recrystallization with acetic anhydride was also performed (Example 5). 

Obtained by reaction of acetic anhydride with 4,6-dimethyl-resorcinol in the presence of 45% solution of boron trifluoride etherate at r.t. (15%) [2213] or boron trifluoride-acetic acid complex for 2 h at 100° [2997],... 

Obtained by reaction of acetic anhydride with l-bromo-2,4-dimethoxybenzene in the presence of boron triflnoride etherate in methylene chloride first at 0°, then at r.t. for 24 h (85%) [3830],... 

Also obtained by reaction of acetic anhydride with resorcinol dimethyl ether in the presence of aluminium chloride in carbon disulfide (77-80%) [3966], at r.t., then at 30-35° until no more hydrochloric acid [3796,3797]. 

Tertiary alcohols have been esterified in good yield using acetic anhydride with calcium hydride or calcium carbide. f-Butanol can be esterified to f-butyl acetate in 80% yield under these conditions. High pressure (15 kbar) has been used to introduce the acetate group using acetic anhydride in methylene chloride. Yields range from 79-98%. Chemoselectivity is achieved using acetic anhydride and boron trifluoride etherate in THF at 0 °C. Under these conditions, primary or secondary alcohols are acetylated in the presence of phenols. ... 

For 30-45 minutes reflux 2 ml of acetic anhydride with 1 g of the add. Cool and wash the precipitate with a little dry ether. As a further check use the anhydride, dissolved in benzene and heated briefly with a benzene (or chloroform) solution of 1 ml of aniline, to prepare the anilic acid. Cool, and wash the solid with a little benzene. (See Table 9.)... 

When the reaction has subsided, boil the reaction-mixture under reflux for 2 hours then make it alkaline with sodium hydroxide solution, and distil it in steam until oily drops no longer come over in the aqueous distillate (1 2 litres). Extract the distillate thoroughly with ether ca. 150 ml.), and dry the ethereal extract over powdered sodium hydroxide. Filter the dry extract through a fluted filter-paper moistened with ether into a 200 ml. flask. Fit the flask with a distillation-head, or a knee-tube , and distil off the ether. Now replace the distillation-head by a reflux water-condenser, add 10 ml. of acetic anhydride, and boil the mixture under reflux for 10 15 minutes. 

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