Acetals diacetals

Sodium hydrogen acetate (diacetate) Sodium hydrogen carbonate Sodium hydrogen (bi) sulphite... 

ACETOACETIC ESTER ACTIVE ACETYL ACETATE DIACETIC ETHER EAA ETHYL ACETOACETATE... 

Cellulose acetates. Cellulose acetate is a well-known derivative of cellulose and has found many uses as a fiber. Acetate, diacetate, and triacetate are similar in chemical structure with acetate having about 83 percent of the hydroxyl groups acetylated, and not less than 92 percent hydroxyl groups are acetylated in triacetate. Triacetate and diacetate fibers are manufactured by the acetylation of refined wood pulp or purified cotton linters. The acetylation reaction is chemically quite simple and may be visuahzed in the following manner ... 

Cyclopropane bonds are susceptible to oxidative cleavage (see Section 2.1.1.2.). Most of the oxidation reactions of activated cyclopropanes involve phenyl-substituted derivatives. When phenylcyclopropane was treated with lead(IV) acetate, 1,3-diacetoxy-l-phenylpropane (63%) and the elimination product cinnamyl acetate (32%) were obtained. The occurrence of traces of l,3-diacetoxy-2-phenylpropane could not be confirmed in later studies. The kinetics of the oxidation of various arylcyclopropanes with lead(IV) acetate, thallium(III) acetate and mercury(II) acetate have been studied. 4-Methoxyphenyl, 4-tolyl, and 4-chlorophenyl derivatives and their meta analogs were treated with these reagents and the rates of reaction and product distributions analyzed. Using lead(IV) acetate, diacetates 1 and cinnamyl acetates 2 were obtained in ratios of about 4 1, whereas thalhum(III) acetate gave the diacetates almost exclusively (see following table). ... 

Acetates. —Cupric Acetate—Diacetate— Crystals of Venus—Cupri acetas (XJ. S.)—Cu(CjHjOa)a-t-Aq—181.3- -18—is formed when UuO or verdigris is dissolved in acetic acid or by decomposition of a solution of CuSOr by PbtCa-HaOala. It crystallizes in large, bluish-green prisms, which lose their Aq at 14 0° (284° F.). At 240°-2G0° (4(>4°-500° P.) they are decomposed with liberation of glacial acetic acid. 

Foods Acid Acetate Acetate Diacetate Acid Acid Acid Acid... 

Successful results have been obtained (Renfrew and Chaney, 1946) with ethyl formate methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl and iso-amyl acetat ethyleneglycol diacetate ethyl monochloro- and trichloro-acetates methyl, n-propyl, n-octyl and n-dodecyl propionates ethyl butyrate n-butyl and n-amyl valerates ethyl laurate ethyl lactate ethyl acetoacetate diethyl carbonate dimethyl and diethyl oxalates diethyl malonate diethyl adipate di-n-butyl tartrate ethyl phenylacetate methyl and ethyl benzoates methyl and ethyl salicylates diethyl and di-n-butyl phthalates. The method fails for vinyl acetate, ieri.-butyl acetate, n-octadecyl propionate, ethyl and >i-butyl stearate, phenyl, benzyl- and guaicol-acetate, methyl and ethyl cinnamate, diethyl sulphate and ethyl p-aminobenzoate. 

I) Hydroquinone dIacetate may be prepared as follows. Add I drop of concentrated sulphuric acid to a mixture of 55 g. of hydroquinone and 103 g. (05-5 ml.) of A.R. acetic anhydride in a 500 ml. conical flask. Stir the mixture gently by hand it warms up rapidly and the hydroquinone dissolves. After 5 minutes, pour the clear solution on to 400 ml. of crushed ice. Alter with suction and wash with 500 ml. of water. Recrystallise the solid from 50 cent, ethanol by weight (ca. 400 ml. are required). The yield of pure hydroquinone diacetate, m.p. 122°, is 89 g. 

By oxidation of the methyl derivative of an aromatic hydrocarbon with a solution of chromic anhydride in acetic anhydride and acetic acid. The aldehyde formed is immediately converted into the (/m-diacetate, which is stable to oxidation. The diacetate is collected and hydrolysed with sulphuric acid, for example ... 

Equip a I litre three-necked flask with a mechanical stirrer and a thermometer, and immerse the flask in a bath of ice and salt. Place 306 g. (283 ml.) of acetic anhydride, 300 g. (285 ml.) of glacial acetic acid and 25 g. of p-nitrotoluene in the flask, and add slowly, with stirring, 42 5 ml. of concentrated sulphuric acid. When the temperature has fallen to 5°, introduce 50 g. of A.R. chromic anhydride in small portions at such a rate that the temperature does not rise above 10° continue the stirring for 10 minutes after all the chromium trioxide has been added. Pour the contents of the flask into a 3 litre beaker two-thirds filled with crushed ice and almost fill the beaker with cold water. Filter the solid at the pump and wash it with cold water until the washings are colourless. Suspend the product in 250 ml. of cold 2 per cent, sodium carbonate solution and stir mechanically for 10-15 minutes filter (1), wash with cold water, and finally with 10 ml. of alcohol. Dry in a vacuum desiccator the yield of crude p-nitrobenzal diacetate is 26 g. (2),... 

It may be converted into dibromofluorescein diacetate as follows. Reflux a mixture of 10 g. of dibromofluorescein, 40 ml. of redistilled acetic anhydride and 1 drop of concentrated sulphuric acid for 1 hour, pour into water, filter, wash, and dry the resulting diacetate (95 per cent, yield) has m.p. 210°. Upon recrystallisation from acetic anhydride or nitrobenzene, the pure diacetate (colourless or pale yellow plates), m.p. 211°, is obtained. Hydrolysis with alcoholic sulphuric acid gives a quantitative yield of pure dibromofluorescein, m.p. 285°. 

It is possible to prepare 1-acetoxy-4-chloro-2-alkenes from conjugated dienes with high selectivity. In the presence of stoichiometric amounts of LiOAc and LiCl, l-acetoxy-4-chloro-2-hutene (358) is obtained from butadiene[307], and cw-l-acetoxy-4-chloro-2-cyclohexene (360) is obtained from 1.3-cyclohexa-diene with 99% selectivity[308]. Neither the 1.4-dichloride nor 1.4-diacetate is formed. Good stereocontrol is also observed with acyclic diene.s[309]. The chloride and acetoxy groups have different reactivities. The Pd-catalyzed selective displacement of the chloride in 358 with diethylamine gives 359 without attacking allylic acetate, and the chloride in 360 is displaced with malonate with retention of the stereochemistry to give 361, while the uncatalyzed reaction affords the inversion product 362. 

The wM-diacetate 363 can be transformed into either enantiomer of the 4-substituted 2-cyclohexen-l-ol 364 via the enzymatic hydrolysis. By changing the relative reactivity of the allylic leaving groups (acetate and the more reactive carbonate), either enantiomer of 4-substituted cyclohexenyl acetate is accessible by choice. Then the enantioselective synthesis of (7 )- and (S)-5-substituted 1,3-cyclohexadienes 365 and 367 can be achieved. The Pd(II)-cat-alyzed acetoxylactonization of the diene acids affords the lactones 366 and 368 of different stereochemistry[310]. The tropane alkaloid skeletons 370 and 371 have been constructed based on this chemoselective Pd-catalyzed reactions of 6-benzyloxy-l,3-cycloheptadiene (369)[311]. 

Acetals are readily formed with alcohols and cycHc acetals with 1,2 and 1,3-diols (19). Furfural reacts with poly(vinyl alcohol) under acid catalysis to effect acetalization of the hydroxyl groups (20,21). Reaction with acetic anhydride under appropriate conditions gives the acylal, furfuryUdene diacetate... 

Nitration and halogenation of furfural occurs under carehiUy controlled conditions with introduction of the substituent at the open 5-position (24,25). Nitration of furfural is usually carried out in the presence of acetic anhydride, resulting in the stable compound, 5-nitrofurfuryhdene diacetate (26,27). The free aldehyde is isolated by hydrolysis and must be used immediately in a reaction because it is not very stable. 

Acetic anhydride adds to acetaldehyde in the presence of dilute acid to form ethyUdene diacetate [542-10-9], boron fluoride also catalyzes the reaction (78). Ethyfldene diacetate decomposes to the anhydride and aldehyde at temperatures of 220—268°C and initial pressures of 14.6—21.3 kPa (110—160 mm Hg) (79), or upon heating to 150°C in the presence of a zinc chloride catalyst (80). Acetone (qv) [67-64-1] has been prepared in 90% yield by heating an aqueous solution of acetaldehyde to 410°C in the presence of a catalyst (81). Active methylene groups condense acetaldehyde. The reaction of isobutfyene/715-11-7] and aqueous solutions of acetaldehyde in the presence of 1—2% sulfuric acid yields alkyl-y -dioxanes 2,4,4,6-tetramethyl-y -dioxane [5182-37-6] is produced in yields up to 90% (82). 

Acetylation of acetaldehyde to ethyUdene diacetate [542-10-9], a precursor of vinyl acetate, has long been known (7), but the condensation of formaldehyde [50-00-0] and acetic acid vapors to furnish acryflc acid [97-10-7] is more recent (30). These reactions consume relatively more energy than other routes for manufacturing vinyl acetate or acryflc acid, and thus are not likely to be further developed. Vapor-phase methanol—methyl acetate oxidation using simultaneous condensation to yield methyl acrylate is still being developed (28). A vanadium—titania phosphate catalyst is employed in that process. 

Acetic anhydride can be used to synthesize methyl ketones in Friedel-Crafts reactions. For example, benzene [71-43-2] can be acetylated to furnish acetophenone [98-86-2]. Ketones can be converted to their enol acetates and aldehydes to their alkyUdene diacetates. Acetaldehyde reacts with acetic anhydride to yield ethyhdene diacetate [542-10-9] (18) ... 

Unsaturated aldehydes undergo a similar reaction in the presence of strongly acid ion-exchange resins to produce alkenyUdene diacetates. Thus acrolein [107-02-8] or methacrolein [78-85-3] react with equimolar amounts of anhydride at —10°C to give high yields of the -diacetates from acetic anhydride, useful for soap fragrances. 

The reaction mechanism and rates of methyl acetate carbonylation are not fully understood. In the nickel-cataly2ed reaction, rate constants for formation of methyl acetate from methanol, formation of dimethyl ether, and carbonylation of dimethyl ether have been reported, as well as their sensitivity to partial pressure of the reactants (32). For the rhodium chloride [10049-07-7] cataly2ed reaction, methyl acetate carbonylation is considered to go through formation of ethyUdene diacetate (33) ... 

By-products remain unmentioned in most patents. Possibly there are none other than methyl acetate, acetic acid, and ethyHdene diacetate, which are all precursors of anhydride. 

Acetyl chlotide is reduced by vatious organometaUic compounds, eg, LiAlH (18). / fZ-Butyl alcohol lessens the activity of LiAlH to form lithium tti-/-butoxyalumium hydtide [17476-04-9] C22H2gA102Li, which can convert acetyl chlotide to acetaldehyde [75-07-0] (19). Triphenyl tin hydtide also reduces acetyl chlotide (20). Acetyl chlotide in the presence of Pt(II) or Rh(I) complexes, can cleave tetrahydrofuran [109-99-9] C HgO, to form chlorobutyl acetate [13398-04-4] in about 72% yield (21). Although catalytic hydrogenation of acetyl chlotide in the Rosenmund reaction is not very satisfactory, it is catalyticaHy possible to reduce acetic anhydride to ethylidene diacetate [542-10-9] in the presence of acetyl chlotide over palladium complexes (22). Rhodium trichloride, methyl iodide, and ttiphenylphosphine combine into a complex that is active in reducing acetyl chlotide (23). 

An early attempt to hydroformylate butenediol using a cobalt carbonyl catalyst gave tetrahydro-2-furanmethanol (95), presumably by aHybc rearrangement to 3-butene-l,2-diol before hydroformylation. Later, hydroformylation of butenediol diacetate with a rhodium complex as catalyst gave the acetate of 3-formyl-3-buten-l-ol (96). Hydrogenation in such a system gave 2-methyl-1,4-butanediol (97). 

With Lewis acids as catalysts, compounds containing more than one alkoxy group on a carbon atom add across vinyl ether double bonds. Acetals give 3-alkoxyacetals since the products are also acetals, they can react further with excess vinyl ether to give oligomers (228—230). Orthoformic esters give diacetals of malonaldehyde (231). With Lewis acids and mercuric salts as catalysts, vinyl ethers add in similar fashion to give acetals of 3-butenal (232,233). 

Bisa.codyl, 4,4 -(2-PyridyLmethylene)bisphenol diacetate [603-50-9] (Dulcolax) (9) is a white to off-white crystalline powder ia which particles of 50 p.m dia predominate. It is very soluble ia water, freely soluble ia chloroform and alcohol, soluble ia methanol and ben2ene, and slightly soluble ia diethyl ether. Bisacodyl may be prepared from 2-pyridine-carboxaldehyde by condensation with phenol and the aid of a dehydrant such as sulfuric acid. The resulting 4,4 -(pyridyLmethylene)diphenol is esterified by treatment with acetic anhydride and anhydrous sodium acetate. Crystallisation is from ethanol. 

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