Acetaldehyde dimethyl acetal

Acetals and Acylals. Acetals, which contain the group >C(OR)2, where R may be different, are named (1) as dialkoxy compounds or (2) by the name of the corresponding aldehyde or ketone followed by the name of the hydrocarbon radical(s) followed by the word acetal. For example, CH3—CH(0CH3)2 is named either (1) 1,1-dimethoxyethane or (2) acetaldehyde dimethyl acetal. 

Acetaldehyde ammonia, al62 Acetaldehyde diethyl acetal, d303 Acetaldehyde dimethyl acetal, d504... 

B. (4R,5S)-3-(1-Methoxyethyl)-4,5-diphenyl-2-oxazolidinone. A 2-L, threenecked, round-bottomed flask equipped with a magnetic stirrer, thermometer, and a reflux condenser is charged with (4R,5S)-4,5-diphenyl-2-oxazolidinone (20.0 g, 84 mmol), ( )-10-camphorsulfonic acid (9.7 g, 42 mmol) (Note 7), and acetaldehyde dimethyl acetal (700 mL) (Note 8). The mixture is heated at gentle reflux in an oil bath (bath temperature 80°C) for 5 hr (Note 9). The mixture is allowed to cool to ambient temperature, then concentrated under reduced pressure on a rotary evaporator (Note 10). Ethyl acetate (100 mL) is added to the residue, and the ethyl acetate solution is transferred to a beaker. The solution is neutralized with saturated sodium bicarbonate solution (100 mL) (Note 11), and transferred into a separatory funnel. The two layers are separated, and the lower aqueous layer is extracted with ethyl acetate (100 mL). 

Acetaldehyde dimethyl acetal was purchased from Tokyo Kasei Kogyo Co., Ltd. It is also available from Aldrich Chemical Company, Inc. 

Excess acetaldehyde dimethyl acetal can be recovered by distillation. 

Methanolysis of 9-(l-methoxyethyl)carbazole with methanol-hydrogen chloride gave carbazole and acetaldehyde dimethyl acetal. 9,9 -Di-(3,6-dibromocarbazolyl)methane gave 9-acetyl-3,6-dibromocarbazole with acetic anhydride and a trace of sulfuric add. ... 

Acetaldehyde dimethyl acetal [534-15-6] M 90.1, b 63-65°, dj0 0.852, n 51.36678. Distd through a fractionating column and fraction boiling at 63.8°/751mm is collected. It forms an azeotrope with MeOH. 

The PPA-promoted cyclizations of (phenylthio)acetaldehyde dimethyl acetal and a-(phenylthio)propionaldehyde diethyl acetal yield benzo[6]thiophene together with 3-methoxy-2,3-dihydrobenzo-[6]thiophene, and a mixture of 2- and 3-methylbenzo[6]thiophene, respectively.296 Mechanisms have been proposed to account for these results. 

Nitrobenzo[6]thiophene is obtained in 10% yield by the cycliza-tion of (p-nitrophenylthio)acetaldehyde dimethyl acetal (Section IV,B) 7-nitrobenzo[6]thiophene cannot be prepared by this method.488 5-Nitrobenzo[6]thiophene84,218,338,422,538,543-545 and its 3-phenyl,333 3-methyl,298 3,6-dimethyl,330 and 7-nitro-3-phenyl334 derivatives may be obtained most conveniently by decarboxylation of the readily available (Section IV, D) 2-carboxylic acids. 5- 4 J4.54e 0. 494,548 an(j 7.494 nitro-3-acetoxybenzo[6]thiophene may be prepared almost quantitatively by cyclization reactions (Section IV, D). 

Hydroxybenzo[6]thiophene has been isolated from coal tar.42 It may be prepared from 6-aminobenzo[fr]thiophene by standard procedures.241 6-Methoxybenzo[h]thiophene may be prepared by decarboxylation of the corresponding 2-carboxylic acid,341 and 6-ethoxybenzo[6]thiophene is obtained by reduction of 6-(ethoxy)-thioindoxyl (Section VI, 1,2). 6-Methoxy-5-methylbenzo[6]thiophene is obtained by cyclization of (3-methoxy-4-methylphenylthio)-acetaldehyde dimethyl acetal (Section IV,B).617 The product previously described542 as 6-hydroxy-3-phenylbenzo[6]thiophene has now been shown to be the 2-phenyl isomer.307 6-Methoxy-818 and 6-methoxy-5-methyl-benzo[6]thiophene617 are demethylated by pyridine hydrochloride. 

Methoxybenzo[6]thiophene may be prepared by cyclodehydration of (o-methoxyphenylthio)acetaldehyde dimethyl acetal (Section... 

Acetaldehyde ammonia, al63 Acetaldehyde diethyl acetal, d251 Acetaldehyde dimethyl acetal, d438 Acetamidoacetic acid, a46 2-Acetamidopentanedioic acid, a45... 

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