Acetic anhydride, reaction with ethanol

Acetic anhydride reacts with ethanol to form ethyl acetate according to the reaction... 

Purification. Distillation is most commonly used for purifying solvents. Solvents with different vapor pressures can be separated from one another by fractional distillation. Azeotropic mixtures can be separated by extractive or azeotropic distillation (e.g., addition of benzene to a water-ethanol mixture), by chemical reaction of a component (e.g., addition of acetic anhydride to an ethanol-ethyl acetate mixture), or by altering the pressure during distillation. 

Phthalylacetic acid. Heat a mixture of 30 g. of phthalic anhydride, 40 ml. of acetic anhydride and 5 g. of potassium acetate under reflux in an oil bath at 155-165° for 15 minutes. Pour the reaction mixture into ice-cold water, collect the yellow precipitate by suction filtration, wash it three times with 25 ml. of water and once with 10 ml. of 50 per cent, ethanol. Dry the. product at 100° the yield of crude plithalylaeetie acid is 20 g. Recrystallise from hot methanol yellow needles, m.p. 245-246°, are obtained. 

Oxidation. Acetaldehyde is readily oxidised with oxygen or air to acetic acid, acetic anhydride, and peracetic acid (see Acetic acid and derivatives). The principal product depends on the reaction conditions. Acetic acid [64-19-7] may be produced commercially by the Hquid-phase oxidation of acetaldehyde at 65°C using cobalt or manganese acetate dissolved in acetic acid as a catalyst (34). Liquid-phase oxidation in the presence of mixed acetates of copper and cobalt yields acetic anhydride [108-24-7] (35). Peroxyacetic acid or a perester is beheved to be the precursor in both syntheses. There are two commercial processes for the production of peracetic acid [79-21 -0]. Low temperature oxidation of acetaldehyde in the presence of metal salts, ultraviolet irradiation, or osone yields acetaldehyde monoperacetate, which can be decomposed to peracetic acid and acetaldehyde (36). Peracetic acid can also be formed directiy by Hquid-phase oxidation at 5—50°C with a cobalt salt catalyst (37) (see Peroxides and peroxy compounds). Nitric acid oxidation of acetaldehyde yields glyoxal [107-22-2] (38,39). Oxidations of /)-xylene to terephthaHc acid [100-21-0] and of ethanol to acetic acid are activated by acetaldehyde (40,41). 

Acylation. Reaction conditions employed to acylate an aminophenol (using acetic anhydride in alkaU or pyridine, acetyl chloride and pyridine in toluene, or ketene in ethanol) usually lead to involvement of the amino function. If an excess of reagent is used, however, especially with 2-aminophenol, 0,A/-diacylated products are formed. Aminophenol carboxylates (0-acylated aminophenols) normally are prepared by the reduction of the corresponding nitrophenyl carboxylates, which is of particular importance with the 4-aminophenol derivatives. A migration of the acyl group from the O to the N position is known to occur for some 2- and 4-aminophenol acylated products. Whereas ethyl 4-aminophenyl carbonate is relatively stable in dilute acid, the 2-derivative has been shown to rearrange slowly to give ethyl 2-hydroxyphenyl carbamate [35580-89-3] (26). 

The A -oxide reactions in quinazoline 3-oxide are, however, modified to a certain extent by the aforementioned properties. Thus, whereas it can be reduced to quinazoline with phosphorus trichloride or iron and ferrous sulfate in ethanol, reactions with alkali, acetic anhydride, and benzoyl chloride in the presence of cyanide result in ring fission (Scheme 4). 

Preparation of Bisacodyl 5 grams of (4,4 -dihydroxy-diphenyl)-(pyridyl-2)-methane are heated with 5 grams of anhydrous sodium acetate and 20 cc of acetic anhydride for three hours over a boiling waterbath. The cooled reaction mixture is poured into water, whereby after a while a colorless substance precipitates, which Is filtered off with suction, washed with water and recrystallized from aqueous ethanol. Colorless bright crystals, MP 138°C are obtained. 

N 42.74% OB to C02 —30.51% cryst (meso), liq (racemic) mp 70—71° (cryst) bp 150° (decompn). Sol in acet and ethanol. Prepn is by nitration of 2,3-diazido-l, 4-butanediol with mixed acid. The procedure involves dropwise addn of 2.58g of the diol to a cooled (0—5°) mixt (1/1) of acetic anhydride/100% nitric acid. The reaction is held to 5—15° and stirred for 30 mins. Several recrysts from ethanol give a (approx) 40% yield. The compd is friction sensitive Qc 682.8 and 671.8kcal/mole Qf 98.8 kcal/mole impact sensy at 50% pt is 6.3cm using a 2kg wt in an Aberdeen Impact App and No 12 tools (PETN=26.7cm) impact sensy of proplnt films (85.15% NC/14.85% diazido compd) is 29—36cm (M2 film=34—36cm) at the 50% pt... 

Nitroimidazoles substituted by an aromatic ring at the 2-position are also active as antitrichomonal agents. Reaction of p-fluorobenzonitrile (83) with saturated ethanolic hydrogen chloride affords imino-ether 84. Condensation of that intermediate with the dimethyl acetal from 2-aminoacetaldehyde gives the imidazole 85. Nitration of that heterocycle with nitric acid in acetic anhydride gives 86. Alkylation with ethylene chlorohydrin, presumably under neutral conditions, completes the synthesis of the anti-... 

The reaction of salt 369 with acetic anhydride affords a cyclized product characterized as 2-methyl-1,3,3a,9-tetra-zacyclopentant[ ]azulene 370 (Scheme 38) <1999J(P1)1339>. The reaction of l,2-diamino-l,3-diazaazulenium compound 369 with diethyl ethoxymethylenedicarboxylate (DEEM) provides a complex reaction mixture, one of the isolated products being compound 21, which is isolated in 29% yield when the reaction is carried out in ethanol, but in 47% yield, when acetonitrile is used as solvent (Scheme 38) <1999J(P1)1339>. 

The nitrolysis of hexamine at low temperature has led to the synthesis of a number of cyclic nitramines. The reaction of hexamine dinitrate (241) with 88 % nitric acid at -40 °C, followed by quenching the reaction mixture onto crushed ice, leads to the precipitation of 3,5-dinitro-3,5-diazapiperidinium nitrate (242) (PCX) in good yield PCX is an explosive equal in power to RDX but is slightly more sensitive to impact. The reaction of PCX (242) with sodium acetate in acetic anhydride yields l-acetyl-3,5-dinitro-l,3,5-triazacyclohexane (82) (TAX), which on further treatment with dilute alkali in ethanol yields the bicycle (243). ... 

The reaction of hexamine dinitrate (241) with 98% nitric acid at —30°C, followed by quenching with aqueous sodium nitrate, yields the nitrosamine (244). When the same reaction is cautiously quenched with ethanol the ethoxyether (245) is obtained. Treatment of the ethoxyether (245) with cold absolute nitric acid yields the bicyclic ether (246). ° Treatment of any of the cyclic nitramines (242)-(246) with nitric acid and ammonium nitrate in acetic anhydride yields RDX. ° Hexamine dinitrate is often used in low temperature nitrolysis experiments in order to avoid the initial exotherm observed on addition of hexamine to nitric acid. 

When the 3-thiourea derivative (59) was heated in boiling ethanol for 3 h, and then the evaporated reaction mixture was treated with 10% NaOH solution at 100°C for 20 min, anhydro 2-methyl-3-mercapto-4-hydroxy-5,6,7,8-tetrahydro[l,2-6]pyridazinium hydroxide (61) was obtained (71CPB159). The mercapto group was alkylated with benzyl bromide and was treated with HgCla in boiling ethanol to yield the 3-chloromercurithio derivative. Anhydro 3,4-dihydroxy-2-methyl-5,6,7,8-tetrahydropyrido[l,2-f ]pyridazinium hydroxide (62) was O-acylated with acetic anhydride, but the structure of the product was not elucidated (71CPB159). 

Preparation of nitrile acetates from oximes with sodium acetate and acetic anhydride. Pentaacetyl-v-glucononitrile. If only the nitrile is needed, isolation of the oxime can be avoided. One hundred grams of anhydijous n-glucose was dissolved in 50 ml. of warm water, and maintaining the temperature at 60°, a solution of 28 g. of hydro-xylamine in 700 ml. of ethanol was added sufficiently slowly that no precipitation took place. After one hour at 65°, the reaction mixture was concentrated under reduced pressure to a thick sirup. The residue was mixed with absolute ethanol, the ethanol evaporated and the operation repeated in order to eliminate all water. One hundred and twenty grams of anhydrous sodium acetate and 700 ml. of acetic anhydride were added to the sirup, and the mixture was slowly and cautiously warmed in a water bath to 95°. It was advisable to agitate the flask continuously and to watch the... 

Concurrent with acetic anhydride formation is the reduction of the metal-acyl species selectively to acetaldehyde. Unlike many other soluble metal catalysts (e.g. Co, Ru), no further reduction of the aldehyde to ethanol occurs. The mechanism of acetaldehyde formation in this process is likely identical to the conversion of alkyl halides to aldehydes with one additional carbon catalyzed by palladium (equation 14) (18). This reaction occurs with CO/H2 utilizing Pd(PPh )2Cl2 as a catalyst precursor. The suggested catalytic species is (PPh3)2 Pd(CO) (18). This reaction is likely occurring in the reductive carbonylation of methyl acetate, with methyl iodide (i.e. RX) being continuously generated. 

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