Benzoic-carbonic anhydride

B. Mixed benzoic-carbonic anhydride (Note 7). In a 500-ml. threenecked flask, equipped with a low-temperature thermometer, an efficient sealed stirrer, and an adaptive joint carrying a drying tube and a dropping funnel, is placed a solution of 24.4 g. (0.2 mole) of benzoic acid (Note 8) and 20.2 g. (0.2 mole) of triethylamine (Note 9) in 200 ml. of dry toluene. The solution is cooled below 0° by means of an ice-salt mixture, and 21.7 g. (0.2 mole) of ethyl chlorocarbonate (Note 10) is added at such a rate that the temperature does not rise above 0° (approximate time for addition is 25-30 minutes). Triethylamine hydrochloride precipitates both during the addition and while the mixture is stirred for 15-25 minutes thereafter. 

Benzoylation, of o-hydroxy-acetophenone, 32, 72 of malonic ester, 37, 20 with benzoic-carbonic anhydride,... 

Mixed anhydride synthesis. A method widfely used for the synthesis of peptides provides a general method of acylation, illustrated by the benzoylation of diethyl malonate. Benzoic acid is converted into the triethylamine salt in toluene, and the solution is treated at 0 with ethyl chloroformate to form the mixed benzoic-carbonic anhydride, with precipitation of triethylamine hydrochloride. The second component, ethoxymagnesium malonic ester, is prepared from diethyl malonate in ethanol-ether... 

In the studies of the synthesis of the ansamycin antibiotic rifamycin S (13S), Corey and Clark [76] found numerous attempts to effect the lactam closure of the linear precursor 132 to 134 uniformly unsuccessful under a variety of experimental conditions, e.g. via activated ester with imidazole and mixed benzoic anhydride. The crux of the problem was associated with the quinone system which so deactivates the amino group to prevent its attachment to mildly activated carboxylic derivatives. Cyclization was achieved after conversion of the quinone system to the hydroquinone system. Thus, as shown in Scheme 45, treatment of 132 with 10 equiv of isobutyl chloroformate and 1 eqtuv of triethylamine at 23 °C produced the corresponding mixed carbonic anhydride in 95% yield. The quinone C=C bond was reduced by hydrogenation with Lindlar catalyst at low temperature. A cold solution of the hydroquinone was added over 2 h to THF at 50 °C and stirred for an additional 12 h at the same temperature. Oxidation with aqueous potassium ferricyanide afforded the cyclic product 134 in 80% yield. Kishi and coworkers [73] gained a similar result by using mixed ethyl carbonic anhydride. 

The only anhydrides for which kinetic data are available in solution are the carbonic anhydrides. The decomposition of benzoic n-butyl carbonic anhydride... 

Extensive use of mixed anhydrides of carbonic acids has been made in peptide synthesis. Polymer-based mixed carbonic anhydrides prepared by Shambhu and Digenis (1974) and Martin et al. (1978a) gave exclusively the amide of benzoic acid with aliphatic amines [Eq. (4)], but with aniline, some polymeric urethane was also formed. 

Benzoic acid anhydride w ith ethyl hydrogen carbonate, 9CI [3741-66-0]... 

Benzoic acid anhydride with ethyl hydrogen carbonate, see B-00067 Benzoic acid [l-[2-(4-bromo-2-nitrophenyl) hydrazino]ethylidene]hydrazide, B-00060 Benzoic acid 1,2-... 

An equimolar amount of BFg-etherate added to benzoic ethyl carbonic anhydride ethyl benzoate. Y excellent. F. e. s. T. B. Windholz, J. Org. Chem. 25, 1703 (1960). 

The kinetics of nitration of benzene in solutions at c. 20 °C in carbon tetrachloride have been investigated. In the presence of an excess of benzene (c. 2-4 mol 1 ) the rate was kinetically of the first order in the concentration of benzoyl nitrate. The rate of reaction was depressed by the addition of benzoic anhydride, provided that some benzoic acid was present. This result suggested that benzoyl nitrate itself was not responsible for the nitration, but generated dinitrogen pentoxide... 

Because of the chemical similarity between benzoyl nitrate and the acetyl nitrate which is formed in solutions of nitric acid in acetic anhydride, it is tempting to draw analogies between the mechanisms of nitration in such solutions and in solutions of benzoyl nitrate in carbon tetrachloride. Similarities do exist, such as the production by these reagents of higher proportions of o-substituted products from some substrates than are produced by nitronium ions, as already mentioned and further discussed below. Further, in solutions in carbon tetrachloride of acetyl nitrate or benzoyl nitrate, the addition of acetic anhydride and benzoic anhydride respectively reduces the rate of reaction, implying that dinitrogen pentoxide may also be involved in nitration in acetic anhydride. However, for solutions in which acetic anhydride is also the solvent, the analogy should be drawn with caution, for in many ways the conditions are not comparable. Thus, carbon tetrachloride is a non-polar solvent, in which, as has been shown above,... 

Henkel Rearrangement of Benzoic Acid and Phthalic Anhydride. Henkel technology is based on the conversion of benzenecarboxyhc acids to their potassium salts. The salts are rearranged in the presence of carbon dioxide and a catalyst such as cadmium or zinc oxide to form dipotassium terephthalate, which is converted to terephthahc acid (59—61). Henkel technology is obsolete and is no longer practiced, but it was once commercialized by Teijin Hercules Chemical Co. and Kawasaki Kasei Chemicals Ltd. Both processes foUowed a route starting with oxidation of napthalene to phthahc anhydride. In the Teijin process, the phthaHc anhydride was converted sequentially to monopotassium and then dipotassium o-phthalate by aqueous recycle of monopotassium and dipotassium terephthalate (62). The dipotassium o-phthalate was recovered and isomerized in carbon dioxide at a pressure of 1000—5000 kPa ( 10 50 atm) and at 350—450°C. The product dipotassium terephthalate was dissolved in water and recycled as noted above. Production of monopotassium o-phthalate released terephthahc acid, which was filtered, dried, and stored (63,64). 

Ingold et al." showed that rates of nitration by benzoyl nitrate in carbon tetrachloride were depressed by the addition of benzoic anhydride. Thus addition of 0.035 M of the anhydride to a solution 2.36 M in benzene and 0.030 M in nitrate decreased the first-order rate coefficient from 44x 10-4 to 20xl0-4. This is consistent with nitration by dinitrogen pentoxide formed via equilibrium (37), viz. 

DPA) in dimethylphthalate at about 70°, yields a relatively strong blue Umax =435 nm) chemiluminescence the quantum yield is about 7% that of luminol 64>. The emission spectrum matches that of DPA fluorescence so that the available excitation energy is more than 70 kcal/mole. Energy transfer was observed on other fluorescers, e.g. rubrene and fluorescein. The mechansim of the phthaloyl peroxide/fluorescer chemiluminescence reaction very probably involves radicals. Luminol also chemiluminesces when heated with phthaloyl peroxide but only in the presence of base, which suggests another mechanism. The products of phthaloyl peroxide thermolysis are carbon dioxide, benzoic acid, phthalic anhydride, o-phenyl benzoic acid and some other compounds 65>66>. It is not yet known which of them is the key intermediate which transfers its excitation energy to the fluorescer. 

Dissolve 8.66 g ecgonine in 100 ml methanol and bubble dry HCI gas through for Vi hour. Let stand two hours at room temperature and then reflux gently for V2 hour. Evaporate in vacuum, basify with NaOH and filter to get 8.4 g methylecgonine (V) (recrystallize-isopropanol). 4.16 g (V) and 5.7 g benzoic anhydride in 150 ml benzene with CaCI2 tube to exclude water and gently reflux four hours. Cool in ice bath, acidify with HCI and dry, evaporate in vacuum (or extract with ether, basify with NaOH, saturate with K carbonate and extract with CHCl3 dry and evaporate in vacuum) to get 6 g red oil which precipitates (VI) with addition of a little isopropanol. 

Contact time between the reactants and the catalyst is about a tenth of a second. The reaction gases—mainly phthalic anhydride, carbon dioxide, and water—are cooled, condensed, and purified in stainless steel facilities. Phthalic anhydride solidifies at 269°Fj so the purified (99.5%) product can be stored in its molten form or cooled and flaked. Minor amounts of by-products, maleic anhydride, phthalic acid, and benzoic acid are also produced. 

Formerly, benzoic acid was produced by the decarboxylation of phthalic anhydride. Oxidation of acetophenon, benzyl bromide, and toluene with sulfur and water has been described in the literature, but are not commercially feasible routes of synthesis. Carboxylation of benzene with carbon dioxide is not practical due to the instability of benzoic acid at the required reaction conditions [8]. 

When benzoic acid is heated above its melting point in a sealed container, some formation of benzoic anhydride and water takes place [8]. When the acid is heated to 370°C, it is irreversibly decomposed to benzene and carbon dioxide, and a small portion (2-8%) decomposes into phenol and carbon monoxide. Copper and cadmium powder increase the reaction rate by factors of approximately 9-fold and 200-fold, respectively. 

The gas-phase selective oxidation of o-xylene to phthalic anhydride is performed industrially over vanadia-titania-based catalysts ("7-5). The process operates in the temperature range 620-670 K with 60-70 g/Nm of xylene in air and 0.15 to 0.6 sec. contact times. It allows near 80 % yield in phthalic anhydride. The main by-products are maleic anhydride, that is recovered with yields near 4 %, and carbon oxides. Minor by-products are o-tolualdehyde, o-toluic acid, phthalide, benzoic acid, toluene, benzene, citraconic anhydride. The kinetics and the mechanism of this reaction have been theobjectof a number of studies ( 2-7). Reaction schemes have been proposed for the selective pathways, but much less is known about by-product formation. 

The acylation of formamidoxime should lead to oxadiazoles unsubstituted in the 3-position. While benzoylation with benzoyl chloride is reported to give dibenzhydroxamic acid 45), 0-acylated formamidoxime could be prepared in good yields with acetic anhydride, the mixed anhydride of acetic and ethyl carbonic acid, benzoic anhydride and benzoyl azide. The cyclization of these esters of formamidoxime into 5-substituted oxadiazoles has been accomplished by heating in an aqueous medium. 

Benzoic anhydride has been prepared in rather a poor yield by the action of benzoyl chloride on sodium benzoate,2 barium oxide at 1500,3 benzoic acid at 160-200°,4 sodium nitrite,5 lead nitrate,6 or anhydrous oxalic acid 7 also by treating sodium benzoate with phosphorus pentachloride8 or sulfur chloride.9 More important methods consist in treating benzotrichloride with sulfuric acid,10 and in the action of sodium carbonate upon benzoyl chloride in presence of pyridine.11... 

The method described is adapted from the procedures of Kym 3 and Engelhardt, Latschinoff, and Malyscheff.4 Thio-benzoic acid has been prepared by the reaction of benzoyl chloride with potassium sulfide,4 hydrogen sulfide in pyridine,6 6 and magnesium bromide hydrosulfide.7 It is formed from dibenzoyl disulfide with potassium hydrosulfide,4 potassium hydroxide,4 8 and ammonia.9 It is also formed from dibenzoyl sulfide, from phenyl benzoate, and from benzoic anhydride with alcoholic potassium hydrosulfide.4 It has been obtained from dibenzoyl sulfide and hydrogen sulfide,10 carbon oxysulfide and phenyl-magnesium bromide,11 12 dibenzyl disulfide and sodium ethoxide,13 benzyl chloride and sulfur in the presence of potassium hydroxide,14 and benzylthiosulfuric acid and alkali.18 16... 

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