Carbon dioxide esters

Kohlensaure,/. carbonic acid carbon dioxide, -anhydrid, rt. carbonic anhydride (carbon dioxide), -ausscheidung,/. (Physiol.) c Tbon dioxide excretion, -bestimmer, m. apparatus for determining carbon dioxide, -brot, n, aerated bread, -chlorid, n. carbonyl chloride, -entwickelung,/. evolution of carbon dioxide, -ester, m. carbonic ester, -flasche, /. carbon dioxide cylinder, -gas, n, carbonic add gas (carbon dioxide), -gehalt, m. carbon dioxide content. 

Low Molecular Weight Esters. Low molecular weight esters are important constituents of natural and artificial flavors and fragrances (56). Because of the mild reaction conditions required, enzyme catalysis is well suited for the production of these molecules. Lipase-catalyzed esterification and transesterification of terpene alcohols have been performed in solvents and in supercritical carbon dioxide. Esters of short-chain alcohols and acids were also produced in solvents and in gas/solid reactors. This last case, in which the enzyme catalyst is present in the solid form and the substrates and products are in the gas state, is especially appropriate for these highly volatile compounds (5). 

Keywords Amides Carbon dioxide Esters Hydrogen Hydrogenation Metal-hgand cooperation Pincer complexes Ruthenium... 

This tetra ethyl ester is difficult to hydrolyse the corresponding tetra-methyl ester can, however, be hydrolysed to give ethane tetracarboxylic acid, (HOOC)jCH CH(COOH)j. The latter readily loses 2 molecules of carbon dioxide (on being heated or even on boiling with water) to give succinic acid, HOOCCHjCHjCOOH. 

Alternatively, the ester may be extracted with two SO ml. portions of ether. The ethereal solution is washed with concentrated sodium bicarbonate solution (handle the separatory funnel cautiously as carbon dioxide is evolved) until effervescence ceases, then with water, and dried over anhydrous magnesium sulphate. The ether is removed with the aid of the apparatus depicted in Fig. II, 13, 4, and the residual ester distilled. 

The decomposition of a glycidic ester to an aldehyde and carbon dioxide may involve the formation of a quasi six-membered ring, followed by the shift of three electron pairs ... 

To hydrolyse an ester of a phenol (e.g., phenyl acetate), proceed as above but cool the alkaline reaction mixture and treat it with carbon dioxide until saturated (sohd carbon dioxide may also be used). Whether a solid phenol separates or not, remove it by extraction with ether. Acidify the aqueous bicarbonate solution with dilute sulphuric acid and isolate the acid as detailed for the ester of an alcohol. An alternative method, which is not so time-consuming, may be employed. Cool the alkaline reaction mixture in ice water, and add dilute sulphuric acid with stirring until the solution is acidic to Congo red paper and the acid, if aromatic or otherwise insoluble in the medium, commences to separate as a faint but permanent precipitate. Now add 5 per cent, sodium carbonate solution with vigorous stirring until the solution is alkaline to litmus paper and the precipitate redissolves completely. Remove the phenol by extraction with ether. Acidify the residual aqueous solution and investigate the organic acid as above. 

We ve seen how Grignard reagents add to the carbonyl group of aldehydes ketones and esters Grignard reagents react m much the same way with carbon dioxide to yield mag nesium salts of carboxylic acids Acidification converts these magnesium salts to the desired carboxylic acids... 

The carbon-carbon bond forming potential inherent m the Claisen and Dieckmann reac tions has been extensively exploited m organic synthesis Subsequent transformations of the p keto ester products permit the synthesis of other functional groups One of these transformations converts p keto esters to ketones it is based on the fact that p keto acids (not esters ) undergo decarboxylation readily (Section 19 17) Indeed p keto acids and their corresponding carboxylate anions as well lose carbon dioxide so easily that they tend to decarboxylate under the conditions of their formation... 

In keeping with its biogenetic origin m three molecules of acetic acid mevalonic acid has six carbon atoms The conversion of mevalonate to isopentenyl pyrophosphate involves loss of the extra carbon as carbon dioxide First the alcohol hydroxyl groups of mevalonate are converted to phosphate ester functions—they are enzymatically phosphorylated with introduction of a simple phosphate at the tertiary site and a pyrophosphate at the primary site Decarboxylation m concert with loss of the terti ary phosphate introduces a carbon-carbon double bond and gives isopentenyl pyrophos phate the fundamental building block for formation of isoprenoid natural products... 

The reaction of a vinyl ether with carbon dioxide and a secondary amine gives a carbamic ester (246). 

Oxidative Carbonylation of Ethylene—Elimination of Alcohol from p-Alkoxypropionates. Spectacular progress in the 1970s led to the rapid development of organotransition-metal chemistry, particularly to catalyze olefin reactions (93,94). A number of patents have been issued (28,95—97) for the oxidative carbonylation of ethylene to provide acryUc acid and esters. The procedure is based on the palladium catalyzed carbonylation of ethylene in the Hquid phase at temperatures of 50—200°C. Esters are formed when alcohols are included. Anhydrous conditions are desirable to minimize the formation of by-products including acetaldehyde and carbon dioxide (see Acetaldehyde). 

Hydrazine as Nucleophile. Reaction of hydrazine and carbon dioxide or carbon disulfide gives, respectively, hydrazinecarboxyhc acid [471-31-8], NH2NHCOOH, and hydrazinecarbodithioic acid [471-32-9], NH2NHCSSH, in the form of the hydrazinium salts. These compounds are useful starting materials for further synthesis. For example, if carbon disulfide reacts with hydrazine in basic medium with an alkyl haUde, an alkyl dithiocarbazate ester is obtained in a one-step reaction ... 

Hydrolysis of Peroxycarboxylic Systems. Peroxyacetic acid [79-21-0] is produced commercially by the controlled autoxidation of acetaldehyde (qv). Under hydrolytic conditions, it forms an equiHbrium mixture with acetic acid and hydrogen peroxide. The hydrogen peroxide can be recovered from the mixture by extractive distillation (89) or by precipitating as the calcium salt followed by carbonating with carbon dioxide. These methods are not practiced on a commercial scale. Alternatively, the peroxycarboxyHc acid and alcohols can be treated with an estetifying catalyst to form H2O2 and the corresponding ester (90,91) (see Peroxides and peroxy compounds). 

Other Reactions. a-Nitroalkanoic acids or thek esters can be prepared (54—56) by treating nitroparaffins with magnesium methyl carbonate, or with triisopropylaluminum and carbon dioxide. These products are reduced readily to a-amino acids. 

Chemical Properties The formation of salts with acids is the most characteristic reaction of amines. Since the amines are soluble in organic solvents and the salts are usually not soluble, acidic products can be conveniendy separated by the reaction with an amine, the unshared electron pair on the amine nitrogen acting as proton acceptor. Amines are good nucleophiles reactions of amines at the nitrogen atom have as a first step the formation of a bond with the unshared electron pair of nitrogen, eg, reactions with acid anhydrides, haUdes, and esters, with carbon dioxide or carbon disulfide, and with isocyanic or isothiocyanic acid derivatives. 

Subsequent dehydrohalogenation afforded exclusively the desired (Z)-olefin of the PGI2 methyl ester. Conversion to the sodium salt was achieved by treatment with sodium hydroxide. The sodium salt is crystalline and, when protected from atmospheric moisture and carbon dioxide, is indefinitely stable. A variation of this synthesis started with a C-5 acetylenic PGF derivative and used a mercury salt cataly2ed cyclization reaction (219). Although natural PGI has not been identified, the syntheses of both (6R)- and (65)-PGl2, [62777-90-6] and [62770-60-7], respectively, have been described, as has that of PGI3 (104,216). 

Linalool can be converted to geranyl acetone (63) by the CarroU reaction (34). By transesterification with ethyl acetoacetate, the intermediate ester thermally rearranges with loss of carbon dioxide. Linalool can also be converted to geranyl acetone by reaction with methyl isopropenyl ether. The linalyl isopropenyl ether rearranges to give the geranyl acetone. 

Telomerization Reactions. Butadiene can react readily with a number of chain-transfer agents to undergo telomerization reactions. The more often studied reagents are carbon dioxide (167—178), water (179—181), ammonia (182), alcohols (183—185), amines (186), acetic acid (187), water and CO2 (188), ammonia and CO2 (189), epoxide and CO2 (190), mercaptans (191), and other systems (171). These reactions have been widely studied and used in making unsaturated lactones, alcohols, amines, ethers, esters, and many other compounds. 

The acid chloiide (chloioformamide [463-72-9] "uiea chloiide"), NH2COCI, and its salts have been prepared. Ammonium carbamate [1111 -78-OJ can be obtained as a white crystalline sobd by reaction of dry carbon dioxide and ammonia. It is an impurity in commercial ammonium carbonate [506-87-6] (see Ammonium compounds). Esters of carbamic acid are quite stable. The best known is the ethyl ester usually called urethane [51 -79-6],... 

Carbon dioxide, the final oxidation product of carbon, is not very reactive at ordinary temperatures. However, in water solution it forms carbonic acid [463-79-6] H2CO2, which forms salts and esters through the typical reactions of a weak acid. The first ionization constant is 3.5 x 10 at 291 K the second is 4.4 x 10 at 298 K. The pH of saturated carbon dioxide solutions varies from 3.7 at 101 kPa (1 atm) to 3.2 at 2,370 kPa (23.4 atm). A soHd hydrate [27592-78-5] 8H20, separates from aqueous solutions of carbon dioxide that are chilled at elevated pressures. 

Oxidative Garbonylation. Carbon monoxide is rapidly oxidized to carbon dioxide however, under proper conditions, carbon monoxide and oxygen react with organic molecules to form carboxyUc acids or esters. With olefins, unsaturated carboxyUc acids are produced, whereas alcohols yield esters of carbonic or oxalic acid. The formation of acryUc and methacrylic acid is carried out in the Hquid phase at 10 MPa (100 atm) and 110°C using palladium chloride or rhenium chloride catalysts (eq. 19) (64,65). 

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