Carbon dioxide compounds dimer

Wyman, Allen and Altares (20) reported that the carbonation of poly-(styryl)lithium in benzene with gaseous carbon dioxide produced only a 60% yield of carboxylic acid the acid was contaminated with significant amounts of the corresponding ketone (dimer) and tertiary alcohol (trimer) as shown in eq. 6. A recent, careful, detailed investigation of the carbonation of polymeric organolithium compounds has... 

Biological. 1-Naphthylamine added to three different soils was incubated in the dark at 23 °C under a carbon dioxide-free atmosphere. After 308 d, 16.6 to 30.7% of the 1-naphthylamine added to soil biodegraded to carbon dioxide (Graved et al., 1986). Li and Lee (1999) investigated the reaction of 10 mL of 7 mM 1-naphthylamine with 4 g of a Chalmers soil (pH 6.5, 11.1% sand, 72.8% silt, 16.0% clay). After 120 h, the soil was washed with acetonitrile and the extractant analyzed using GC/MS. The primary transformation product was a dimer tentatively identified as TV-(4-aminonaphthyl)-1-naphthylamine. The investigators hypothesized that the formation of this compound and two other unidentified dimers was catalyzed by minerals present in the soil. 

Another type of elimination reaction favoured under plasma conditions is the decarboxylation. Carbocyclic acids easily lose carbon dioxide to form the parent hydrocarbons. In acid anhydrides decarboxylation is followed by a decar-bonylation. Cyclic or bicyclic anhydrides fragment forming unsaturated compounds, a reaction which has been studied with phthalie anhydride 24>. This anhydride decomposes to dehydrobenzene which, in the absence of other compounds, dimerizes, trimerizes or polymerizes. Orientation experiments indicated similar results for aliphatic acid anhydrides. 

Anhydro-5-hydroxyoxazolium hydroxides lacking substituents at C(4) dimerize spontaneously by a process in which one molecule acts as an electrophile and the other as a nucleophile (Scheme 21). This accounts for the fact that dimeric products of this type are obtained by the action of dicyclohexylcarbodiimide on acylamino acids of the general formula R1C0NR2CH2C02H. Substituents at position 4 stabilize the mesoionic system the first compounds to be prepared were the acetyl derivatives (220) (B-49MI41800) and (221) (58Cl(L)46l) and much of the more recent work has been carried out with the relatively stable methyldiphenyl compound (222). This miinchnone decomposes above 115 °C to yield the allene (225) with loss of carbon dioxide. The mechanism proposed for this remarkable reaction (Scheme 22) involves valence isomerization to the ketene (223), which undergoes a 1,3-dipolar cycloaddition with the miinchnone. The product loses carbon dioxide to form a new betaine (224), which collapses to the allene as shown. 

Many compounds [olehns, alcohols, and carboxyhc acids (or other carbonyl chemistry)] will undergo dimerization reactions. Figure A15-7 shows how carboxylic acids can react with an alcohol to form a dimer [6] (note that it should be loss of water and not carbon dioxide). In RP-UPLC under basic conditions, the elution order would be dihunisal in its ionized form < descarboxydiflunisal < the dimer. Indoles have been shown to dimerize under acidic conditions, and phenols have shown to dimerize under free radical initiated oxidative conditions, usually ortho-phenols [1]. Due to the low bond dissociation energy of the benzylic C-H bond and ease of radical formation, dimerization can occur at the benzylic center. Nalidixic acid undergoes dimerization under thermolysis conditions to produce a dimeric structure [26]. 

Compounds whose radical anions give follow-up reactions can be reduced, and the reaction medium (aqueous or non-aqueous) eventually governs the nature of the final products. A number of organic substrates such as aldehydes, ketones and alkynes have been reduced in this way. It is also possible to reduce substrates which have a potential much more negative than its standard redox potential. For instance, nitrate, nitrite and carbon dioxide are reduced [2]. In the latter case [157], the overpotential reaches 0.6 V and the reaction is still rapid because the rate of the follow-up reaction, i.e. the dimerization of C02 , is extremely high (it= 10 M- s- ) [158]. 

Amino acids may also be prepared from azomethine compounds by reducing them in the presence of carbon dioxide [34—38]. Thus reduction of benzylidene aniline (IV) in molten tetraethylammonium -toluenesulfonate saturated with carbon dioxide at 140°C gave V-phenyl-phenylglycine (60% yield) [34], [Eq. (9)]. In DMF a similar yield was obtained together with small amounts of a dimer and some phenylbenzylamine [38]. 

Photochemical (2 + 2)-cycloreversions of heterocyclic compounds are rare. The dimer of xanthotoxin, a naturally occurring furocoumarin, was reported to undergo a photochemical (2 + 2)-cycloreversion upon irradiation (A > 250 nm).137 Irradiation of 2-oxabicyclo[2.2.0]hex-5-ene-3-ones (224) at temperatures of 8° to 20° K resulted in the elimination of carbon dioxide [Eq. (12)].12,307 Similarly, pyridine was found to give... 

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