Carbonates s. Carbonic acid esters

Carbon 27,15s31 Carbonates s. Carbonic acid esters... 

F. J. Liotta, Jr. and S. A. Schwartz. Supported carbonic acid esters useful as set accelerators and thixotropic agents in cement. Patent WO 0002828, 2000. 

In Fig. 11, at high concentrations of ethylene carbonate, the rate constants ks[EC] and kR[EC] for insertion into the EBTHI zirconaaziridine 17q are much greater than kSSR and ksss and insertion occurs more rapidly than the equilibrium can be maintained. The product ratio reflects the equilibrium of 17q, where Keq is 17.2 (Eq. 32) [21]. Beak has called this limit a dynamic thermodynamic resolution pathway [66]. In contrast, at the lowest concentration of ethylene carbonate in Fig. 10, the first-order rate constants kSSR and ksss for diastereomer interconversion are comparable to the effective first-order rate constants for insertion. As Keq is known to be 17.2, ks/kR can be calculated the 53% ee of (S)-amino acid ester 19q (Scheme 9) implies that kslkR<0.19 (Eq. 33) and that the rate constant for insertion kR[EC] into the minor diastereomer is at least five times faster than ks[EC] into the major diastereomer. 

Similarly, a 92% ee of (S)-amino acid ester 19r is obtained after the equilibrated zirconaaziridine 17r is treated with high concentrations of ethylene carbonate Keq is approximately 24.0. The reaction of equilibrated 17r with low concentrations of ethylene carbonate yields the (S)-amino acid ester 19r in 98% ee, implying that ks/kR<4.1 in this case and the rate constant of insertion ks[EC] into the major diastereomer is at least four times faster than its counterpart kR[EC] into the minor diastereomer. 

A polemic has developed in Russia on the formation and importance of the carbonic acid ester diethylpyrocarbonate in sparkling wines. Parfent ev and Kovalenko (1951, 1952) refuted Rosenfeld s (1952) concept that diethylcarbonate is only condensed carbon dioxide in alcohol. They note that it has been synthesized and its physical properties determined. Kozenko (1952) reported the amount of carbonic acid ester to be 0 in musts and to increase during fermentation. In still wines about 9 mg. per liter were found, whereas in sparkling wines 125 mg. per liter were noted. In a bottled sparkling wine 53 mg. were reported before opening, 42 mg. at 18 days after opening, 32 at 60 days, and 26 at 90 days after opening. The subject is, however, by no means settled see, for example, Merzhanian (1951, 1952). 

Protection of phenol groups as carbonic acid esters s. 18, 259... 

Reactions with active carboxylic acid esters prepared from carbonic acid esters s. 18 434 serine peptides cf. H. Voss, Z. Naturf. 20b, 122 (1965)... 

Amorphous Se added to a soln. of -butylamine in tetrahydrofuran, CO introduced, after ca. 5 min. when the Se has dissolved oxygen or air introduced simultaneously with CO for 4 hrs., then the CO-flow stopped and the Og-flow continued to precipitate Se -> l,3-di- -butylurea. Y ca. 100%. F. e., also 2-imidazolidone from ethylenediamine (cf. Synth. Meth. 3, 375), s. N. Sonoda et al.. Am. Soc. 93, 6344 (1971) sym. carbonic acid esters from alcohols in the presence of Na-alkoxide s. Tetrah. Let. 7977,4885 urethans from alcohols, amines, and CO s. Chem. Lett. 1972, 373 (Eng) carbonylation of amines in the presence of Ag-acetate, sym. ureas from prim, amines and sym. oxamides from sec. amines, s. T. Tsuda, Y. Isegawa, and T. Saegusa, J. Org. Chem. 37, 2670 (1972). 

Thiocarbonic acid esters s. (Hydroxythiol)thiono-carbonic acid esters, Thiol-, Trithio-... 

Triethylamine (s. a. under SO2CI2) Carbonic acid ester fluorides... 

Addition of carbonic acid esters to carbon-carbon triple bonds s. 13, 327 Aluminum isopropoxide Al(OR) ... 

Without additional reagents Cyclic ethers via cyclic carbonic acid esters Transesterification s. 72, 350 Thermal cleavage of dicyclopentadienes... 

The concept of the GPE was first proposed by Feuillard and Perche (1975). It contains a small amount of organic liquid known as a plasticizer, such as cyclic carbonic acid ester and chain-like ester (propylene carbonate, dimethyl carbonate, diethyl carbonate, etc.). Until now it has been the most common approach for the ion conductivity to reach the magnitude of 10" S/ cm at room temperature. Plasticizer-containing polyacrylonitrile (PAN) or poly(methyl methacrylate) (PMMA) polymer host was reported to provide... 

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