Diols carbonic acid esters

At temperatures around 200°, a-hydroxyacetates are transformed to oxiranes via a tautomeric ortho-monoester with neighboring-group participation. By the action of heat. CO2 is split off the carbonic acid esters of 1,2-diols and oxiranes are formed. Disecondary or ditertiary 1,2-diols react with diaryldialkoxysulfurane 66 by antiperiplanar intramolecular nucloephilic displacement via a (3-hydroxy-alkoxysulfonium ion intermediate 67 (Eq. 56). ... 

Diols and dienes from carbonic acid esters... 

Cyclic carbonic acid esters from diols... 

There are two main synthetic routes leading to five-membered cyclic carbonates the reaction of a respective oxirane with carbon dioxide or 1,2-diol with dialkyl or diphenyl carbonate. Instead of carbonic acid esters, phosgene or its derivatives can also be used. ... 

Diols from cyclic carbonic acid esters s. 16, 295 G... 

The reactions of olefins with peracids to form epoxides allows for the selective oxidation of carbon-carbon double bonds in the presence of other functional groups which may be subject to oxidation (for example, hydroxyl groups). The epoxides that result are easily cleaved by strong acids to diols or half-esters of diols and are therefore useful intermediates in the synthesis of polyfunctional compounds. 

Polycarbonates and Polyurethanes The chemistry of carbonic acid derivatives is particularly important because two large classes of polymers are bonded by linkages containing these functional groups the polycarbonates and the polyurethanes. Polycarbonates are polymers bonded by the carbonate ester linkage, and polyurethanes are polymers bonded by the carbamate ester linkage. Lexan polycarbonate is a strong, clear polymer used in bulletproof windows and crash helmets. The diol used to make Lexan is a phenol called bisphenol A, a common intermediate in polyester and polyurethane synthesis. 

Two earlier studies (Kenar et al., 2005 Knothe et al., 2000) were conducted on the effects of compounds synthesized with hydrocarbon tail-group structures resembling those of FAME with attached bulky moieties. These studies examined novel fatty diesters made from reaction of diols with acids and diacids with 2-octanol in toluene solvent with p-toluene sulfonic acid catalyst and branched-chain esters of carbonic acid (carbonates) synthesized in nonyl alcohol with n-dibutyltin oxide catalyst. None of the synthesized compounds demonstrated effectiveness in decreasing CP or PP of SME. 

R,R-diphenyl ethylene carbonate CR,R-DPEC)) with a racemic zirconaaziridine. (C2-symmetric, cyclic carbonates are attractive as optically active synthons for C02 because optically active diols are readily available through Sharpless asymmetric dihydroxylations [67].) Reaction through diastereomeric transition states affords the two diastereomers of the spirocyclic insertion product protonolysis and Zr-mediated transesterification in methanol yield a-amino acid esters. As above, the stereochemistry of the new chiral center is determined by the competition between the rate of interconversion of the zirconaaziridine enantiomers and the rate of insertion of the carbonate. As the ratio of zirconaaziridine enantiomers (S)-2/(R)-2 is initially 1 1, a kinetic quench of their equilibrium will result in no selectivity (see Eq. 32). Maximum diastereoselec-tivity (and, therefore, maximum enantioselectivity for the preparation of the... 

Aminopyrimidine-5-carboxamidcs can also be condensed with diethyl carbonate leading to pyrimido[4,5-r/]pyrimidine-2,4-diols, by treatment with sodium ethoxide/ethanol at reflux for 1 -6 hours.109 The analogous reaction with alkyl or aryl carboxylic acid esters gives alkyl- or arylpyrimido[4,5-t/]pyrimidin-4-ols 23.130... 

Two grades of fumed silica with a different degree of surface treatment and different polarity have been used a nontreated, hydrophilic Wacker HDK N20 (BET surface area 200 nP/g, 1.8 SiOH/nm equivalent to 100 % residual SiOH) and a fully silylated hydrophobic Wacker HDK H18 (carbon content 4.5 % C, 15 % residual SiOH), the latter being covered by a chemically grafted PDMS layer. Both silicas are products finom Wacker-Chemie GmbH, Germany. The resins used are an unsaturated polyester resin Palatal P4 (UP resin), a co-condensate of a diol, maleic acid and orthophthalic acid, and the vinyl ester resin Atlac 590 (VE resin), a co-condensate of glycidine, methacrylic acid and bisphenol A. Both resins have a styrene content of 35 % and are provided by DSM, The Nertherlands. 

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