Alkyl aryl carbonates

Transesterification has become a convenient method for synthesi2ing high alkyl, aryl, or alkyl aryl carbonates. Fiber- and film-forming polycarbonates are produced by transesterifying dialkyl, dicycloalkyl, or diaryl carbonates with alkyl, cycloalkyl, or aryl dihydroxy compounds (62). 

Keywords alkyl aryl carbonate, magnesium perchlorate... 

A former approach to Boc-amino acids was based on the instability of alkyl aryl carbonates to base. Thus, by using a mixed carbonate such as 707, one should be... 

We can picture the formation of an ester as the joining of an acyl group carbon and an alkyl or aryl group carbon by way of an oxygen bridge. Either the acyl carbon or the alkyl (aryl) carbon can supply the oxygen atom. We will show examples of both methods. 

Ketenes are oxo compounds with cumulated carbonyl and carbon—carbon double bonds of the general stmcture R R2C—C—O, where and R2 may be any combination of hydrogen, alkyl, aryl, acyl, halogen, and many other functional groups. Ketenes with R = sometimes called aldoketenes,... 

The physical properties of selected carbonates are given in Table 7. The lower alkyl carbonates are neutral, colodess Hquids with a mild sweet odor. Aryl carbonates are normally soHds. 

Acid chlorides are used for the quantitative deterrnination of hydroxyl groups and for acylation of sugars. Industrial appHcations include the formation of the alkyl or aryl carbonates from phosgene (see Carbonic and chloroformic esters) and phosphate esters such as triethyl, triphenyl, tricresyl, and tritolyl phosphates from phosphoms oxychloride. 

Ester exchange of bis-alkyl or bis-aryl carbonates of dihydroxy compounds with themselves or with other dihydroxy compound. 

Detailed mechanistic studies have been carried out on aminolysis of substituted aryl acetates and aryl carbonates. Aryl esters are considerably more reactive than alkyl esters because the phenoxide ions are better leaving groups than alkoxide ions. The tetrahedral intermediate formed in aminolysis can exist in several forms which differ in extent and site of protonation ... 

Fischer-type carbene complexes, generally characterized by the formula (CO)5M=C(X)R (M=Cr, Mo, W X=7r-donor substitutent, R=alkyl, aryl or unsaturated alkenyl and alkynyl), have been known now for about 40 years. They have been widely used in synthetic reactions [37,51-58] and show a very good reactivity especially in cycloaddition reactions [59-64]. As described above, Fischer-type carbene complexes are characterized by a formal metal-carbon double bond to a low-valent transition metal which is usually stabilized by 7r-acceptor substituents such as CO, PPh3 or Cp. The electronic structure of the metal-carbene bond is of great interest because it determines the reactivity of the complex [65-68]. Several theoretical studies have addressed this problem by means of semiempirical [69-73], Hartree-Fock (HF) [74-79] and post-HF [80-83] calculations and lately also by density functional theory (DFT) calculations [67, 84-94]. Often these studies also compared Fischer-type and... 

Van Eldik attempted to achieve catalytic reactions with substituted nitrogen macrocycles and carbon dioxide but was unsuccessful in the synthesis of alkyl and aryl carbonates.458 A bridging... 

It occurs with the alkyls, aryls or acetylides of metals more electropositive than magnesium, but including Grignard reagents, and is often carried out by adding a solution of the organometallic compound in an inert solvent to a large excess of powdered, solid C02 it is a particularly useful method for the preparation of acetylenic acids. The Kolbe-Schmidt reaction (p. 291) is another example of carbanion carbonation. 

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