Anhydrides esters

Although the reaction is a general one for aldehydes and ketones, in certain instances, esters, anhydrides, and nitrites are attacked by these reagents (8,92). 

Both singlet and triplet n,n states undergo the reaction." The intermediate diradical can also cyclize to a cyclobutanol, which is often a side product. Carboxylic esters, anhydrides, and other carbonyl compounds can also give this... 

Polymers used in medicine fall into two main categories those that are sufficiently inert to fulfill a long-term structural function as biomaterials or membranes, and those that are sufficiently hydrolytically unstable to function as bioeradible materials, either in the form of sutures or as absorbable matrices for the controlled release of drugs. For the synthetic organic polymers widely used in biomedicine this often translates to a distinction between polymers that have a completely hydrocarbon backbone and those that have sites in the backbone that are hydrolytically sensitive. Ester, anhydride, amide, or urethane linkages in the backbone usually serve this function. 

Hydrolases such as the digestive enzymes amylase and lactase catalyse hydrolysis of glycosides, esters, anhydrides and amides. 

Unstable compounds under the screening conditions (esters, anhydrides, thiols, heteroatom-heteroatom acyclic single bonds). 

Only scare data is available in the literature on the application of rhenium containing mono- or bimetallic catalysts in the hydrogenolysis of esters to alcohols. Decades ago Broadbent and co-workers studied the hydrogenation of organic carbonyl compounds (aldehydes, ketones, esters, anhydrides, acids,... 

In each nucleotide monomer of DNA or RNA molecules, a phosphate group is attached to the C-5 hydroxyl of each sugar residue in an ester (anhydride) linkage. These phosphate groups in turn are linked in diester bonds to neighboring sugar groups of adjacent nucleotides... 

Carbonyldiimidazole has been used for the preparation of such compounds as esters, anhydrides, amides, peptides, ketones, ethers, and isocyanates.2 The present procedure provides a convenient method for its preparation in good yield. 

Acyl chlorides are converted in good yield into symmetrical carboxylic acid anhydrides upon treatment with dilute aqueous sodium hydroxide at -I0°C in the presence of a tetra- -butylammonium salt [76, 77]. Yields are considerably lower when Aliquat is used. In a similar manner, chloroformates and ethyl oxalyl chloride are converted into carbonic hemi-ester anhydrides. 

Starting from Trifluoroacetic Acid Derivatives Trifluoroacetic acid and its derivatives (e.g., esters, anhydride, fluoral, trifluoroethanol) are the major channel of the organic fluorine industry. They are relatively inexpensive and, compared to halons, they do not exhibit major environmental problems. They are the main source for the synthesis of trifluoromethylated compounds. 

Two further properties which must be intimately related with the problems of the tetrahedral intermediate are the solvent isotope effect and the entropy of activation for the hydrolysis of RCOX. Table 2 lists the values of entropies of activation for the neutral hydrolyses of esters, anhydrides, and acid chlorides. Values of —30 to — 40 eu are common to the hydrolyses of esters and anhydrides, but for acid halides the value is down to---10 eu. The only slight... 

When an acyl group replaces the hydrogen of alcohols, carboxylic acids, hydrogen halides, ammonia or amines, we have the acyl compounds known as esters, anhydrides, halides, and amides, respectively. 

Structures 24 are conveniently thought of as derivatives of carboxylic acids, and include acids, esters, anhydrides, acyl halides, and amides. These structures (and others less commonly encountered) can be readily interconverted, either directly or indirectly the number of different reactions is therefore large.109 Because these processes occupy an important place in organic chemistry and because carboxylic acid derivatives are of central importance in biochemical systems and therefore of considerable interest in the study of enzyme action, they have been the subject of intensive investigation.110 We shall outline briefly the main features, and in order to give an idea of the kinds of mechanistic questions involved, we consider ester hydrolysis in somewhat greater detail. 

Nitriles Some amides, Sulphonic acids, Esters. Anhydrides. hydrocarbons. hydrazo and other... 

Except for lactam n-acyl derivatives, compounds such as esters, anhydrides and halogen anhydrides of carboxylic acids, which can activate lactam polymerization, can also be used as activators (promoters). 

Reactions of acid halides (acyl halides). Acyl halides are very reactive and easily converted to esters, anhydrides, amides, N-substituted amides, and carboxylic acids. In the following reactions, X represents any halide. 

The reaction is often followed by protonation of the oxygen. The C=0 group may be present in an aldehyde, ketone, ester, anhydride, acyl halide, amide, and so forth. Acid catalysts may be necessary with weak nucleophiles. The acid protonates the oxygen, making the carbon more positive and thus, more electrophilic. 

Dithiophosphonsaure-S-ester-O-Anhydride hzw. Trithiophosphonsaure-ester-Anhydride... 

Die trimeren Dithiophosphorsaure-O-ester-anhydride reagieren mit Alkoholen und Phenolen zu Dithiophosphorsaure-0,0-diestern247 ... 

Methan- -methylcster-Phosphorsaure-dimethyl-ester-Anhydrid... 

Ethan- -O-ethylester-Essigsaure-Anhydrid E2, 484 Ethan- -O-ethylester-Elhanphosphonsaure-ethylester-O-Anhydrid E2, 484 Ethan- -O-ethylester-Se-methylester E2, 485 Ethan- -O-ethylester-O-trimethylsilylester E2, 485 -O-ester-Anhydride E2, 484 Methan- -dibromid E2, 92, 484 Methan- -dichlorid XII/1, 602 Methan- -0,O-diester XII/1, 603 2-Methyl-propan- -O,O-bis-[2-methyl-pr0pylester] aus Bis-[2-methyl-propyloxy]-(2-methyl-propy])-phosphan mit Selen XII/1, 603 Natrium-ethan- -O-ethylester E2, 485 Propen-3- -dibutylester XII/1, 603... 

S-ester-Anhydrid E2, 344 -O-ester-O-Anhydrid E2, 437 -O-ester-O-N-ester E2, 448 -O-ester-hydrazid E2, 468 -O-ester-isothiocyanat E2, 467 -O-estcr-sulfonamid E2, 468 Ethan- (Dinatrium-Salz)... 

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