Carboxyhc acids, esters

Difluoroethanol is prepared by the mercuric oxide cataly2ed hydrolysis of 2-bromo-l,l-difluoroethane with carboxyHc acid esters and alkaH metal hydroxides ia water (27). Its chemical reactions are similar to those of most alcohols. It can be oxidi2ed to difluoroacetic acid [381-73-7] (28) it forms alkoxides with alkaH and alkaline-earth metals (29) with alkoxides of other alcohols it forms mixed ethers such as 2,2-difluoroethyl methyl ether [461-57-4], bp 47°C, or 2,2-difluoroethyl ethyl ether [82907-09-3], bp 66°C (29). 2,2-Difluoroethyl difluoromethyl ether [32778-16-8], made from the alcohol and chlorodifluoromethane ia aqueous base, has been iavestigated as an inhalation anesthetic (30,31) as have several ethers made by addition of the alcohol to various fluoroalkenes (32,33). Methacrylate esters of the alcohol are useful as a sheathing material for polymers ia optical appHcations (34). The alcohol has also been reported to be useful as a working fluid ia heat pumps (35). The alcohol is available ia research quantities for ca 6/g (1992). 

Table 3 gives the corresponding physical properties of some commercially important substituted pyridines having halogen, carboxyHc acid, ester, carboxamide, nitrile, carbiaol, aminomethyl, amino, thiol, and hydroxyl substituents. 

Carboxyhc acid ester, carbamate, organophosphate, and urea hydrolysis are important acid/base-catalyzed reactions. Typically, pesticides that are susceptible to chemical hydrolysis are also susceptible to biological hydrolysis the products of chemical vs biological hydrolysis are generally identical (see eqs. 8, 11, 13, and 14). Consequentiy, the two types of reactions can only be distinguished based on sterile controls or kinetic studies. As a general rule, carboxyhc acid esters, carbamates, and organophosphates are more susceptible to alkaline hydrolysis (24), whereas sulfonylureas are more susceptible to acid hydrolysis (25). 

This reaction can be extended to unsaturated nitriles, eg, acrylonitrile, which can give trihalostannyl-functional carboxyHc acids, esters, and amides by the proper choice of solvents and reaction conditions (156). 

Solvent Resistance. Poly(vinyl alcohol) is virtually unaffected by hydrocarbons, chlorinated hydrocarbons, carboxyhc acid esters, greases, and animal or vegetable oils. Resistance to organic solvents increases with increasing hydrolysis. This resistance has promoted the use of PVA in the manufacture of gloves for use when handling organic solvents (73). 

Solid Peroxygen Compounds. Hydrogen peroxide reacts with many compounds, such as borates, carbonates, pyrophosphates, sulfates, sihcates, and a variety of organic carboxyHc acids, esters, and anhydrides to give peroxy compounds or peroxyhydrates. A number of these compounds are stable sohds that hydrolyze readily to give hydrogen peroxide in solution. 

The resolving of a variety of a-substituted carboxyHc acid esters by a previously undescribed enzyme, Candida lipolytica esterase, has been reported (64). a-Methyl-a-amino (49) and a-methyl-a-hydrazino (48) esters, which function as inhibitors of acid decarboxylase enzymes, are obtained on a multigram scale in optically pure form. 

Table 3 Hsts only those carboxyHc acid esters whose 1990 U.S. production, sales quantity, value, and raw materials have been pubHshed (95). They are grouped on the basis of their principal use. For a complete Hst of the organic esters produced and sold in the United States and their manufacturers, the original pubHcation should be consulted. Uses of some specific esters are also given in Table 4.

Wong and co-workers have prepared various quaternary ct-nitro-ct-methyl carboxyhc acid esters by the palladium-catalyied allyhc alkyladon of ct-nitropropionate ester fEq 5 59 The products can be kmedcaUy resolved by using ct-chymotrypsin and are converted into opdciil acdve ct-methyl ct-amino acids Such amino acids are important due to the unique biological acdvity of these nonproteinogenic ct-amino acids... 

Classically, the acylzirconocene chlorides can be converted into aldehydes, carboxyhc acids, esters, and acyl halides. Recently, the usefulness of acylzirconocenes has been extended. In fact, these unmasked acyl anions directly add to aldehydes and imines affording a-hydroxy or a-amino ketones, respectively. The reaction of acylzirconocene chlorides with imines also proceeds under Bronsted acid-catalyzed conditions, even with aqneons acids. ... 

Five important classes of organic compounds containing carbonyl compounds are aldehydes, ketones, carboxyhc acids, esters, and amides. 

Common Uses Name an aldehyde, ketone, carboxyhc acid, ester, or amide used for each of the following purposes. 

Bp3-OEt2 followed hy DiisobutyUduminum Hydride is used for the 1,2-reduction of y-aimno-Q, -unsaturated esters to give unsaturated amino alcohols, which are chiral building blocks for a -amino acids. Q , -Unsaturated nitroalkenes can be reduced to hydroxylamines by Sodium Borohydride and BF3-OEt2 in THF extended reaction times result in the reduction of the hydroxylamines to alkylamines. Diphenylamine-borane is prepared from sodium borohydride, BF3-OEt2, and diphenylamine in THF at 0 °C. This solid is more stable in air than BF3-THF and is almost as reactive in the reduction of aldehydes, ketones, carboxyhc acids, esters, and anhydrides, as well as in the hydrob-oration of alkenes. 

The above mechanism is supported by the following evidence (i) the carbonyl carbon in the diazomethyl ketone becomes the carboxyl carbon in the resulting acid, as shown by studies (ii) the migrating group R migrates with retention of configuration and (iii) in the absence of water or alcohol, under favorable conditions the intermediate ketene may be isolated. The actual product of the reaction is thus the ketene, which reacts with water, alcohols, or amines to give carboxyhc acids, esters, or amides, respectively (Scheme 5.58). 

In another invention, the plasticizer functions as the sole solvent for the functionalized monomer during the emulsion polymerization and additionally functions as a plasticizer for the final polymer product. Various carboxyhc acid esters or phosphates can be selected for this application... 

The thermal degradation of copolymers of MOBH and CHSS, NPSS, or PhSS was studied by in-situ FT-IR spectroscopy. The spectral changes of the sample film were measured at a constant temperature. When the crosslinked P(MOBH-CHSS) film was baked at 120 X, the peaks at 1720 (carboxyhc acid ester) and 1178 cm (sulfonic acid ester) decreased and the peak at 1018 cm (sulfonic acid) increased. The carboxylic acid ester moiety due to MOBH unit and sulfonic acid ester unit due to CHSS decreased simultaneously. The increase of the peak at 1018 cm corresponded to the decrease of the peak at 1178 cm. When the crosslinked P(MOBH-NPSS) film was baked at 150 X, the peak at 1720 cm (carboxylic acid ester) decreased and then followed by the decrease of the peak at 1178 cm (sulfonic acid ester). The increase of the peak at 1018 cm (sulfonic acid) corresponded to the decrease of the peak at 1178 cm as shown in Figure 7. Furttiennore, no thermolysis of PhSS units in the crosslinked P(MOBH-PhSS) was observed when baked at 240 X. 

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