Anhydrides isobutyric

Although TMCD is not commercially available, technology for its preparation from isobutyric acid or isobutyric anhydride has been reported [79-83], A process for separation of the individual cis- and trans-isomers of TMCD has also been reported [84], TMCD is usually prepared with an approximate 50/50 cis/trans ratio, and this is the usual equilibrium isomer ratio used for polyester preparation, although polyesters prepared from other isomer ratios and from the pure m-isomer have been reported [77, 78],... 

Figure 4. Infrared spectra of (A) isobutyric anhydride, (B) glutaric anyhdride, and (C) isotactic and (D) atactic poly(a,a-dimethylbenzyl methacrylate)s heated at 174° C under vacuum for 2 and 3 hr, respectively.

A new class of chiral 4-A,A-dialkylaminopyridine acyl-transfer catalysts has been developed that are capable of exploiting both van der Waals (jt) and H-bonding interactions to allow remote chiral information to control stereochemically the kinetic resolutions of secondary alcohols with moderate to excellent selectivity (S = 6-30). Catalysts derived from (.S )- , -diarylprolinol (89 Ar = Ph, 2-naphthyl) in combination with isobutyric anhydride were found to possess high activity and selectivity across a broad range of substrates 89... 

Later, the chiral bicyclic phosphine catalyst 5a was also used for kinetic resolution of allylic alcohols with isobutyric anhydride [8, 9]. The best results were obtained for trisubstituted allylic alcohols - selectivity factors ranged from 32 to 82 at -40 °C. 

Acetylacetanilide 2-Amino-2-thiazoline Isobutyric anhydride Sodium hydroxide... 

The same effect is found for toluene acylation over BEA zeolite with derivatives of isobutyric acid isobutyric anhydride presents a higher initial activity compared with isobutyric chloride.[6]... 

Sucrose Acetate Isobutyrate occurs as a clear, pale yellow, viscous liquid. It consists of a mixture of sucrose esters of acetic and isobutyric acid, with sucrose diacetate hexaisobu-tyrate being the predominant sucrose ester. It is produced through the controlled esterification of sucrose with acetic anhydride and isobutyric anhydride. It is very soluble in essential oils such as orange oil, soluble in ethanol and in ethyl acetate, and very slightly soluble in water. 

A suspension of 4-chloro-2-aminophenol (8.39 mmol) and 25 ml water was treated with 1.6 ml isobutyric anhydride, then stirred 30 minutes at 60°C, and cooled. A precipitate that formed was washed twice with water, dried, and the product isolated in 78% yield as a white solid. 

A completely different approach was pursued by Fuji and coworkers [14]. The enantiomeri-cally pure pyridine derivative 18 was prepared, the rationale being that the reduced steric hindrance in the proximity of the nitrogen nucleus should result in efficient catalytic turnover and that chiral recognition might be possible by remote asymmetric induction in a process similar to the induced fit mechanism in enzymes. When 18 was reacted with racemic 19b and isobutyric anhydride (l/ ,25)-19b was recovered with ee = 81% (71% conversion, 5 = 4.5,... 

Scheme 7). Interestingly, the optical purity of the recovered alcohol is dependent on the electron donating ability of the aromatic nuclei in the substrate, possibly indicating that n-n stacking plays a pivotal role in the enantiodifferentiat-ing event. It was also shown that the pyridinium ion derived from 18 and isobutyric anhydride adopts a closed conformation , in contrast to 18, in which the naphthyl moiety is situated over the pyridine ring, thus shielding the si face of the carbonyl group and supporting the induced fit concept.

Heating the imidazole ribonucleoside (656) with acetic anhydride and pyridine produced (657). Propionic anhydride reacted comparably (75JOC2920). The same ring system can be prepared by treating uric acid (658) with isobutyric anhydride. Cleavage and rearrangement... 

Catalysis of the synthesis of benzoic anhydride and the hydrolysis of benzoyl chloride, diphenyl phosphorochloridate (DPPC), and benzoic isobutyric anhydride in dichloromethane-water suspensions by water-insoluble silanes and siloxanes, 3- and 4-trimethylsilylpyridine 1-oxide (3b and 3c, respectively), 1,3-bis(l-oxypyridin-3-yl)-l,1,3,3-tetramethyldisiloxane (4), and poly[methyl(l-oxypyridin-3-yl)-siloxane] (5) was compared with catalysis in the same systems by water-soluble pyridine 1-oxide (3a) and poly(4-vinylpyridine 1-oxide) (6). All catalysts were effective for anhydride synthesis and promoted the disproportionation of benzoic isobutyric anhydride. Hydrolysis of benzoyl chloride gave benzoic anhydride in high yield ( 80%) for all catalysts except 3a, which gave mixtures of anhydride (52%) and benzoic acid (39%). The order of catalytic activity for DPPC hydrolysis was 5 > 4 > 3b > 3a > 3c > 6. The results suggest that hydrophobic binding between catalyst and lipophilic substrate plays an important role in these processes. 

Fife and Xin (35) found that, under PTC conditions, the reaction between benzoyl chloride and a mixture of 1.0 equivalent of sodium p-toluate and 1.0 equivalent of sodium isobutyrate in the presence of 0,1 equivalent of pyridine 1-oxide gave an anhydride product mixture that contained approximately twice as much benzoic p-toluic anhydride as benzoic isobutyric anhydride on a molar basis (equation 7). Therefore, the process must include an important component that selects for the more lipophilic p-toluate ion. The differential partitioning of the competing carboxylate ions at the di-chloromethane-water interface is a reasonable explanation for this observed selectivity, because product composition correlates with the Hansch (39) hydrophobicity parameters for competing carboxylate ions (40). 

Hydrolysis of Benzoic Isobutyric Anhydride. Reactions of mixed anhydrides can be complicated by disproportionation reactions (equation 10). The process may be operative in any investigation of anhydride hydrolysis, but it would go undetected in studies with symmetrical anhydrides or in studies that just monitor reaction rates by consumption of base. To obtain a more complete understanding of the catalytic behavior of 3, 4, 5, and 6 in transacylation reactions, the hydrolysis of benzoic isobutyric anhydride was investigated. 

NMR analysis was used to fully characterize product mixtures, because the chemical shifts of aliphatic protons are different for benzoic isobutyric anhydride and isobutyric anhydride, a possible disproportionation product (36). The results are given in Table IV. In all cases, disproportionation accompanied the hydrolysis of benzoic isobutyric anhydride in stirred suspensions of dichloromethane-0.5 M aqueous sodium bicarbonate. All catalysts behaved similarly, despite the major solubility differences of 3a and 6 versus 3b, 3c, and 5. For the hydrolysis of benzoic isobutyric anhydride, as with the other studies described in this report, 1-oxypyridinyl-substituted... 

Note Reactions were run and worked up as described in Table II, footnote. Product analysis was by integration of H-NMR signals for the methyl protons in the isobutyryl group of benzoic isobutyric anhydride (8 (CDCb) 1.30, d) and isobutyric anhydride (8 (CDCI3) 1.24, d). 

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