Infrared spectroscopy anhydrides

The first anhydride plant in actual operation using methyl acetate carbonylation was at Kingsport, Tennessee (41). A general description has been given (42) indicating that about 900 tons of coal are processed daily in Texaco gasifiers. Carbon monoxide is used to make 227,000 t/yr of anhydride from 177,000 t/yr of methyl acetate 166,000 t/yr of methanol is generated. Infrared spectroscopy has been used to foUow the apparent reaction mechanism (43). 

Finally, the techniques of nmr, infrared spectroscopy, and thin-layer chromatography also can be used to assay maleic anhydride (172). The individual anhydrides may be analyzed by gas chromatography (173,174). The isomeric acids can be determined by polarography (175), thermal analysis (176), paper and thin-layer chromatographies (177), and nonaqueous titrations with an alkaU (178). Maleic and fumaric acids may be separated by both gel filtration (179) and ion-exchange techniques (180). 

Infrared radiation, electromagnetic spectrum and, 419, 422 energy of. 422 frequencies of, 422 wavelengths of, 422 Infrared spectroscopy, 422-431 acid anhydrides, 822-823 acid chlorides, 822-823 alcohols. 428, 632-633 aldehydes, 428. 730-731 alkanes, 426-427 alkenes, 427 alkynes, 427 amides. 822-823 amines, 428, 952 ammonium salts, 952-953 aromatic compound, 427-428, 534 bond stretching in, 422... 

In particular, we were concerned that anhydrides could react with drugs containing active groups such as amines. Infrared spectroscopy... 

FIGURE 26 Fourier transform infrared spectroscopy of polymer samples prepared at either 130, 145, or 160°C with or without cyclo-benzaprine hydrochloride (CBP). Polymer prepared from 3,9-bis-(ethylidene-2,4,8,10-tetraoxaspiro[5,5)undecane) and a 25 75 mole ratio of trans-cyclohexane dimethanol and 1,6-hexanediol and contained 3 wt% phthalic anhydride and 7.5 wt% cyclobenzaprine hydrochloride (CBP). 

Synthesis. Functionalized monomers (and oligomers) of sebacic acid (SA-Me2) and 1,6 -bis(/ -carboxyphenoxy)hexane (CPH-Me2) were synthesized and subsequently photopolymerized as illustrated in Figure 1. First, the dicarboxylic acid was converted to an anhydride by heating at reflux in methacrylic anhydride for several hours. The dimethacrylated anhydride monomer was subsequently isolated and purified by dissolving in methylene chloride and precipitation with hexane. Infrared spectroscopy (IR), nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis results indicated that both acid groups were converted to the anhydride, and the double bond of the methacrylate group was clearly evident. 

Y. Chen, G. Zhou, N. Brown, T. Wang and Z. Ge, Study of lactol activation hy trifluoroacetic anhydride via in situ Eourier transform infrared spectroscopy. Anal. Chim. Acta, 497(1-2), 155-164 (2003). 

In films cured initially at 175°C, determination by infrared spectroscopy of the concentration of anhydride groups indicated that all potential cross-linking groups had reacted. 

In order to optimize the structure and properties of composites, a knowledge of the polymerization kinetics and mechanism are required. Various approaches have been taken to a determination of the kinetics of the polymerization including infrared spectroscopy 30,31). Although the various epoxide/anhydride/amine systems are... 

The isourea protocol was carried out in a 9 1 dichloromethane/N,N-dimethylf-ormamide (DCM/DMF) solvent mixture in sealed vessels, whereas the anhydride reactions were carried out in 1 -methyl-2-pyrrolidinone (NMP) under atmospheric pressure. In all experiments, the loading was estimated by on-bead Fourier transform infrared spectroscopy (FTIR) analysis and determined by cleavage from the PS Wang resin with 50% TFA in DCM. 

The formation of block copolymers from styrene-maleic anhydride and acrylic monomers was also indicated by pyrolytic gas chromatography and infrared spectroscopy. A comparison of the pyrograms of the block copolymers in Figure 7 shows peaks comparable with those obtained when mixtures of the acrylate polymers and poly(styrene-co-maleic anhydride) were pyrolyzed. A characteristic infrared spectrum was observed for the product obtained when macroradicals were added to a solution of methyl methacrylate in benzene. The characteristic bands for methyl methacrylate (MM) are noted on this spectogram in Figure 8. 

Macroradicals obtained by the heterogeneous copolymerization of styrene and maleic anhydride in poor solvents such as benzene were used to initiate further polymerization of selected monomers. This technique was used to produce higher molecular weight alternating copolymers of styrene and maleic anhydride and block copolymers. Evidence for the block copolymers was based op molecular weight increase, solubility, differential thermal analysis, pyrolytic gas chromatography, and infrared spectroscopy. 

Chen, Y. Zhou, G.X. Brown, N. etal., Study of lactol activation by trifluoroacetic anhydride via in situ Fourier transform infrared spectroscopy Anal. Chim. Acta 2003, 497, 155-164. 

Fig. 8.5 Hydrolysis of acetic anhydride investigated separately at Tr = 25°C (a) by calorimetry and (b) by infrared spectroscopy. Graph (a) shows measured and simulated reaction power graph (b) shows measured and simulated concentration-time curves of acetic anhydride. The simulated curve is from the kinetic parameters obtained from the calorimetric measurements, and is compared with the one determined by the IR measurements at 1139 cm-1. Reprinted in modified form with permission [18],...

The energy levels of the starting materials, the transition state, and the intermediate are all lower in the anhydride reaction than in the acid chloride reaction. So which goes faster We know the answer—acid chlorides are more reactive than anhydrides towards nucleophiles. The reason is that the stability of the starting materials is determined by the interaction between the carbonyl group and the substituent attached directly to it. This is a big effect as we know from infrared spectroscopy. 

A variety of other carbon-o gen groups have been suggested, including lactones, anhydrides, peroxides, ethers, and esters (14-18). These surfaces oxides have been studied by functional group reactions (18), titration, and infrared spectroscopy (15,... 

Infrared spectroscopy is a valuable tool for the structural analysis of acid derivatives. Ajrid chlorides, anhydrides, esters, amides, and nitriles all show characteristic infrared absorptions that can be used to identify these functional groups in unknowns. 

Hydrolysis of styrene-methacrylic anhydride copolymers. One gram samples of the copolymers were suspended in distilled water (150 ml.) and the mixtures were refluxed, with stirring, until solutions were obtained that were stable at room temperature. Copolymers with high styrene contents hydrolyzed slowly and required 108 hr. reaction times. These polymers formed soap-like solutions when completely hydrolyzed. The hydrolyzed polymers were isolated by freeze-drying and were examined by infrared spectroscopy to establish the completeness of hydrolysis. 

The use of acetic anhydride as the solvent facilitates432 intermolecu-lar iodide displacements at C-5 of 156. Acylation of the heterocyclic base occurred at N-l (as indicated by infrared spectroscopy) during the reaction, and this inhibited occurrence of intramolecular displacement. The electron-withdrawing effect of the acyl group presumably diminishes the nucleophilicity at N-3. N-Formyl-2, 3 -0-iso-propylidene-5 -0-p-tolylsulfonyladenosine also reacts intermolecu-larly with lithium chloride or sodium azide in methyl sulfoxide to give 5 -chloro and 5 -azido derivatives.432... 

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