Infrared spectroscopy acid anhydrides

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... 

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. 

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. 

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. 

Infrared spectroscopy provides a convenient method for studying the deprotection kinetics of resist polymers. For example, the deprotection kinetics of some alicyclic polymer resist systems comprising (i) poly(methylpropyl bicyclo[2.2.1]-hept-5-ene-2-carboxylate-co-bicyclo[2.2.1]hept-5-ene-2-carboxylic acid) (trivial name poly(carbo-t-butoxynorbomene-co-norbornene carboxylic acid) [poly(CBN-co-NBCA)] (I) and (ii) poly(methylpropyl bicyclo[2.2.1]hept-5-ene-2-carboxylate-co-maleic anhydride) (trivial name poly(carbo-t-butoxynorbomene-co-maleic anhydride) [poly(CBN-aZr-MAH)] (11) and containing triphenylsulfonium... 

Among the analytical applications using near-infrared spectroscopy have been the following determinations water in hydrocarbons water in alcohols water in carboxylic acids alcohols in hydrocarbons alcohols in acids acids in hydrocarbons acids in anhydrides amines in hydrocarbons benzene in hydrocarbons and olefins in hydrocarbons. By differential techniques it is possible, for example, to lower the sensitivity limits (detectability) by another factor of 10 over the usual limits. The usual limit for water in alcohols ranges from 0.05 to 0.2 %. Examples of special interest to biochemists are the applications of Klotz and Frank (1965) of near-... 

Acid Halides and Anhydrides Acid halides and anhydrides are rarely isolated as unknown compounds but they are commonly used as reagents and intermediates, and PROBLEM-SOLVING infrared spectroscopy can confirm that an acid has becai converted to a pure acid chlo-... 

Infrared spectral analyses were carried out employing both classical infrared spectroscopy, IR, and Variable temperature Fourier Transform Infrared Spectroscopy, FT-IR. All of the products showed the presence of bands associated with both the phosphorus and acid-derived moieties. Further, the products showed the presence of one or two new bands within the 1060 to 1120 cm region attributed to the formation of the PO-O-CO anhydride moiety. 

Synthesis of block copolymers The A-B-A block copolymers were prepared by reacting the middle block with the N-carboxy anhydride of Y benzyl-L-glutamate, yethyl-L-gluta-mate, c-N-carbobenzyloxy-L-lysine, Y niethyl-L-glutamate, or Y-methyl-D,L-glutamate. The polymerization was carried out in the absence of moisture at room temperature in dioxane-methylene dichloride mixture at 3 % total concentration of amino acid-NCA and the middle block. The polymerization was followed by infrared spectroscopy. After the pol3nneri-zation was terminated, the copolymer was precipitated in methanol for purification and then dried in vacuo. 

Despite their Hmited structure determination capabilities, ultraviolet and infrared spectroscopy were determinant characterization techniques in the early days of boronic acid research [332]. Notable IR absorptions are the strong H-bonded OH stretch (3300-3200 cm ), and a very strong band attributed to B-O stretch (1380-1310 cm ). IRis particularly diagnostic of the presence of boronic anhydrides. Upon anhydride (boroxine) formation, the OH stretch disappears and a new strong absorption appears at 680-705 cm [68]. 

Amino groups have also been acetylated with acetic anhydride in dimethylacetamide. Diethylamine was added, and the excess amine was titrated potentiometrically. The sequence distribution of an aromatic polyamide terpolymer prepared under various reaction conditions was determined by nuclear magnetic resonance spectrometry. Infrared spectroscopy and mass spectrometry have been used to estimate the degree of conversion of polyimides, ie. the extent of polyamic acid ring closure. 

Infrared spectroscopy can also be used to probe resonance in carboxylic acid derivatives. The dipolar resonance structure weakens the C=0 bond and causes a corresponding decrease in the carbonyl stretching frequency (Table 20-2). The IR data for carboxylic acids reported in Section 19-3 refer to the common dimeric form, in which hydrogen bonding reduces the stretching frequencies of both the 0-H and C=0 bonds to about 3000 and 1700 cm respectively. A special technique—vapor deposition at very low temperature—allows the IR spectra of carboxylic acid monomers to be measured, for direct comparison with the spectra of carboxylic acid derivatives. Monomeric acetic acid displays vc=o at 1780 cm similar to the value for carboxylic anhydrides, higher than that for esters, and lower than that of halides, consistent with the degree of resonance delocalization in carboxylic acids. 

Infrared IR spectroscopy is quite useful in identifying carboxylic acid derivatives The, carbonyl stretching vibration is very strong and its position is sensitive to the nature of IKT the carbonyl group In general electron donation from the substituent decreases the double bond character of the bond between carbon and oxygen and decreases the stretch mg frequency Two distinct absorptions are observed for the symmetric and antisym metric stretching vibrations of the anhydride function... 

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