Ester infrared spectroscopy

The role of specific interactions in the plasticization of PVC has been proposed from work on specific interactions of esters in solvents (eg, hydrogenated chlorocarbons) (13), work on blends of polyesters with PVC (14—19), and work on plasticized PVC itself (20—23). Modes of iateraction between the carbonyl functionaHty of the plasticizer ester or polyester were proposed, mostly on the basis of results from Fourier transform infrared spectroscopy (ftir). Shifts in the absorption frequency of the carbonyl group of the plasticizer ester to lower wave number, indicative of a reduction in polarity (ie, some iateraction between this functionaHty and the polymer) have been reported (20—22). Work performed with dibutyl phthalate (22) suggests an optimum concentration at which such iateractions are maximized. Spectral shifts are in the range 3—8 cm . Similar shifts have also been reported in blends of PVC with polyesters (14—20), again showing a concentration dependence of the shift to lower wave number of the ester carbonyl absorption frequency. 

Infrared Spectroscopy (ir). Infrared curves are used to identify the chemical functionality of waxes. Petroleum waxes with only hydrocarbon functionality show slight differences based on crystallinity, while vegetable and insect waxes contain hydrocarbons, carboxyflc acids, alcohols, and esters. The ir curves are typically used in combination with other analytical methods such as dsc or gc/gpc to characterize waxes. 

The acetyl content of cellulose acetate may be calculated by difference from the hydroxyl content, which is usually determined by carbanilation of the ester hydroxy groups in pyridine solvent with phenyl isocyanate [103-71-9J, followed by measurement of uv absorption of the combined carbanilate. Methods for determining cellulose ester hydroxyl content by near-infrared spectroscopy (111) and acid content by nmr spectroscopy (112) and pyrolysis gas chromatography (113) have been reported. 

Esters are usually readily identified by their spectroscopic properties (70). Among these, infrared spectroscopy (ir) is especially useful for identifying the carbonyl of the ester group that has characteristic absorption bands. The C=0 absorption is very strong in the ir at 1750-1735 cm in addition,... 

Confirmation of the linear arrangement came by physical techniques, especially electron diffraction and infrared spectroscopy. Later the nonequivalence of the nitrogen atoms in diazoaeetic ester was shown by means of labeling. ... 

Infrared spectroscopy is a major tool for polymer and rubber identification [11,12]. Infrared analysis usually suffices for identification of the plastic material provided absence of complications by interferences from heavy loadings of additives, such as pigments or fillers. As additives can impede the unambiguous assignment of a plastic, it is frequently necessary to separate the plastic from the additives. For example, heavily plasticised PVC may contain up to 60% of a plasticiser, which needs to be removed prior to attempted identification of the polymer. Also an ester plasticiser contained in a nitrile rubber may obscure identification of the polymer. Because typical rubber compounds only contain some 50% polymer direct FUR analysis rarely provides a definitive answer. It is usually necessary first... 

A series of reactions with gases have been selected for the rapid quantification of many of the major products from the oxidation of polyolefins. Infrared spectroscopy is used to measure absorptions after gas treatments. The gases used and the groups quantified include phosgene to convert alcohols and hydroperoxides to chloroformates, diazomethane to convert acids and peracids to their respective methyl esters, sulfur tetrafluoride to convert acids to acid fluorides and nitric oxide to convert alcohols and hydroperoxides to nitrites and nitrates respectively. 

In more complex enaminocarbonyl systems, the dominant form of the cation depends to some extent upon the nature of the system, e.g., whether or not part of the chain [244] is involved in a large structure, such as an alicyclic or aromatic ring, and whether or not the carbonyl group takes part in another competing conjugation, as in the ester group. Ultraviolet and infrared spectroscopy are... 

Analyses of the chloroform-soluble extracts of the subbituminous coal by Fourier transform infrared spectroscopy (FTIR) showed the presence of a sharp carbonyl absorption peak (1800-1650 cm ) in the extracts from the parent coal and in those obtained at yields less than about 10% wt dmmf. The peak, which is attributed to ketones and carboxylates, disappeared at higher conversions (16). Whitehurst and co-workers (12) established that carbonyl- containing compounds, such as esters and carboxylates, can cleave under thermal treatment to produce CO, CO2 and phenols. They concluded that the evolution of these gases during coal liquefaction could originate from the decomposition of similar oxygen functionalities in the coal. 

Selected entries from Methods in Enzymology [vol, page(s)] Application in fluorescence, 240, 734, 736, 757 convolution, 240, 490-491 in NMR [discrete transform, 239, 319-322 inverse transform, 239, 208, 259 multinuclear multidimensional NMR, 239, 71-73 shift theorem, 239, 210 time-domain shape functions, 239, 208-209] FT infrared spectroscopy [iron-coordinated CO, in difference spectrum of photolyzed carbonmonoxymyo-globin, 232, 186-187 for fatty acyl ester determination in small cell samples, 233, 311-313 myoglobin conformational substrates, 232, 186-187]. 

Applications in infrared spectroscopy A and B bands, iron-coordinated CO, 232, 186-187 application to allosteric mechanisms, 249, 566 bacteriorhodopsin, 246, 9, 380-381 caged compounds, 246, 6, 520-521 DNA [base pair formation, 246, 506 conformation, 246, 506-507 denaturation thermodynamics, 246, 506 ligand interactions, 246, 6, 507 sample requirements, 246, 506] fatty acyl ester determination in small cell samples, 233,... 

STD-286B (1 Dec 1967), Method 601.1.1, "Titanous Chloride (0.2N Standard Solution) 20) Frank pristera , 1 Expiosives in Vol 12 of Encyclopedia of Industrial Chemical Analysis, Wiley, NY (1971), pp443—45 (Nitroglycerin and Dynamites, Analysis) 445 (PETN) 445 fit 451 (Ethyleneglycol Nitrates) - 451 (Other organic nitrate esters) 451 (Ammonium Nitrate) 452—60 (Identification of explosives by infrared spectroscopy) 460—62 (Analysis of unknown HE s) 461—67 (Nitrogen content determinations) 467—70 (Other methods for quality control) 470—71 (67 references on analytical procedures)... 

A polyvinyl acetate latex prepared by semi-continuous polymerization at 55° using a polymethacrylic acid-nonylphenol-poly-ethoxylate phosphate ester emulsifier and sodium persulfate-sodium formaldehyde sulfoxylate initiator (23). The latex was cleaned by ion exchange and serum replacement using both Nuclepore and Pellicon membranes, and the cleaned latex and serum fractions were analyzed by conductometric titration. In addition, the dried films were extracted with water and organic solvents, and the extracts were analyzed by infrared spectroscopy and thermo-gravimetric analysis. 

IR monitoring of oxidation process. Monitoring lubricants by infrared spectroscopy is a well established technique. The infrared spectra of oxidized (used) engine oil samples can be split into three parts (a) above 1900 cm 1, (b) 1900 to 1500 cm 1, and (c) below 1500 cm"1. The spectral changes in the region between 1900 to 1500 cm 1 in commercial automotive oils (SAE 10W/40, API service SE) operated in a Toyota 20R engine over a 8000 km period were evaluated (Coates and Setti, 1984). Major absorptions bands (1900 to 1500 cm 1) of the spectra are [cm 1] 1732 (oxidation, carbonyl esters), 1710 (oxidation, carbonyl ketones/acids), 1629 (nitrate esters), 1605 (carboxylates) of used oils. 

Ultraviolet and infrared spectroscopies were used to verify the symmetry of the ester complexes of Fig. 4. The transport efficiency was related to the relative degree of hydrophobieity of the amino acids with an ordering as shown in Eq. 8.37... 

Infrared spectroscopy can also be of diagnostic use for the identification of organophosphorus compounds and comprehensive data is available from several sources.18 Diagnostic absorptions include the P—H stretch, which typically occurs in the region 2460-2450 cm-1, the P=0 stretch at 1320-1200 cm-1 and the P=N at 1440-1120 cm-1. Other useful absorptions include the P—O—(C) stretch at 870-730 cm-1 and the P—O—P stretch at 800-650 cm-1 found in phosphate esters. 

Since the two esters I and II are not available commercially, they will be synthesized by a procedure that is basically that of Jeffeiy and Vogel. The starting materials for the syntheses are the free acids, cyclopropanecarboxylic acid and cyclohexanecarboxylic acid. Each is first converted to the acid chloride with thionyl chloride, and the acid chloride is then allowed to react with the appropriate alcohol to form the ester. Alternatively the acid chlorides can be obtained commercially from Aldrich Chemical Co., Inc., Milwaukee, Wisconsin, and the first part of the syntheses can be dropped. The purity of the two esters is checked by refractometry, infrared spectroscopy, and vapor-phase chromatography and the heats of combustion are determined with a bomb calorimeter. It is suggested that each student in the team synthesize and check the purity of one of the esters and that both work together on the calorimetric measurements. 

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. 

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