Carboxylic acid band

The heat-treated materials are very reactive and are readily reoxidized in the presence of air. For example, the carboxylic acid band at 1725 cm 1 reappears when the sample heated to 600°C is milled in air instead of nitrogen (Figure 9). As expected from the above discusssions, the presence of these new surface species also enhances the absorptions at 1595 and 1245 cm 1. Interestingly, the air and nitrogen milling conditions have different effects on the magnitudes of the 1135 an 1340 cm 1 impurity bands of this carbon black. 

FT-IR spectra (9) of pectin/starch/glycerol (P/S/G) films were taken to provide information concerning the microstructure around ester and carboxylic acid side chains in the backbone of pectin. Pectin, unlike starch and glycerol, exhibits infrared absorption bands in the regions near 1610 and 1740 cm For pectin dissolved in D2O, absorption bands occur at about 1730, 1740, and 1607 cm. These arise from the carboxylic acid C=0 stretching band, the methyl ester C=0 stretching band, and iht antisynunetric COO stretching band, respectively. The carboxylic acid band overlaps the ester band sufficiently that these appear as one broad band (22). 

FTIR (wavenumber-assignment) cm V- imide absorption bands C=0 - 1780 and 725, C-N - 1380 carboxylic acid band of polyamic acid -1700 ... 

Characteristic carboxyl acid peak appears at 1730 cm with two other distinct bands at 1650 and 1550 cm located in the zone related to the (-CONH-), corresponding respectively to the (C=0) stretching band and to the (-NH) bending vibration band [101]. Indeed, as already reported by several authors [18, 102-103], the carboxylic acid band is well separated from the amide group (-CONH-) bands at 1650 and 1550 cm. The FTIR analysis clearly shows that an amide bond has been formed during the grafting reaction and a correlation between degrees of conversion and the intensity of characteristic peaks is indicated. 

Figure 5. Raman analysis of imide aromatic band (1612 cm ) and carboxylic acid band (1601 cm ) for SP-1 at different load, (a) wavenumber position, (b) relative intmsity...

Band 3, 3-93y. (2548 cm. ). This absorption is characteristic of carboxylic acids and is due to the 0—H stretching absorption in the reson-ance-stabUised dimer. (Carboxylic acids generally exist as dimers in the solid state and in all but very dilute solutions.)... 

Band 4, 5-9411 (1683 cm. ). Aryl carboxylic acid C=0 stretching vibration (Table IV). 

Carboxylic acids 3300-2500 (w-m) 995-915 (s) Broad Broad diffuse band... 

As discussed earlier in Section lOC.l, ultraviolet, visible and infrared absorption bands result from the absorption of electromagnetic radiation by specific valence electrons or bonds. The energy at which the absorption occurs, as well as the intensity of the absorption, is determined by the chemical environment of the absorbing moiety. Eor example, benzene has several ultraviolet absorption bands due to 7t —> 71 transitions. The position and intensity of two of these bands, 203.5 nm (8 = 7400) and 254 nm (8 = 204), are very sensitive to substitution. Eor benzoic acid, in which a carboxylic acid group replaces one of the aromatic hydrogens, the... 

The chemical reactions of this compound were recently reconsidered, and both structures 64 and 65 were rejected in favor of the zwit-terion formulation 66, which is supported by the presence of a band at S.lfx (3226 cm ) in the infrared spectrum and is merely an alternative canonical form of 64. On the other hand, the ultraviolet spectrum of 4-hydroxypyrrole-2-carboxylic acid (67) resembles that of its ethyl ether, possibly indicating that the 2-acid exists in the hydroxy form. -... 

Broadly speaking, in the study of AB cements derived from poly-carboxylic acids, the band of interest falls in the region 1550-1620 cm (Mehrota Bohra, 1983 Bellamy, 1975). This band is the asymmetric stretch of the carboxylate group and its exact position depends on both the nature of the bonding involved (i.e. whether purely ionic or partially covalent), and the nature of any chelation by the carboxylate group (Bellamy, 1975). 

Band 8, 7-lOy. 1408 cm. ). This is a characteristic carboxylic acid absorption band and it arises from a C—O vibration coupled with an... 

Based on a study of the reaction of diethylstannyl dicaprylate with some carboxylic acids (oleic, caprylic, caproic add, etc.) it was suggested that oleic acid tends to displace caprylic acid from the inner sphere of a carboxylate-type complex forming a sufficiently stable complex with tin. The spectrum of the initial diethylstannyl dicaprylate revealed a band at 1600 cm-1 which is intermediate between 1570 and 1720 cm-1. The latter bands are associated with vibrations of bonds... 

The tetrazinc [Zn4(/r4-0)(/i-C02CR)6] can be prepared by a variety of methods with short straight chain carboxylic acids and this structural type identified by characteristic IR bands. The formation process and influence of water were monitored by IR spectroscopy and a mechanism of formation and decomposition proposed.375 Further evidence for the validity of the mechanism,... 

The band at 1721 cm-1 may be due to the C = 0 stretching vibration of a carboxylic acid or ester. This band is observed in pure formic acid and in pure methyl formate at 1730 cm -1 [70]. The slight shift to lower frequency can be due to interaction with water. 

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