Carboxylic acid spectroscopy

As Smith (300) has shown by infrared spectroscopy, carboxylic acids are adsorbed either by hydrogen bonding of the carboxyl group or by proton transfer to the surface. Carboxylate absorptions were observed in the spectra. Very likely O " or OH ions acted as proton acceptors although no OH absorption bands could be detected after carboxylic acid adsorption. The isoelectric point of pure anatase is near pH 6.6 (305). 

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... 

Claisen condensation, 6, 156 reactions, S, 92 IsothiazoIe-3-carboxyIic acids decarboxylation, 6, 156 Isothiazole-4-carboxylic acids decarboxylation, 6, 156 Isothiazole-5-carboxylic acids decarboxylation, S, 92 6, 156 IR spectroscopy, 6, 142 Isothiazole-3-diazonium borofluoride decomposition, 6, 158 IsothiazoIe-4-diazonium chloride, 3-methyl-reactions with thiourea, 6, 158 Isothiazole-5-diazonium chloride, 4-bromo-3-methyl-halogen exchange, 6, 163 Isothiazole-5-diazonium chloride, 3-methyl-reactions... 

There are many reports of the use of mass spectroscopy coupled to chromatography outlets for detection and identification of dmgs and metabolites. An example is compound 126 (99MI2, 99MI3). Carboxylic acids have been converted into hydrazides and hence into 3-substituted [l,2,4]triazolo... 

Carboxylic acid groups can be detected by both and A3C NMR spectroscopy. Carboxyl carbon atoms absorb in the range 165 to 185 8 in the l3C NMR spectrum, with aromatic and unsaturated acids near the upheld end of the range (—165 8) and saturated aliphatic acids near the downfield end (—185 8). Nitrile carbons absorb in the range 115 to 130 8. 

Acid anhydride, amides from, 807 eleclrostatic potential map of, 791 esters from, 807 from acid chlorides, 806 from carboxylic acids, 795 1R spectroscopy of, 822-823 naming, 786... 

Acid chloride—con l d esters from, 802-803 from carboxylic acids, 794-795 Grignard reaction of, 804-805 hydrolysis of, 802 IR spectroscopy of, 822-823 ketones from, 805 mechanism of formation from carboxylic acids, 795 naming, 786... 

Spectroscopy of Carboxylic Acids and Nitriles 770 Focus On. .. Vitamin C 772... 

Polyamides and Polyesters Step-Growth Polymers 818 21.10 Spectroscopy of Carboxylic Acid Derivatives 822... 

Trimethylsilyl l//-azepine-f-carboxylate (4), prepared in 71 % yield by treating methyl 17/-azepine-1 -carboxylate with iodotrimethylsilane in chloroform at 20°C, with methanol in pentane solution at — 78 °C undergoes slow hydrolysis to the bright-yellow 17/-azepine-l-carboxylic acid (5),9 which is also obtained, as the potassium salt, by the action of potassium /ert-butoxide on ethyl 17/-azepine-l-carboxylate.139 The acid is stable at —78°C for several days but in chloroform solution at 20 °C undergoes decarboxylation to 17/-azepine (6) accompanied by some decomposition. 17/-Azepine is stable for a few hours at — 78 C and has been characterized by 3H and l3CNMR spectroscopy. 

In his pioneering work, Sus (1944) assumed that the final product of photodediazoniation of 2,1-diazonaphthoquinone (10.75) is indene-l-carboxylic acid (10.79, not the 3-isomer 10.78). He came to this conclusion on the basis of some analogies (in addition to an elemental analysis). Cope et al. (1956) as well as Yates and Robb (1957) found that the infrared spectrum of the product was consistent with an a,P-unsaturated acid. Later, Melera et al. (1974) verified the structure 10.78 by H NMR spectroscopy. Friedrich and Taggart (1975) showed that the equilibrium between 10.78 and 10.79 at 233 K lies on the side of the latter, but 10.78 clearly predominates at or above 0°C. Ponomareva et al. (1980) showed that not only 2,1-, but also 1,2-diazo-naphthoquinone yields indene-3- and not -1-carboxylic acid. 

Fourier transform infrared (FTIR) spectroscopy (NaCl) shows no remaining carboxylic acid (1696 cm-1, carbonyl) but only ester groups (1736 cm 1, carbonyl) Mn(SEC) = 6530 Mn(1H NMR) = 1640 theory for third generation Mn = 2570.65 Polyesters of higher generation were synthesized according to this pseudo-one-step procedure and were analyzed by SEC, VPO, and 111 NMR.65... 

Many impurities are present in commercial caprolactam which pass into the liquid wastes from PCA manufacture from which caprolactam monomer may be recovered. Also, the products of die thermal degradation of PCA, dyes, lubricants, and other PCA fillers may be contained in the regenerated CL. Identification of die contaminants by IR spectroscopy has led to the detection of lower carboxylic acids, secondary amines, ketones, and esters. Aldehydes and hydroperoxides have been identified by polarography and thin-layer chromatography. 

The coordination of [Me2Sn(IV)f to captopril (cap) [(2S)-l-[(2S)-2-methyl-3-sulfanyl propanoyl]pyrrolidine-2-carboxylic acid] in aqueous solution was studied by means of pH-metric titration, electrospray mass spectrometry, H NMR, and Mossbauer spectroscopies in the 2-11 pH range. The results obtained proved that only monomeric complexes are formed in solution. In the acidic pH... 

The photo-Kolbe reaction is the decarboxylation of carboxylic acids at tow voltage under irradiation at semiconductor anodes (TiO ), that are partially doped with metals, e.g. platinum [343, 344]. On semiconductor powders the dominant product is a hydrocarbon by substitution of the carboxylate group for hydrogen (Eq. 41), whereas on an n-TiOj single crystal in the oxidation of acetic acid the formation of ethane besides methane could be observed [345, 346]. Dependent on the kind of semiconductor, the adsorbed metal, and the pH of the solution the extent of alkyl coupling versus reduction to the hydrocarbon can be controlled to some extent [346]. The intermediacy of alkyl radicals has been demonstrated by ESR-spectroscopy [347], that of the alkyl anion by deuterium incorporation [344]. With vicinal diacids the mono- or bisdecarboxylation can be controlled by the light flux [348]. Adipic acid yielded butane [349] with levulinic acid the products of decarboxylation, methyl ethyl-... 

To examine this peculiar behavior, we have converted the elastic compressibility modulus, per unit area, Y (Fig. 12a), to the modulus per chain, Y = F/10 F (Fig. 12b). The elastic compressibility modulus per chain is practically constant, 0.6 0.1 pN/chain, at high densities and jumps to another constant value, 4.4 0.7 pN/chain, when the density decreases below the critical value. The ionization degree, a, of the carboxylic acid determined by FTIR spectroscopy gradually decreases with increasing chain density due to the charge regulation mechanism (also plotted in Fig. 12b). This shows that a does not account for the abrupt change in the elastic compressibihty modulus. 

Kim et al. synthesized similar dendritic pseudorotaxanes as shown in Fig. 16 [58]. Reaction of triply-branched amine 42 with pseudorotaxane 43 incorporating CB[6] threaded on a string with a carboxylic acid terminus in DMF in the presence of EDC produces branched [4]pseudorotaxane 44, which is a G-1 dendritic pseudorotaxane. Coupling between 42 and pseudorotaxane dendritic wedge 45 under similar conditions yields G-2 dendritic pseudorotaxane 46, which contains 9 beads threaded on a dendritic framework ([lOjpseudorotax-ane). These dendritic pseudorotaxanes have been characterized by NMR spectroscopy, but further characterization remains to be done. 

Here we shall confine ourselves to the solvents benzene and 1,2-dichloroethane (class 8). Considering benzene, many investigators have demonstrated since the 1930s the feasibility of titrations in this solvent using both potentiometric and spectrophotometric methods, paying much attention to acid-base indicator reactions under the influence of primary, secondary and tertiary amines. Association of carboxylic acids in benzene was studied at a later stage, mainly on the basis of colligative properties, IR spectroscopy and solvent extraction. ... 

The heats of ionisation and neutralisation of amino and hydroxylic bis and tris phosphonic acids have been investigated.253 Calorimetry in combination with u.v. and n.m.r. spectroscopy uas used to study the adducts of fluoroalkyl carboxylic acids with diethyl phosphonate.254 The heats of formation of the t-butoxytriphenylphosphoranyl radical uas consistent with the phosphonium structure (92).255 There has been a thermal analysis of the adducts of phosphonic and phosphoric acids with... 

The kinetics of deuterium isotope exchange between diphenyl phosphine and t-butylthiol have been studied by H n.m.r. spectroscopy.274 A negative temperature coefficient was observed for the reaction of a perf1uoroalky1 phosphite with a fluorinated aldehyde.275 The kinetics for the reaction of alcohols with phosphoryl trichloride bore strong similarities to those of carboxylic acid derivatives.276 An interesting report desribed the solvolysis of ary 1 hydroxymethyl-phosphonates. It was shown that a phosphoryl group does not prevent carbocation formation on an immediately adjacent carbon atom.277... 

The first example of a stable geminal enediol derivative of a carboxylic acid, isolated as its platinum(II) complex, has been reported.324 Treatment of [Pt(OH2)2(en)]2+ with /V,/V-bis(phos-phonomethyl)aminoacetic acid yields zwitterionic [Pt(bpmaa)(en)] (bpmaaH = 7V,7V-bis(phosphono-methyl)aminoacetic add), which upon crystallization from water (pH 1) affords the corresponding enol tautomer (130), as determined by X-ray crystallography and IR spectroscopy. 

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,... 

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