Carboxyl Chemical structure

The term benzodiazepine refers to a specific chemical structure. Numerous benzodiazepine-receptor ligands exist which have different structures. These include the jS-carbolines (e.g. methyl-6,7-dimethoxy-4-ethyl-jS-carboline 3-carboxylate DMCM), triazolopyridazines (e.g. CL 218872), imidazopyridines (e.g. zolpidem), and pyrazolo-quinolinones (e.g. CGS 8216). In experimental animals these compounds produce... 

Fig. 6.2. Chemical structures of fluorescein and some commonly used derivatives. The carboxylic acid groups are used for forming conjugates with other molecules.

Several studies have dealt with the problem of discriminating between mastic and dammar, and three marker compounds of mastic have been identified moronic, masticadienonic and acetyl masticadienolic acids [42], The chemical structure of (iso)masticadienonic acid and 3-0-acetyl-3-epi(iso)masticadienonic acid is characterized by a side chain, as for dammarane molecules, but with a carboxylic acid end group (Table 12.1). Under pyrolysis conditions this side chain is susceptible to cleavage as demonstrated by the presence, among the pyrolysis products of mastic, of 2-methyl-pent-2,4-dienoic acid, that perfectly matches with the chemical structure of the side chain end. In addition 3-(9-acetyl-3-epi-(iso)masticadienolic acid also loses the acetyl group and, in contrast to masticadienonic acid, is not detected at all. 

Figure 1. Chemical structures of representative ligands investigated A) biotin, B) 2-(4 -hydroxyazobenzene) benzoic acid (HABA), C) charged (X=CH2) and neutral (X=NH2+) carboxylate MMP inhibitors, D) TIBO scaffold, E) sustiva, and F) hydroxyethylamine scaffold. The biotin derivatives," MMP inhibitors,19 TIBO analogs,21 and cathepsin D inhibitors22 derived from structures A), C), D), and F), respectively, have been published elsewhere.

The chemical structures of polymers will be changed by the evolution of small molecule products. The formation of C=C bonds in the polymer backbone by loss of H2 from hydrocarbon polymers, or HC1 from PVC, is well established and leads to colouration of the polymer, especially with increasing sequence lengths of conjugated unsaturation. Carboxylic acid groups are... 

In view of the inherent resistance of some surfactant metabolite isomers to complete mineralisation, efforts have to be mounted in order to obtain further insight into the reasons behind the persistence of these, such as the SPC and nonylphenol ethoxy carboxylates (NPECs). In order to achieve this, it would thus be indispensable to be able to fully elucidate the chemical structure of individual components, e.g. after isolation from environmental samples. Through the application of, for example, LC-ESI-MS-MS in combination with NMR analyses, this is now possible. 

Both HPLC and GC-MS were employed for the separation, identification and quantitation of the decomposition products of indigo and indigo carmine. The chemical structures of the dyes are shown in Fig. 3.73. Carboxylic acids were preconcentrated before HPLC analysis either by ion-exchange SPE or by solid-phase microextraction. HPLC measurements were performed in a Sarasep column (300 X 7.8 mm i.d.) using 5 mM H2S04 at a flow rate of 0.7 ml/min. Analytes were detected at 215 nm. The main intermediates formed during the photocatalytic decomposition are compiled in Table 3.26. The results demonstrated that... 

HPMA [36] and a vinyl metal-chelating monomer A-(A/, A/ -dicarboxy-methylaminopropyl)methacrylamide synthesized [35]. Chemical structures of HPMA and DAMA are given in Figure 4. Poly(HPMA-co-DAMA) was prepared by free radical copolymerization in methanol with AIBN as initiator. Molecular weight distribution was determined by size exclusion chromatography and content of side-chain carboxylic group by acid-base titration. 

The DuPont Nafion materials, both sulfonate and carboxylate varieties, are not entirely unique, as similar perfluorinated ionomers have been developed by others such as the Asahi Chemical Company (commercial name Aciplex) and the Asahi Glass Company (commercial name Flemion). The comonomer chemical structures of and further information on these materials are given in the recent review article by Doyle and Rajendvan. Now commercially unavailable, but once considered a viable alternative, the Dow Chemical Company developed a somewhat similar perfluorinated ionomer that resembled the sulfonate form of Nafion except that the side chain of the former is shorter and contains one ether oxygen, rather than two ether oxygens, that is, —O—... 

The sodinm salt of benzoic acid, sodinm benzoate, is a very commonly employed preservative. Let s pause here for a moment to re-emphasize an important point biological activity is a sensitive fnnction of chemical structure. Benzene, the parent molecule of benzoic acid, is a serions toxin in contrast, the sodium salt of benzoic acid is sufficiently safe to be added, in modest amounts, to a great many foodstnffs. The addition of the carboxyl gronp to benzene has created a far safer molecnle. 

Here we have another simple chemical transformation, the oxidation of the aldehyde group in retinal to the carboxyl group of retinoic acid. Although the chemical change is simple, the physiology is profoundly different. Retinoic acid has nothing to do with vision but a lot to do with development and differentiation. Here we have yet another example of the sensitive interdependence of chemical structure and biological function. 

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