Carboxylic acids, functional derivatives compounds

The next several chapters deal with the chemistry of various oxygen-containing functional groups. The interplay of these important classes of compounds—alcohols, ethers, aldehydes, ketones, carboxylic acids, and derivatives of carboxylic acids— is fundfflnental to organic chemistry and biochemistry. 

E. Jacobson in 1882 fused phthalic anhydride with quinoline bases obtained from coal tar, which also contained quinaldine (136). He thus received quinophthalone (137). Quinophthalone derivatives bearing sulfonic or carboxylic acid functions represent suitable anionic dyes. Derivatives carrying basic side chains containing quarternary nitrogen, on the other hand, provide cationic dyes. The compounds are used especially as disperse dyes [1]. 

Carbon Disulfide under Sulfur Compounds Carbon Monoxide under Carbon Compounds Carbon Tetrachloride under Saturated Alkyl Halides Carbon Tetrafluoride under Saturated Alkyl Halides Carboxylic Acids Carboxylic Acids and Derivatives Carboxylic Acids with Other Functional Groups Cesium... 

The taurine residue can also be found as an amide derivative of the 26-carboxylic acid function in the 3p,5a,6p,15a-polyhydroxylated steroids 328 and 329, which were obtained from the starfish Myxoderma platyacanthum [245]. The structures of both compounds were determined from spectral data and chemical correlations. The bile of the sunfish Mola mola has been shown to contain a new bile acid conjugated with taurine (330) together with sodium taurocholate. Compound 330 was identified as sodium 2-[3a,7a, 11 a-trihydroxy-24-oxo-5P-cholan-24-yl]amino]ethane-sulfonate on the basis of its physicochemical data and chemical transformations [246]. 

Closely related to these compounds are the carolisterols A-C (331-333), which were isolated from deep-water starfish Styracaster caroli [247]. Carolisterols A-C are characterized by a polyhydroxycholanic acid moiety in which the 24-carboxylic acid function is found as an amide derivative of D-cysteinolic acid. Z)-cysteinolic acid has been found in fish, alga, and other marine organisms [248]. 

C-Terminal carboxylic acid function. Compounds containing a free C-terminal carboxylic acid function were found to have a much reduced inhibitory potency when compared with their C-terminal amide derivatives [48] (see Table 6.2). 

The importance of proline as the C-terminal amino acid in ACE inhibitors is best seen, if this building block is removed from enalaprUate that leads to a complete loss of activity. If the terminal carboxylic acid function is converted into the corresponding amide, or if proline is replaced by phenylalanine, this results in relatively poor affinity as well. However, good activity is found with bicyclic proline derivatives, which are optimised for their interactions in the S2-pocket (Fig. 5.15). [14,15] Many of the active compounds following on from enalapril possess this structural motif, e.g. ramiprilate (Hoechst) and tran-dolaprUate (Roussel) (Fig. 5.16). Like the majority of ACE inhibitors approved up to 2003, these compounds are administered as pro-drugs (ethyl esters). 

Studies within the Page group geared toward the synthesis of (f )-(-)-2,6-dimethylheptanoic acid [129], a simple natural produet derived from citronellal, have proved effective. This species contains a carboxylic acid function substituted at the a-carbon atom, a feature common to many analgesic compounds. This synthesis promises the first application of DiTOX as a chiral building block in organic synthesis... 

The structures of these compounds have numerous conjugated double-bonds and cyclic end groups thus, carotenoids present a variety of stereoisomers with different chemical and physical proprieties [5]. Carotenoids can be divided in two groups carotenes, constituted by polyunsaturated hydrocarbons C40 (Fig. 135.1), and xanthophylls their oxygenated derivatives and main contain epoxy, carbonyl, hydroxy, methoxy, or carboxylic acid functional groups (Fig. 135.2). 

Protection and Deprotection.— The carboxylic acid function can be protected by formation of the derivatives (50) using commercially available 1,1,1-tris(hydroxymethyl)ethane. Such compounds are best formed from a nitrile... 

Capillary GC-MS is an extremely powerful approach, combining the high separation efficiency of the capillary GC column with the identification power of the MS in electron-ionization mode. However the applicability range of GC is limited to relatively volatile compounds. In order to widen the applicability range, precolumn analyte derivatization strategies are often applied to enhance the volatility of the analytes. Methylation, silylation and acetylation reactions are most often applied for the analysis of compounds with amine, (poly-) hydroxy and/or carboxylic acid functional groups. Furthermore, derivatization to pentafluorobenzyl derivatives is applied to enhance the sensitivity of analytes in electron-capture negative-ion chemical ionization. 

Salts and esters of carboxylic acids and related compounds are named by placing the name of the metal or the esterifying group in front of the name of the acid anion, separated by a space. Joint occurrence of both functions is indicated accordingly. Acid salts and esters are named analogously. Complex cases can also be named more descriptively ... salt or. .. ester of. .. acid. (Similar provisions are valid for other acid derivatives such as amides and nitriles.)... 

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