Carboxylic derivatives, properties

Oxidation of carbohydrates can be achieved by either chemical or biochemical processes [98, 99]. Owing to their cation sequestering properties, the resulting carboxylic derivatives find potential applications in the detergent industries [100, 101]. Although homogeneous catalysts are often used in oxidation processes, utilization of solid catalysts has proved to be a feasible alternative [102]. 

A most important property of any sequestering agent to be used in chelation therapy is oral activity. One of the few agents to show any oral efficacy as an iron removal drug is 2,3-dihydroxybenzoic acid u4). Therefore, the 2,3-dihydroxyterephthalate conjugates of spermine and spermidine have been synthesized 115) according to the general scheme outlined above. While the neutral catechol derivative is insoluble in water, the carboxylate derivative shows increased water solubility and lower toxicity. 

With carboxyl-derived functions such as esters and amides, the initial activity of the drug, lost in introducing the carboxyl group, is often regained. Amides, ureides, hydantoins and barbiturates share CNS-depressing properties and are frequently indispensable elements of sedative, tranquillizing and anticonvulsant drugs. Nitriles as substituents are often comparable to chlorine atoms, but sometimes more toxic. 

The effectiveness of the aza-annulation of cyclohexanone imines with various activated acrylic acid derivatives was the subject of an in-depth study.28 The efficiency of aza-annulation with respect to the properties of the inline substrate, carboxylate derivative, and acrylate substitution was investigated. When different methods for activation of acrylic acid were used in the aza-annulation of 59, acryloyl chloride produced very low mass recovery with significant amounts of the. V-acylated derivative 60 (eq. 15). In the presence of NEt3, 60 was essentially the only product formed. Attempts to convert 60 to either 61 or 62, through the use of Lewis acids, protic acids, and temperatures as high as 200 °C, were unsuccessful. Only photochemical methods have been used to effectively facilitate this conversion (60 — 61, R =CH2Ph, R2=R3=H hv, 61%).29... 

Pyridine is a tertiary amine its aqueous solution shows an alkaline reaction and precipitates the hydroxides of metals, some of which are soluble in an excess of the amine. Salts of pyridine like those of other amines form characteristic double salts with metallic halides. The ferrocyanide of pyridine and the addition-product of pyridine and mercuric chloride are difficultly soluble in water these compounds are used in the purification of the base. Pyridine is a very stable compound it can be heated with nitric acid or chromic acid without undergoing change but at 330° it is converted by a mixture of nitric acid and fuming sulphuric acid into nitropyridine, a colorless compound that melts at 41° and boils at 216°. At a high temperature pyridine is converted into a sulphonic acid by sulphuric acid. Chlorine and bromine form addition-products, e.g., C5H5N.CI2, at the ordinary temperature when these are heated to above 200°, substitution-products are formed. The hydroxyl derivative of pyridine is made by fusing the sulphonic acid with sodium hydroxide it resembles phenol in chemical properties. The three possible carboxyl derivatives of pyridine are known. The a-acid is called picolinic acid, the jS-acid nicotinic acid (664), and the 7-acid isonicotinic acid. 

Poly(phenylene oxides), synthesis and properties of carboxylated derivatives [97]. 

The chiroptical properties of optically active thiazoUdines derived from aldoses and natural mercapto aminoacids was studied [92]. PMR parameters for thiazoHdine-4(R)-carboxylate derivatives were obtained by computer-assisted analysis of their spectra. The polyacetoxy-alkyl side chains have planar zig-zag conformations. The configurations at C-2 in the di-astereoisomers were ascertained on the basis of the Jnh.ch coupling constants [93]. The conformation and stereochemistry of diastereomeric sulfoxides of methyl 3-acetyl-5,5-dimethyl-2-(D-galactopentaacetoxypentyl)-1,3-thiazolidine-4-carboxylate 1-oxides were performed by H- and C-NMR spectral analysis [94]. 

Piasecki, A. Ruchala, P. Synthesis, surface properties, and hydrolysis of chemodegradable anionic surfactants diasteromeric sodium carboxylates derived from 1,3-dioxane. J. Colloid Interface Sci. 2000, 226, 252-259. Galante, D.C. Hoy, R.C. Joseph, A.F. King, S.W. Smith, C.A. Wizda, C.M. Eur. Patent Appl., EP 0 742 178, 1996. 

Corrie JET, Munasinghe VRN, Retting W (2000) Synthesis and fluorescence properties of substituted 7-aminocoumarin-3-carboxylate derivatives. J Heterocycl Chem 37 1447-1455... 

Photophysical Properties of Enones and a,P-Unsaturated Carboxylic Derivatives... 

It should be noted that only representative substances are indicated in the above list. Substituted derivatives of the compounds in most classes may be encountered, e.g., nitrobenzoic acid in the aromatic carboxylic acids (p. 347). This acid will contain CH(0)N, but the salient properties are still those of a carboxylic acid, CH(0), Section 14, although the properties of an aromatic nitro-compound (e.g.y reduction to an amino-compound) will also be evident. 

The order of reactivity of carboxylic acid derivatives toward nucleophilic acyl sub stitution can be explained on the basis of the electron donating properties of sub stituent X The greater the electron donating powers of X the slower the rate... 

Maleic and fiimaric acids have physical properties that differ due to the cis and trans configurations about the double bond. Aqueous dissociation constants and solubiUties of the two acids show variations attributable to geometric isomer effects. X-ray diffraction results for maleic acid (16) reveal an intramolecular hydrogen bond that accounts for both the ease of removal of the first carboxyl proton and the smaller dissociation constant for maleic acid compared to fumaric acid. Maleic acid isomerizes to fumaric acid with a derived heat of isomerization of —22.7 kJ/mol (—5.43 kcal/mol) (10). The activation energy for the conversion of maleic to fumaric acid is 66.1 kJ/mol (15.8 kcal/mol) (24). 

Carbon Cha.in Backbone Polymers. These polymers may be represented by (4) and considered derivatives of polyethylene, where n is the degree of polymeriza tion and R is (an alkyl group or) a functional group hydrogen (polyethylene), methyl (polypropylene), carboxyl (poly(acryhc acid)), chlorine (poly(vinyl chloride)), phenyl (polystyrene) hydroxyl (poly(vinyl alcohol)), ester (poly(vinyl acetate)), nitrile (polyacrylonitrile), vinyl (polybutadiene), etc. The functional groups and the molecular weight of the polymers, control thek properties which vary in hydrophobicity, solubiUty characteristics, glass-transition temperature, and crystallinity. 

Phtha/k anhydride is the most important type of dibasic acid derivative ki alkyd preparation because of its low cost and the excellent overall properties it imparts to the reski. The anhydride stmcture allows a fast esterification to form half-esters at relatively low reaction temperatures without hberatkig water, thereby avoiding the danger of excessive foaming ki the reactor. However, skice the two carboxyl groups of phthaUc anhydride are ki the ortho position to each other on the benzene ring, cycHc stmctures may and do occur ki the reski molecules. 

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