COOH group,

The methyl group in p-toluic acid may be oxidised to a -COOH group forming p-phthalic (or tere-phthalic) acid, C H4(C.OOH), but the oxidation is usually slow. 

When an aromatic compound having an aliphatic side chain is subjected to oxidation, fission of the side chain occurs between the first and second carbon atoms from the benzene ring, the first carbon atom thus becoming part of a carboxyl ( -COOH) group. For example ... 

This reaction illustrates the conversion of the —COCH3 group into the —COOH group by means of a hypohalite ... 

Carboxylate exchangers contain —COOH groups which have weak acidic properties and will only function as cation exchangers when the pH is sufficiently high (pH > 6) to permit complete dissociation of the —COOH site. Outside this range the ion exchanger can be used only at the cost of reduced capacity. 

Uses. Malonic acid is used instead of the less expensive malonates for the introduction of a CH—COOH group under mild conditions by Knoevenagel condensation and subsequent decarboxylation. The synthesis of 3,4,5-trimethoxycinnaniic acid, the key intermediate for the coronary vasohdator Cinepa2et maleate [50679-07-7] (5) involves such a pathway (13). 

One widely used method of formation of protected compounds involves polymer-supported reagents, with the advantage of simple workup by filtration and automated syntheses, especially of polypeptides. Polymer-supported reagents are used to protect a terminal — COOH group as a polymer-bound ester (RCOOR —( ) during peptide syntheses, to protect primary alcohols as... 

In an attempt to synthesize the macrolide antibiotic chlorothricolide, an unhindered —COOH group was selectively protected, in the presence of a hindered —COOH group, as a MEM ester that was then reduced to an alcohol group. ... 

The p-bromobenzyl ester has been used to protect the /3-COOH group in aspartic acid. It is cleaved by strong acidic hydrolysis (HF, 0°, 10 min, 100% yield), but is stable to 50% CF3COOH/CH2CI2 used to cleave /-butyl carbamates. It is 5-7 times more stable than a benzyl ester. ... 

Stannyl esters have been prepared to protect a —COOH group in the presence of an —NH2 group [(n-Bu3Sn)20 or -Bu3SnOH, reflux, 88%]. Stannyl esters... 

We also have to count on variations of the main monomer unit as well. For example, HEMA materials always contain traces of unesterified free carboxylic groups. These acidic groups interact with polycations. As result, retardation is observed until total adsorption of the injected sample. Consequently, polycations can be analyzed on such a material only in acidic eluents, where the dissociation of the — COOH— group is suppressed. 

Note that the dissociation constants of both the a-carboxyl and a-amino groups are affected by the presence of the other group. The adjacent a-amino group makes the a-COOH group more acidic (that is, it lowers the pAl, ) so... 

Stannyl esters have been prepared to protect a -COOH group in the presence of an -NH2 group [( -Bu3Sn)20 or -Bu3SnOH, CgH, reflux, 88%]. Stannyl esters of A -acylamino acids are stable to reaction with anhydrous amines and to water and alcohols aqueous amines convert them to ammonium salts. Stannyl esters of amino acids are cleaved in quantitative yield by water or alcohols (PhSK, DMF, 25°, 15 min, 63% yield or HOAc, EtOH, 25°, 30 min, 77% yield). ... 

A side-chain COOH group in 5//-pyrido[l,2,3- 7e]-l,4-benzoxazin-5-one was reduced into a HOCH2 group with NaBH4 in a 1 1 mixture of MeOH and THE at 5°C (98MIP13). Ethyl 7-oxo-2,3,6,7-tetrahydro-5//-pyr-ido[l,2,3- 7e]-l,4-benzoxazine-2-carboxylate was prepared by the catalytic hydrogenation of the l-oxo-5H derivative over 10% Pd/C catalysts in EtOH (99EUP894796). 

The physico-mechanical, thermal, and adhesion properties of the synthesized polyfunctional PSs are dependent on the nature of functional groups in the aromatic ring. In this case, the following are properties of the chlorohydrin and epoxy groups highest elasticity, resistance to strike, and adhesion properties with carboxyl and olefinics. Furthermore, the—CO—CH=CH-—COOH group was provided new properties such as the photosensitive capability. Functionalized PSs obtained are characterized by their high thermostability, adhesion, and photosensitivity. 

When —CO—CH=CH—COOH groups bonded to the aromatic ring of PS, the physico-mechanic, thermal, and adhesion properties increased from 4.5 mol% to 20.0 mol%. This caused the following changes the resistance of PS increased from 14.0 to 19.2 kJ/m, the resistance to stretch polymer material itself increased from 35.0 to... 

Figure 7 The physico-mechanical properties of —CO—CH=CH—COOH groups polystyrenes (O, —) resistance to stretch, (cr) (A—) resistance to strike, (a) (A—) relative extention, (e) ( —) hardness (He) ( —-) adhesion, (A).

The diffusion of electrons plays a major role in the surface treatment of polymers in a gas plasma apparatus. The adhesion of PE tapes increases to a maximum by this treatment at 0.20 to 0.30 A for 20 to 30 s [40]. IR absorption at 1600-1750 cm increases 1.5-fold on discharge treatment owing to the formation of polar >C==0 and —COOH groups, which increase tape adhesion. 

In sodium formate, and in various COOH groups, the distance between the carbon oxygen nuclei is found to be about 1.27 angstroms, the O—C—O angle being in neighborhood of 125°. L. Pauling, The Nature of the Chemical Bond, 2d ed., 32, Cornell University Press, 1940. 

If a proton is removed from one COOH group, as shown in Fig. 466, and transferred to a distant water molecule to form (HjO)+, the symmetry of the molecule is lost. On the other hand, if the proton is now removed from the other COOH group and transferred to a water mole-... 

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