Acid, carboxylic ratios

Unsaturated polyesters were obtained by reacting the glycolyzed product widi maleic anhydride at a hydroxy-to-carboxyl ratio of 1 1. The hydroxyl number was determined without separation of die free glycol. The polyesterification reaction was conducted in a 2-L round-bottom dask equipped with a condenser, a gas bubbler, a thermowell, and a stirrer. The reaction mixture was heated from room temperature to 180°C in about 1-1.5 h. The temperature was maintained at 180°C for about 3 h, dien raised to 200°C and maintained until die acid value reached 32 mg KOH/g. 

Pyrrole-2-carboxylate decarboxylase attains equilibrium in the course of either decarboxylation or carboxylation (Fig. 8). The decarboxylation of 100 mM pyrrole-2-carboxylate was in equilibrium after Ih, resulting in an equilibrium constant of 0.3 M." Due to this balanced equilibrium, the enzyme also catalyzed the reverse carboxylation of pyrrole after the addition of HCO3, leading to a similar equilibrium constant of 0.4 M and a shift of the [pyrrole]/[pyrrole-2-carboxylate] ratio toward the acid. 

Gamma radiolysis of simple carboxylic acids and N-acetyl amino acids results in loss of the carboxyl group with formation of carbon monoxide and carbon dioxide. In the carboxylic acids, the ratio of C0/C02 produced is approximately 0.1, while in the N-acetyl amino acids the ratio is much smaller. In the poly carboxylic acids and poly amino acids, radiolysis also results in the loss of the carboxyl group, but here the ratio of C0/C02 is greater than 0.1. Incorporation of aromatic groups in the poly amino acids provides some protection for the carboxyl group. The degradation of the poly acids is believed to involve radical and excited state pathways. 

The carboxylic acids were combined with hexylamlne and water in order to study the association structures formed. The hexyl-amine was chosen because it did not by Itself form a liquid crystalline phase with water. Fig. 3A. Water dissolves in the amine to a maximum of 60% to form an isotropic solution. The liquid crystal is formed first at a certain octanoic acid amine ratio, approximately 0.1. The liquid crystalline phase forms a large region reaching to a weight fraction of 0.61 of the acid, corresponding to a 1 1 molar ratio of the two species. 

For the solid-phase synthesis of amides, it makes a significant difference whether the amine or the acid is linked to the support. Resin-bound amines are readily acy-lated by adding first a carboxylic acid and then a carbodiimide (Table 13.3). The acid/ carbodiimide ratio is not critical, because both the O-acylisourea (ratio 1 1) and the symmetric anhydride (ratio 2 1) will lead to N-acylation. It should, however, be borne in mind that the half-lives of O-acylisoureas are shorter than those of anhydrides, and for difficult couplings it might be advantageous to acylate with a symmetric anhydride (two equivalents of acid and one of carbodiimide). 

The Henderson-Hasselbalch equation described in Section 19.4 can be applied to bases such as amines, as well as carboxylic acids. The ratio [CH3NH3+]/[CH3NH2] is given by... 

Based on this assumption and conformation C (Figure 2) we can calculate that the sample MD 120 has = 15 % of the chains entrapped in the micelle. This is in agreement with the fact that this diacid sample has the highest hydroxy-to-acid index ratio and thus a slight excess of non-carboxylated chains (see Table I). 

Eudragit PS 30D is the aqueous dispersion of an anionic copolymer based on methyl acrylate, methyl methacrylate, and methacrylic acid. The ratio of free carboxyl groups to ester groups is approximately 1 10. It has been designed for the use in enteric-coated solid-dosage forms and dissolves in aqueous systems at pH >7. 

Adducts (6) and (7) from amides and chlorophosphoric acid aiyl esters or dichlorophosphoric acid aryl esters respectively are well known. - The adducts are formed in a 1 1 ratio. They have been applied to the synthesis of mixed anhydrides from diarylphosphoric acids and carboxylic acids, as well as mixed substituted esters of pyrophosphoric acid. The adduct formation between primary or secondary carboxamides and dichlorophosphates has been used to prepare nitriles and isonitriles respectively. The adduct from DMF and phenyldichlorophosphate is a useful reagent for the preparation of carboxylic acid esters from the corresponding acids and alcohols, 3-lactams from imines and carboxylic acids," carboxylic acid anhydrides, carboxylic acid esters and thiol esters. Adducts of amides with ester amides or diamides of chlorophosphoric acid have been studied. ... 

The first step in the decomposition of nitrosoamides 123) is formation of the diazo ester 125) which fragments to a diazonium ion pair (128)129 The ion pairs thus produced differ from those obtained in the reaction of diazoalkanes with acids. The ratio of ester to ether formed in the decomposition of rV-nitroso-fV-benzhydrylbenz-amides in alcohol is lower than that found in the reaction of diphenyldiazomethane 132) with acids, and in the solvolysis of benzhydryl benzoate (I35)135,136 This effect has been attributed to the intervention of trans-diazo ester in the decomposition of 125) which leads to a greater distance between carbocation and carbox-ylate anion. In the diazoalkane reaction attack of the acid occurs at the electron-rich carbon atom to generate the carboxylate in the immediate vicinity of the incipient carbocation. 

Fulvic acid contains less H, N, and S but more 0 than HA and humin the total acidity and ratio of carboxyl to phenolic hydrohyl groups is almost 3 for FA but near 2 for two other fractions. 

For the degradation of carboxylic acid, factors that may affect the reaction outcome are the ratio of sulfuric acid/carboxylic acid, the reaction temperature and the dilution extent of sulfuric acid. Even though some of the Schmidt degradations of carboxylic... 

Carboxylic acid Molar ratio DS Solnbility in CHCI3... 

Entry Carboxylic acid Molar ratio Product... 

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