Acids, amino polybasic

The last case illustrates the complicated behavior possible if both intra- and intermolecular H bonding are present. Such combinations, called mixed association by Lutskil (1274), are common among compounds with several proton donor and acceptor groups. Forecasting which type will dominate is difficult. Other examples besides the phos-phonic acids are dihydroxy, hydroxy, or amino acids, and polybasic acids. 

Solutions of polyelectrolytes contain polyions and the free (individual) counterions. The dissociation of a polyacid or its salt yields polyanions, and that of a polybase or its salt yields polycations, in addition to the simple counterions. The polyampholytes are amphoteric their dissociation yields polyions that have anionic and cationic functions in the same ion and often are called zwitterions (as in the case of amino acids having HjN and COO groups in the same molecule). Such an amphoter will behave as a base toward a stronger acid and as an acid toward a stronger base its solution properties (particularly its effective charge) will be pH dependent, and an isoelectric point (pH value) exists where anionic and cationic dissociation is balanced so that the polyion s charges add up to zero net charge (and solubility is minimal). 

SYNTHESIS OF MIXED OXIDES USING POLYBASIC CARBOXYLIC HYDROXY-AND AMINO-ACID ROUTES PROBLEMS AND PROSPECTS... 

Polybasic carboxylic hydroxy and amino acid aided synthetic routes directed towards obtaining mixed inorganic materials, especially for battery and fuel cell applications, are overviewed. It has been shown that, in spite of enormous number of papers on the subject, significant efforts should be undertaken in order to understand the basic principles of these routes. Possible influence of the structure of reactants employed in the process (acids, poly hydroxy alcohols, metal salts) is put forward, and some directions of future work in the field are outlined. 

Dissolution of metal salts in the aqueous solution of polybasic hydroxy (or amino) carboxylic acids (and poly hydroxy alcohols) ... 

Role of Polybasic Carboxylic Hydroxy (amino) Acids and Poly Hydroxy Alcohols... 

It should be emphasized that citric acid is not the only possible acid employed in Pechini-type syntheses. Other polybasic carboxylic hydroxy acids (malic, tartaric, hydroxyglutaric, etc.) and polybasic carboxylic acids (e.g., succinic) have been probed in Refs. [4, 13-16], As far as amino acids are concerned, glycine seems to remain the only representative [13, 14]. However, the choice of each particular organic acid has never been justified, and no comparative studies are performed in order to find possible dependencies of the process (ability to form a sol, a gel, or a resin, easiness of thermal decomposition of precursors, etc.) on the steric factors, specifically, on the number of hydroxy and carboxylic groups in the molecule of an acid, as well as on the length of its carbon skeleton. 

Famesylation of the Ras protein occurs at the C-terminal CAAX sequence (A aliphatic amino acid, X Ser or Thr). The famesyl residue is attached, with the help of a farnesyl protein transferase, via a thioether bond to the Cys residue of the CAAX sequence. Next, the last three amino acids are cleaved off by proteases and the carboxyl group of the C-terminal cysteine residue undergoes a methylesterification (Fig. 9.6). In addition, the Ras proteins have a palmitinic acid anchor at different Cys residues in the vicinity of the C terminus. The membrane localization of the Ki-Ras protein is also supported by a polybasic sequence close to the C terminus (see 3.7 and Fig. 3.12). 

The lower members of the homologous series of 1. Alcohols 2. Aldehydes 3. Ketones 4. Acids 5. Esters 6. Phenols 7. Anhydrides 8. Amines 9. Nitriles 10. Polyhydroxy phenols 1. Polybasic acids and hydro-oxy acids. 2. Glycols, poly-hydric alcohols, polyhydroxy aldehydes and ketones (sugars) 3. Some amides, ammo acids, di-and polyamino compounds, amino alcohols 4. Sulphonic acids 5. Sulphinic acids 6. Salts 1. Acids 2. Phenols 3. Imides 4. Some primary and secondary nitro compounds oximes 5. Mercaptans and thiophenols 6. Sulphonic acids, sulphinic acids, sulphuric acids, and sul-phonamides 7. Some diketones and (3-keto esters 1. Primary amines 2. Secondary aliphatic and aryl-alkyl amines 3. Aliphatic and some aryl-alkyl tertiary amines 4. Hydrazines 1. Unsaturated hydrocarbons 2. Some poly-alkylated aromatic hydrocarbons 3. Alcohols 4. Aldehydes 5. Ketones 6. Esters 7. Anhydrides 8. Ethers and acetals 9. Lactones 10. Acyl halides 1. Saturated aliphatic hydrocarbons Cyclic paraffin hydrocarbons 3. Aromatic hydrocarbons 4. Halogen derivatives of 1, 2 and 3 5. Diaryl ethers 1. Nitro compounds (tertiary) 2. Amides and derivatives of aldehydes and ketones 3. Nitriles 4. Negatively substituted amines 5. Nitroso, azo, hy-drazo, and other intermediate reduction products of nitro com-pounds 6. Sulphones, sul-phonamides of secondary amines, sulphides, sulphates and other Sulphur compounds... 

The procedure just described has been used for the determination of the dissociation constants of a number of weak monobasic acids. It has also been extended to the study of polybasic acids and amino-acids. 

Let us consider a case of the interaction of polybasic molecules (which are all amino acids and proteins [39,40]), with adsorption surface sites. As an example, let us consider the dissociation of a tribasic molecule (lysine, arginine) ... 

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