Sodium barium carboxylates

When the MA6 film is neutralized by sodium hydroxide, one observes not only a substantially smaller initial value of D, but also a very pronounced decrease in D throughout the interdiffusion process. Moreover, this diffusion is retarded even further in the case of the barium carboxylate film. Here the initial D value is ca cm /s, and appears to... 

Barium oxide and sodium hydride are more potent catalysts than silver oxide. With barium oxide catalysis, reactions occur more rapidly but O-acetyl migration is promoted. With sodiun hydride, even sterically hindered groups may be quantitatively alkylated but unwanted C-alkylation Instead of, or in addition to, 0-alkylatlon is a possibility. Sodium hydroxide is a suitable catalyst for the alkylation of carboxylic acids and alcohols [497J. 

The predicted configuration for the carboxylate ion group is that with the angle O—C=0 equal to 125°16 and each C—O bond length equal to 1.27 A. (The single-bond and double-bond lengths are 1.41 A and 1.21 A, respectively.) The experimental values lie close to these for example, for the formates of sodium, calcium, strontium, and barium the average values are 125.5° 1° and 1.25 0.01 A, respectively.81... 

Since the proteins contain negatively charged groups such as phosphates, side-chain carboxyls, terminal carboxyls, and sulfhydryls, they bind a number of different cations, such as calcium, barium, strontium, magnesium (Dickson and Perkins 1969), copper (Dill and Simmons 1970 Aulakh and Stine 1971), thallium (Sundararajan and Whitney 1969), potassium and sodium (Ho and Waugh 1965), iron (Basch et al. 1974, Demott and Park 1974 Demott and Dincer 1976), cadmium (Roh et al. 1976), and mercury (Roh et al. 1975). 

The four-membered azetidine ring remains unaffected by sodium in liquid ammonia, 94 methanolic ammonia, 95 5M barium hydroxide at 100 °C for 24 hours, 87 sodium hydroxide under ester saponification conditions, 87 HC1 at room temperature, 96,97 catalytic hydrogenation under normal conditions, 87,95 and ozonolysisJ87 Correspondingly, as observed for proline, the azetidine-2-carboxylic acid (2) raises no particular difficulties in the synthesis of related peptides. 

Azetidine-2-carboxylic acid (2) like proline gives an intense blue color with sodium nitroprusside in 10% acetaldehyde solution in the presence of sodium carbonate. 98,99 Upon usual acid hydrolysis (6M HC1, 110 °C, 24 h or more) as required for amino acid analysis, azetidine-2-carboxylic acid is completely decomposed, yielding mainly homoserine lactone, as well as other ninhydrin-positive compounds. 87,89,99 To enable an accurate quantification of this imino acid, azetidine-2-carboxylic acid peptides should be hydrolyzed by alkali (5M barium hydroxide, at 100 °C for 18 h 89 or 2 M sodium hydroxide at 110°C for 22h 100 ). There are extensive NMR spectroscopic data available 100-104 and the absolute configurations of A-acetyl-L-azetidine-2-carboxylic acid 105 and A-terf-butoxycarbonyl-L-azetidine-2-car-boxylic acid 106 have been determined by X-ray analysis. 

When treated with sodium metaperiodate, the barium salt of orotidine consumes one mole of oxidant per mole without the liberation of formic acid, in accord with a pentofuranosyl structure.119 The structure of orotidine, therefore, is certainly l-(D-ribofuranosyl)uracil-6-carboxylic acid (XXXII). 

The decarboxylation of simple aliphatic acids by fusion of their sodium salts with sodium hydroxide does not give pure hydrocarbons. By heating the barium salts of 1-phenylcycloalkane-l-carboxylic acids with dry sodium methoxide, 1-phenylcycloalkanes are obtained in 6-64% yields, the yield increasing with the size of the alicyclic ring. The coupling of the... 

Hydrolysis by alkali The usual reagent is a solution of sodium hydroxide or potassium hydroxide in water or an alcohol (methanol, ethanol, or diethyleneglycol). Milder reagents are solutions of barium or calcium hydroxide. If fission of an ester gives products that are sensitive to strong alkali, it can often be effected with advantage by a solution of sodium carbonate, sodium hydrogen carbonate, or sodium methoxide.52 For hydrolysis of particularly stable esters, such as n,n -disubstituted aromatic carboxylic esters, it is sometimes necessary to use an alkali melt. 

The four carboxylic groups of the tetraacid (3) can be easily neutalized by the proper base in ethanol/water and therefore salts of several cations could be prepared without difficulties. They show in water at 20 C a solubility (mmol/1) of 5.0 for lithium, 2.2 for ammonium, 2.0 for cesium and potassium, 0.5 for sodium and 0.2 for barium cations. 

Resins based on para-substituted phenols can be either one-step or two-step, but they cannot cure to a thermoset state. In the manufacture of phenolic resins, smaller quantities of acetaldehyde and furfuraldehyde are used in addition to formaldehyde. Furthermore, resorcinol, bisphenol A, and p-alkylphenols are employed, in addition to phenol, when special properties are desired. Formaldehyde concentrations of 37-50 weight % in aqueous solutions are most commonly employed. The catalysts most frequently used are acids such as oxalic, hydrochloric, sulfuric, p-toluenesul-fonic, and phosphoric and bases such as sodium, calcium, and barium hydroxide. In the weakly acidic range metal carboxylates are employed. Thermoset phenolic resins are employed as structural adhesives for laminating and bonding applications. Para-alkyl-substituted resins are employed as tackifiers in contact adhesives, pressure-sensitive adhesives, and hot-melt adhesives. 

Other reagents that open the epoxide ring with substitution, to give the useful derivatives indicated in parentheses, include phenols (phenyl ethers) (81) y carboxylic acids (esters) (8 ), hydrogen sulfide in the presence of barium hydroxide (thiols) (82), sodium methyl mercaptide (methyl thio-ethers) (83), dipotassium hydrogen phosphate or dibenzylphosphoric acid (phosphate esters) (84), alkyl or aryl magnesium halides (halodeoxysugars)... 

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