Calcium carboxylic acid ester

Rovnyak GC, Atwal KS, Hedberg A et al (1992) Dihydropyrimidine calcium channel blockers. 4. Basic 3-substituted-4-aryl-l, 4-dihydropyrimidine-5-carboxylic acid esters. Potent antihypertensive agents. J Med Chem 35 3254-3263... 

Carboxylic acid esters from calcium carboxylates... 

Calcium oxide dimethyl sulfoxide Carboxylic acid esters from halides... 

The Bakelite Division of Union Carbide received US. Patent 2,462,331 on February 22, 1949, for the use of carboxylic acid esters or metal salts of carboxylic acids as additives to polyethylene, that improved the processing of polyethylene into film and sheets. The addition of 0.2-0.5 wt% of these compormds to polyethylene was reported to cause the ready release of the polyethylene film or sheet from hot milling and calendaring rolls at elevated temperatures (115-150°C) to provide films and sheets with good surface appearance. Examples of these releasing agents were calcium stearate, aluminum laurate and aluminum tristearate. 

Iodine lithium iodide calcium cabonate Ethylene derivs. from carboxylic acid esters with decarbalkoxylation... 

K.S. Atwal, G.C. Rovnyak, S.D. Kimball, D.M. Floyd, S. Moreland, B.N. Swanson, J.Z. Gougoutas, J. Schwartz, K.M. SmiUie, M.F. Malley, Dihydropyrimidine calcium channel blockers. 11. 3-Substituted-4-aryl-l,4-dihydro-6-methyl-5-pyrimidine carboxylic acid esters as potent mimics of dihydropyridines, J. Med. Chem. 33 (1990) 2629-2635. 

Carboxylic Acid Group. Sorbic acid undergoes the normal acid reactions forming salts, esters, amides, and acid chlorides. Industrially, the most important compound is the potassium salt because of stabiUty and high water solubiUty. Sodium sorbate [7757-81-5] (E,E form [42788-83-0]) is less stable and not commercially available. The calcium salt [7492-55-9] which has limited solubiUty, has use in packaging (qv) materials. 

The most common impurities are the corresponding acid and hydroxy compound (i.e. alcohol or phenol), and water. A liquid ester from a carboxylic acid is washed with 2N sodium carbonate or sodium hydroxide to remove acid material, then shaken with calcium chloride to remove ethyl or methyl alcohols (if it is a methyl or ethyl ester). It is dried with potassium carbonate or magnesium sulfate, and distilled. Fractional distillation then removes residual traces of hydroxy compounds. This method does not apply to esters of inorganic acids (e.g. dimethyl sulfate) which are more readily hydrolysed in aqueous solution when heat is generated in the neutralisation of the excess acid. In such cases, several fractional distillations, preferably under vacuum, are usually sufficient. 

Carbenicillin Carbenicillin, [25 -(2a,5a,6j3)]-3,3-dimethyl-7-oxo-6-(2-carboxy-2-phenylacetamido)-4-thia-l-azabicyclo[3.2.0]-heptan-2-carboxylic acid (32.1.1.32), is synthesized by direct acylation of 6-APA in the presence of sodium bicarbonate by phenylmalonic acid monobenzyl ester chloride, which forms the benzyl ester of carbenicillin (32.1.1.31), the hydrogenolysis of which using palladium on carbon or calcium carbonate as catalyst gives the desired product (32.1.1.32) [51-58]. 

These chelates are structurally similar to that postulated above for the metal ion-catalyzed hydrolysis of oj-amino esters the position of the protons in the transition state is different, but this is a completely arbitrary distinction. A further distinction is that the metal ion is facilitating attack in this instance not by a polarization of the substrate molecule, but rather by the positioning and fixation of the hydroxide ion at the reaction site. It is not clear which of these two representations—for the amino acid esters involving polarization or for the carboxylate esters involving fixation of the hydroxide ion—is the correct interpretation. It is conceivable that both are correct. A similar explanation will account for the large effect of calcium ions on the alkaline hydro ysis of acetylcitric and benzoyl-citric acids (53). 

Most thermal stabilizers for poly (vinyl chloride) are metal salts of carboxylic acids or mercaptans. The commonly used metals are cadmium, barium, zinc, lead, calcium, and dibutyltin. Originally it was assumed the metal salts act as scavengers for hydrogen chloride. However, Frye and Horst (7, 8) found evidence for the introduction of ester groups in the polymer from metal carboxylate stabilizers, which led them to postulate that thermal stabilizers function by substituting the unstable chlorine atoms with the ligands of the stabilizer to yield derivatives which are more thermally stable than the original chloride. 

Carbon-11 labelled calcium channel antagonists C-nifedipine, C-nisoldipine, C-nitrendipine and C-CFj-nifedipine possessing vasodilating and hypotensive properties have been synthesized using a modified Hantzsch-type cyclocondensation proce-dure . Condensation of aldehydes 242, 243 and 244 with 3-aminocrotonic acid esters 245, 246, 247 and with acetoacetic ester 248 produced in one pot after 12 hours reflux in dry ethanol the methyl sulphonylethyl protected dihydropyridines 249-252. Deprotection of the carboxylic acids by alkaline hydrolysis followed by conversion into the dihydropyridine monocarboxylic acids 253-256 gave potassium salts in situ, and subsequent methylation with CH3I produced the corresponding labelled title compounds 257-260 (equation 102),... 

---