Combination tables carboxylic acids

The observation that addition of imidazoles and carboxylic acids significantly improved the epoxidation reaction resulted in the development of Mn-porphyrin complexes containing these groups covalently linked to the porphyrin platform as attached pendant arms (11) [63]. When these catalysts were employed in the epoxidation of simple olefins with hydrogen peroxide, enhanced oxidation rates were obtained in combination with perfect product selectivity (Table 6.6, Entry 3). In contrast with epoxidations catalyzed by other metals, the Mn-porphyrin system yields products with scrambled stereochemistry the epoxidation of cis-stilbene with Mn(TPP)Cl (TPP = tetraphenylporphyrin) and iodosylbenzene, for example, generated cis- and trans-stilbene oxide in a ratio of 35 65. The low stereospecificity was improved by use of heterocyclic additives such as pyridines or imidazoles. The epoxidation system, with hydrogen peroxide as terminal oxidant, was reported to be stereospecific for ris-olefins, whereas trans-olefins are poor substrates with these catalysts. 

Another class of hydrocarbon binders used in propints are the carboxy-terminated polybutadiene polymers which are cross-linked with either tris[l-(2-methyl)aziridinyl] phosphine oxide (MAPO) or combinations with phenyl bis [l -(2-methyl)aziridinyl] phosphine oxide (Phenyl MAPO). Phenyl MAPO is a difunctional counterpart of MAPO which makes possible chain extension of polymers with two carboxylic acid groups. A typical propint formulation with ballistic properties is in Table 11 (Ref 83) Another class of composites includes those using hydroxy-terminated polybutadienes cross-linked with toluene diisocyanate as binders. The following simplified equations illustrate typical reactions involved in binder formation... 

Similarly, Dakka and coworkers oxidized a variety of substituted toluenes to the corresponding carboxylic acids using a Co /QBr catalyst in combination with dioxygen at 137-170 °C (Table 1). 

The pH of the medium always has a strong effect on metal binding. Competition with protons means that metal complexes tend to be of weak stability at low pH. Anions of carboxylic acids are completely protonated below a pH of 4 and a metal can combine only by displacing a proton. However, at pH 7 or higher, there is no competition from protons. On the other hand, in the case of ethylenediamine, whose pKa values are 10.2 and 7.5 (Table 6-9), protons are very strong competitors at pH 7, even with a strongly com- c... 

A mixture of 1.42 g (0.01 mol) phosphorus pentoxide and 2.5 g of chromatography grade silica gel was placed in a flask and stirred for 30 min. A mixture of equimolar amounts (5 mmol) of the carboxylic acid and phenol was added. Usually an immediate color change was observed. After stirring for 6 h at the temperature indicated in the Table, methylene chloride (50 mL) was added. The mixture was stirred for 1 min and then filtered. The spent reagent was washed twice with methylene chloride (10 mL). The combined organics were washed with aqueous NaOH solution, water and dried over sodium sulfate, and the solvent was removed under reduced pressure. 

The 180 IEs on the acidities of carboxylic and phosphoric acids are a combination of primary and secondary. They are primary to the extent that it is an lsO-H bond that is broken, but they are secondary to the extent that an 180 remains in the carbonyl or phosphoryl bond. Despite this ambiguity, such IEs are included in Table 8, where each carboxyl has two 18Os and each phosphate has four. This experimentally observed 1% IE per lsO in carboxylic acids found application in studies of the symmetry of hydrogen bonds in monoanions of dicarboxylic acids.73 78 The relative contributions of primary and secondary IEs to the observed IE are considered below. 

A 16,000-member library was synthesized using this procedure. Twenty-one halonitrobenzenes were combined with 20 halides and half were converted to the sulfone, resulting in 840 3-amino-l,5-benzothiazepine derivatives. These were then reacted with 19 carboxylic acids. Table V shows a representative example of the reagents used. A small random sample of 480 compounds from the library was analyzed by HPLC/MS. Figure 4 shows the purity distribution for the library. Most of the compounds were prepared in high purity. 

The polymerisation of a-aminoacid A-carboxyanhydride, which is accompanied with the elimination of carbon dioxide, constitutes a convenient method for preparing high molecular weight polypeptide. This polymerisation, with the use of a-aminopropionic acid (alanine) A-carboxylic acid anhydride as a monomer, was also carried out in the presence of coordination catalysts such as group 2 and 3 metal alkyls [168-174] or their combinations with water, secondary amine or alcohol [168,173] and yielded polyalanine (Table 9.2). 

TABLE XXVI. 3-PyTazolin-5-ones. Halogen and Halogen Combined with Carboxylic Acid and Derivatives... 

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