Carboxylic acid amide phosphites

In an extension of earlier work, Buigada et al. have also reported on the reaction of the cyclic phosphite (66) with dimethylacetylene dicarboxylate (58) in the presence of proton sources such as carboxylic acids, amide N-H bonds in succinimide or phthalimide and amine N-H bonds in p UTole or indole. With carboxylic acids (67) a mixture of the ylid (68) and the cyclic phosphorane (69) was obtained and in some instances (e.g. with 2,4,6- trimethylbenzoic and p-methoxybenzoic acids) the ylid and phosphorane were shown to be in equilibrium. With amides as the proton source, ylids were generally formed although with N-methylbenzamide (PhCONHMe)a signal attributed to (70) was observed at = - 52 p.p.m. which had disappeared by the end of the reaction through rearrangement to (71). With amines (e.g. pyrrole) the products were again a mixture of ylid (72) and phosphorane (73) and the entire set of results was rationalised in terms of HSAB theory and the symbiotic effect around phosphorus. 

Enamines from thioimino-esters. - Vinylogous carboxylic acid amides. Startg. thioimino-ester dissolved in triethyl phosphite, and warmed 20 hrs. at 60° under Ng -> product. 

Electrophilic substitution of the ring hydrogen atom in 1,3,4-oxadiazoles is uncommon. In contrast, several reactions of electrophiles with C-linked substituents of 1,3,4-oxadiazole have been reported. 2,5-Diaryl-l,3,4-oxadiazoles are bromi-nated and nitrated on aryl substituents. Oxidation of 2,5-ditolyl-l,3,4-oxadiazole afforded the corresponding dialdehydes or dicarboxylic acids. 2-Methyl-5-phenyl-l,3,4-oxadiazole treated with butyllithium and then with isoamyl nitrite yielded the oxime of 5-phenyl-l,3,4-oxadiazol-2-carbaldehyde. 2-Chloromethyl-5-phenyl-l,3,4-oxadiazole under the action of sulfur and methyl iodide followed by amines affords the respective thioamides. 2-Chloromethyl-5-methyl-l,3,4-oxadia-zole and triethyl phosphite gave a product, which underwent a Wittig reation with aromatic aldehydes to form alkenes. Alkyl l,3,4-oxadiazole-2-carboxylates undergo typical reactions with ammonia, amines, and hydrazines to afford amides or hydrazides. It has been shown that 5-amino-l,3,4-oxadiazole-2-carboxylic acids and their esters decarboxylate. 

Activation of carboxylic acids with carbonyldiimidazole (equation 12) and subsequent reaction with amines gives amides and peptides in good yield. " Through the same intermediate, the activation also occurs with the more stable AA -oxalyldiimidazole and the mixture of triphenyl phosphite and imidazole. "... 

We have also shown that phosphites4), especially diphenyl and triaryl phosphites react non-oxidatively with carboxylic acids in the presence of pyridine to give acyl-oxy N-phosphonium salt of pyridine (5 and 6 in Scheme 2) accompanied by dephen-oxylation, which produces the corresponding amides and esters on aminolysis and alcoholysis. The structure of N-phosphonium salts such as 5 and 6 is presumed to result from the stoichiometric relationship among phosphites, pyridine, and the car-boxy component. 

In these reactions, hydrolysis of diphenyl and triaryl phosphites to monoaryl phosphites and phenol was coupled by dehydration between carboxylic acids and amines or alcohols to the corresponding amides and esters. Therefore, the reaction can be generalized as a hydrolysis-dehydration reaction (Scheme 2). The concept of the hydrolysis-dehydration reaction using phosphites has been drown to be applicable also to reactions with other phosphorus compounds such as phosphinites, phos-phonites and phosphorates s Aryl esters of these phosphorus compounds are effective as condensing agents in the production of carboxylic amides and esters (from carboxylic acids and amines or alcohols, respectively) whereas alkyl esters are ineffective (Eqs. (1-3)) ... 

Considering that the chemical reactivity of carboxylic acids is similar to that of carbonic acids, as is observed in amide and ester formation, we have attempted the substitution of carbon dioxide for carboxylic acids in the coupling reaction with amines by using phosphites in pyridine or imidazole, and found that ureas are in fact produced in good yields (Eq. (4))6. Similarly, carbon disulfide reacts with amines to yield the corresponding thioureas (Eq. (5)). 

Although the combined additive phosphonylation and esterification of an a,j5-unsatu-rated carboxylic acid by a trialkyl phosphite can thus easily, although not necessarily accurately, be envisaged, that of a similarly unsaturated ester, nitrile, or amide is perhaps not so readily apparent. Harvey showed that successful reaction between triethyl phosphite and such a substrate (Scheme 43) occurs in a protic medium. In this respect, the reactions proceed faster in methanol than in ethanol, but reactions are, in general, (including those of structurally analogous unsaturated ketones) much cleaner and faster when carried out in phenol, and also afford much higher yields in this solvent. It has also been shown that ammonium salts will also act as a proton source to allow completion of addition without alkylation. The later Russian workers used acetic acid with successful results ... 

The separation of gas mixtures by polymeric membranes has become a commercially important methodology for a number of different systems (1). Several recent review articles have discussed the interaction between polymer structure and gas permeability properties (2,3). The quantification of the effect of polymer structure on gas transport properties recently has been reported (4,5) and it is now possible to optimize gas transport properties for well defined polymeric materials. For those materials which do not have a well defined data base it is necessary to prepare and measure the gas transport properties. The polyamide-imides (PAI) are a class of polymeric materials which do not have an extensive data base for gas transport properties (6,7). Work by Yamazaki and coworkers (8) demonstrated that PAI materials could be prepared easily and in a manner whereby the amide bond could be prepared from a phosphite activated carboxylic acid and an aromatic amine. Yang and CO workers (9-11) have shown that novel dicarboxyl ic acids could be prepared from trimellitic acid anhydride (TMA) and aromatic diamines and that these dicarboxylic acids could be coupled with a second diamine to form regiospecific PAI materials. Our focus was to examine the effects of a phenylene diamine and its alkylated analogs on the gas transport properties of regiospecific PAI materials and to identify those structures which maximized both permeability and selectivity. 

For rigid PVC the extract will be much smaller, typically 1-5%, and will consist of lubricants such as long-chain aliphatic esters, e.g. glyceryl mono-ricinoleate, long-chain aliphatic acids and alcohols, and hydrocarbon and amide waxes. Metal-based stabilisers such as metal carboxylates or organo-tin compounds may be present. Also present may be nonmetal stabilisers such as ESBO, organic phosphites, bisphenol A, and polyols such as trimethylolpro-pane or pentaerythritol. 

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