Acetylenes formation form carboxyl

Such an easy isomerization of acetylenylbenzoic acid amides implies the formation of a five-membered nonaromatic ring condensed with the pyrazole ring. However, the pyrazole analog of o-iodobenzamide (amide of 4-iodo-l-methylpyrazole-3-carboxylic acid) formed under heating with CuC=CPh in pyridine for 9 h only the disubstituted acetylene in 71 % yield is identical in all respects to the compound obtained from the corresponding acid by successive action of SOCI2 and NH3 (90IZV2089) (Scheme 126). 

Acetylenes can also be carboxylated in the presence of dicobalt octacarbonyl. A patent (105) described the formation of acrylic and succinic acids from acetylene. Cyclopentanone was also formed in the presence of solvents (acetone, dioxane). Substituted succinic acids were formed from the corresponding substituted acetylenes. 

In just the same way two or more mechanisms of coke formation were observed in the decomposition of the naphthenes, of the paraffin hydrocarbons, olefins, acetylene, carboxylic acids, etc. In all cases the mechanisms of coke and tar formation could be represented by a cyclic sequence of a number of elementary stages, which involve the addition of every new molecule of the coke-forming material. Depending on whether the initial organic substance when the temperature is rising can give one, two, or more kinds of molecules of coke-forming material capable of... 

Figure 7.8. The oxidation of terminal acetylenes, and even some internal acetylenes, results in the formation of ketene intermediates that react with water to give the carboxylic acids (see Chapter 6). It appears that the ketenes also react with active-site residues, inactivating the P450 enzyme that forms them. The hydrogen that undergoes a 1,2-migration during the oxidation reaction is indicated by a star. The structures of 2-ethynylnaphthalene and 10-undecynoic acid, both of which inactivate P450 enzymes, at least in part by this mechanism, are shown.

The literature contains very little information about the mass spectra of furan compounds substituted with an unsaturated chain. The fragmentation mode of some 2-styryl- and 2,5-di-styrylfuran derivatives has been studied <920MS(27)615>. Each styryl substituent has an a-carboxylic acid or methyl carboxylate substituent. The molecular ion is the base peak for styryl and distyryl derivatives and the distyryl species show less fragmentation than the styryl species. An important fragmentation pathway for both these derivatives, in addition to simple bond cleavage, is the loss of formic acid or methyl formate, presumably forming acetylenic fragments (Schemes 1 and 2). 

It is believed that a strong base such as KOH or potassium alkoxide will deprotonate the active hydrogen from the reactants, such as alcohols, thiols, amines, carboxylic acids, and phenols, to generate the nucleophiles that add to acetylene, as illustrated by the formation of vinyl ether from alcohol and acetylene. This can qualitatively explain the reactivity order among primary, secondary, and tertiary alcohols, without considering the steric hindrance. It is known that tertiary alcohol is less acidic than secondary and primary alcohol, therefore, less potassium f-butoxide will be formed than primary potassium alkoxide from KOH. ... 

Saturated solutions of acetylene in water were irradiated for several hours by a 125-W UV lamp [83]. Photopolymerization was followed by UV-vis spectroscopy and different polymerization pathways involving diacetylene, vinylacetylene, and cumulene formation were discussed. The evaporation of the solvent from the resulting milky white solution of photopolymer resulted in the isolation of a cream-colored powder of acetylene photopolymer that was insoluble in common solvents. This photopolymer was characterized by elemental analysis, FTIR, and UV spectroscopy and was found to incorporate about 18% oxygen (probably from water) in the form of ketone, carboxyl, hydroxyl, and ether derivatives. FTIR spectroscopy revealed the structural similarity of acetylene photopolymer and a linear PA oxi-... 

The formation from pyrroles and dienophiles of substances which are the results of Michael addition has been mentioned (p. 70). In some cases Diels-Alder addition does occur. Thus, with methyl acetylenedicarboxylate, methyl pyrrole-1-carboxylate gives (50), formed by elimination of acetylene from the initial Diels-Alder product . From 1-methylpyrrole, (51) is obtained , formed from the initial Diels-Alder product by reaction with a second molecule of methyl acetylenedicarboxylate . 1-Benzylpyrrole... 

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