Acetal, 17-21, formation interchange

The objectives of this study were to extend these synthetic methods to the preparation of low molecular weight, hydroxy-terminated polymers containing acetylenic bonds and evaluating these prepolymers in castable solid propellant formulations. Since 2-butyne-l,4-diol was commercially available, the formation of polyacetals from this glycol seemed to be an attractive route to the desired polymers. It was believed that the rigid triple bond would inhibit the cyclic acetal formation observed by the earlier workers with the lower members of the saturated glycol series. Thus, in an acetal interchange reaction a linear polymer (I) should be favored over the cyclic acetal (II) ... 

Ru(edta)(H20)] reacts very rapidly with nitric oxide (171). Reaction is much more rapid at pH 5 than at low and high pHs. The pH/rate profile for this reaction is very similar to those established earlier for reaction of this ruthenium(III) complex with azide and with dimethylthiourea. Such behavior may be interpreted in terms of the protonation equilibria between [Ru(edtaH)(H20)], [Ru(edta)(H20)], and [Ru(edta)(OH)]2- the [Ru(edta)(H20)] species is always the most reactive. The apparent relative slowness of the reaction of [Ru(edta)(H20)] with nitric oxide in acetate buffer is attributable to rapid formation of less reactive [Ru(edta)(OAc)] [Ru(edta)(H20)] also reacts relatively slowly with nitrite. Laser flash photolysis studies of [Ru(edta)(NO)]-show a complicated kinetic pattern, from which it is possible to extract activation parameters both for dissociation of this complex and for its formation from [Ru(edta)(H20)] . Values of AS = —76 J K-1 mol-1 and A V = —12.8 cm3 mol-1 for the latter are compatible with AS values between —76 and —107 J K-1mol-1 and AV values between —7 and —12 cm3 mol-1 for other complex-formation reactions of [Ru(edta) (H20)]- (168) and with an associative mechanism. In contrast, activation parameters for dissociation of [Ru(edta)(NO)] (AS = —4JK-1mol-1 A V = +10 cm3 mol-1) suggest a dissociative interchange mechanism (172). 

Pappo, Bloom, and Johnson effected acetylation of the 3/3-hydroxyl group of the steroid dienic acid (1) by ester interchange with excess phenyl acetate in the presence of sodium hydride. Conventional acetylation is complicated by the formation of a mixed anhydride and the necessity for a step of selective hydrolysis. 

Should structure LXXIX find acceptance, an examination of the previous work will disclose where revisions are necessary. Although dihy-drostrychnidine-D may still be expressed by LXVIII (minus the metho-acetate), yet the hypothesis of a structural isomerism if favored, and hence the structures LXVI and LXVIII, for dihydrostrychnidine-A and -D, must be interchanged. Secondly, the structure of the dibenzylidene derivative of LXXXVII must be altered to meet the demands of the new formula. Thirdly, the formation of a ketoamide in the perbenzoic acid oxidation of methoxymethyldihydroneostrychnine is not readily understandable if the double bond is in the neo position (this tends to favor A " for the neo position of the double bond). 

Commercial amyl formate is an anhydrous, colorless liquid composed of a mixture of isomeric amyl formates with the isoamyl formate in predominance. This mixture is miscible with oils, hydrocarbons, alcohols, ketones and so forth. It is a solvent for cellulose esters, "Cumar , copal, gum esters, etc. It is able, when mixed with an alcohol, to dissolve shelloc and alkyd resin. It Is a less odoriferous and mare energetic solvent than amyl acetate. It also has bath a lower boiling point and a greater speed of evaporation. n-Butyl acetate and amyl formate have similar volatility and have substantially the same solvent power which permit free interchange of these only as far as these properties allow. 

Formation of Acetals. The reagent can be used to prepare a variety of acetals via transacetalization. This involves interchanging... 

Dioxolane formation is not limited to aldehydes and ketones. Amide acetals have been prepared directly and by the alcohol interchange method (eq 15). ... 

Detailed kinetic studies and kinetic simulations for the formation and decay of complexes that can only occur by radical interchange were analyzed to give a radical exchange constant (k f) for the vinyl acetate and methyl acrylate polymerizations in the presence of (TMP)Co-P. The rate constants deduced for radical exchange (kex(333 K) = 0.5-1.0 x 10 s ) (P + (TMP)Co-Pn Pm-Co(TMP) + Pn )... 

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