Showing papers on "Methyl vinyl ketone published in 1975"
TL;DR: Comparing biological activities of con jugated carbonyls their reactivity towards HS (k1) and the stability of the adducts must be considered and the equilibrium constants as well as the rate constants for forward and reverse reaction show an extreme variation depending on the carbonyl structure.
Abstract: 1. GSH reacts with conjugated carbonyls according to the equation: GSH+R-CH=CH-COR in equilibrium R-CH(SG)-CH2-COR. The forward reaction follows second order, the reverse reaction first order kinetics. It is assumed that this reaction reflects best the ability of conjugated carbonyls to inactivate SH groups in biological systems. 2. The rate of forward reaction increases with pH approx. parallel with alphaSH. Besides OH- ions also proton donors (e.g. buffers) increase the rate. The catalytic effect of pH and buffer is interpreted in view of the reaction mechanism. 3. The equilibrium constants as well as the rate constants for forward (k1) and reverse reaction show an extreme variation depending on the carbonyl structure. Acrolein and methyl vinyl ketone (k1 = 120 and 32 mol-1 sec-1, resp.) react more rapidly than any other carbonyl to give very stable adducts (half-lives for reverse reaction 4.6 and 60.7 days, resp). Somewhat less reactive are 4-hydroxy-2-alkenals and 4-ketopentenoic acid (k1 between 1 and 3 mol-1 sec-1), but they also form very stable adducts showing half-lives between 3.4 and 19 days. All other carbonyl studied react either very slowly (e.g. citral, ethly crotonate, mesityl oxide, acrylic acid) or form very labile adducts (crotonal, pentenal, hexenal, 3-methyl-butenone). Comparing biological activities of conjugated carbonyls their reactivity towards HS (k1) and the stability of the adducts must be considered.
240 citations
38 citations
TL;DR: 4-Methylcycloph phosphamide cannot form metabolites analogous to 4-ketocyclophosphamide and carboxyphosphamide, the relatively non-toxic metabolites of cyclophosphamia, and the significance of this fact is discussed in relation to a mechanism which could account for the relatively selective cytotoxicity of cyclophile in vivo towards neoplastic tissue.
27 citations
TL;DR: In this paper, the same principle reaction was used for the total synthesis of (±) 2 - (p - chlorophenyl) - 3 - oxa - A - nor - estra - 1,5(10), 9(11) - triene - 17 - acetate 12a.
12 citations
TL;DR: In this article, a new vinyloxyborane derivative, Id, was found to be formed in reaction of phenyl di-n-butylthioboronite (II) with methyl vinyl ketone.
Abstract: A new vinyloxyborane derivative, Id, was found to be formed in reaction of phenyl di-n-butylthioboronite (II) with methyl vinyl ketone. In order to explore its utilization in organic synthesis, the reactivity of Id and other known vinyloxyboranes was variously examined. Id and Ie gave β-hydroxyketones (IVa–c, Va–d) in fairly good yields when they were allowed to react with carbonyl compounds. The reaction of Ia′ and Ib with nitriles, followed by hydrolysis, afforded β-iminothioates (VIa–c) and β-ketoesters (VIIa–d) respectively. It was also found that the borane (Ib) reacted with formates or formamides at room temperature to give ethyl α-formylhexanoate.
8 citations
TL;DR: In this article, photochemical substitution of one carbonyl group of cyclopentadienyl- and methylcyclopentadiylmanganese tricarbonyl was used to synthesize complexes of methyl vinyl ketone, benzylidene acetone and cyclohexenone.
5 citations
4 citations
TL;DR: Their structures and configurations have been elucidated by 1H-NMR and 13C NMR spectroscopy for (Z/E)-2b and (Z)-2d also by conversion into (r-4.6)-trisubstituierte 1.3.
4 citations
TL;DR: In this paper, it was shown that silyl enol ethers react with α,β-unsaturated ketones and esters in the presence of TiCl4 under mild (−78°C) conditions to give 1,5-dicarbonyl compounds in good yields.
Abstract: It was found that silyl enol ethers react with α,β-unsaturated ketones and esters in the presence of TiCl4 under mild (−78°C) conditions to give 1,5-dicarbonyl compounds in good yields. Further, it was also found that 1-phenyl-1,5-hexanedione and its monoacetal were obtained by the TiCl4-promoted reaction of methyl vinyl ketone ethylene acetal with α-trimethylsiloxystyrene.
1 citations
Patent•
07 Oct 1975TL;DR: Methylheptenone is obtained by heating a reaction mixture, which contains 1 part methyl vinyl ketone and 4 to 40 parts isobutylene, in the presence of a strong acid, to a temperature of 260 DEG C. at a pressure at or above the vapor pressure of the reaction mixture as mentioned in this paper.
Abstract: Methylheptenone is obtained by heating a reaction mixture, which contains 1 part methyl vinyl ketone and 4 to 40 parts isobutylene, in the presence of a strong acid, to a temperature of 260 DEG C. to 290 DEG C. at a pressure at or above the vapor pressure of the reaction mixture.
1 citations
TL;DR: In this article, three poly(vinyl ketones) have been partially reduced to obtain different copolymers of vinyl ketones and secondary allyl alcohols and 13C NMR spectroscopy confirmed the existence of ring-chain tautomerism between a carbonyl group and a neighboring hydroxyl group.
Abstract: Three poly(vinyl ketones) have been partially reduced to obtain different copolymers of vinyl ketones and secondary allyl alcohols. The first set of copolymers is obtained by partial reduction of poly(phenyl vinyl ketone). UV studies indicated that the Beer-Lambert law cannot be applied to the different carbonyl bands. This is explained by a ring-chain tautomerism between a carbonyl group and a neighboring hydroxyl group.
IR and 13C NMR spectroscopy confirmed these results and proved the existence of this tautomerism.
The second set of copolymers were obtained by partial reduction of poly(methyl vinyl ketone). UV showed the tautomsrism was strongly shifted toward the ring form; acetal condensation occurs in (tetrahydrofuran) THF-methanol-water mixture solution.
The third set of copolymers obtained by partial reduction of chiral poly [(S-2-methyl-butyl)vinyl ketone] were studied by UV, ORD (optical rotary dispersion), and CD (circular dichroism); all three methods giving concordant results. The tautomerism was shifted more toward the chain form than for the reduced poly(methyl vinyl ketones) but less than for reduced poly(phenyl vinyl ketones).
The addition of strong acid to the polymer solution shifts the equilibrium toward the chain form; a similar shift is observed when the original polymer is in the solid state.