508. 2-Methylbut-2-ene nitrosochloride and its derivatives

Hydration of 3-methyl-3-buten-2-one (isopropenyl methyl ketone)

“…We conclude that the hydration of isopropenyl methyl ketone occurs in the expected manner, to yield 4-hydroxy-3-methyl-2-butanone (3). It would seem almost certain that this was also the product encountered in the original report,3 since the 2,4-dinitrophenylhydrazone of the product there described had mp 192°, which coincides with that of isopropenyl methyl ketone, and 4-hydroxy-3-methyl-2butanone is known to yield this derivative under the acid conditions normally used for 2,4-dinitrophenylhydrazone formation.7 Further, 3-hydroxy-3-methyl-2-butanone (2) with 2,4-dinitrophenylhydrazine in alcoholic acid media yields not the simple derivative, but that of the 0-alkyl ketone CHgCOjCHs^OR.8 Finally, the p-nitrobenzoates of both isomeric alcohols 2 and 3 were prepared.…”

“…A fraction, bp 86-94°(25-35 mm) (127 g), consisting of 4-hydroxy-3methyl-2-butanone, was collected. It showed a single peak on glc: ir (film) 3425 (OH) and 1709 cm-1 (C=0); nmr 1.09 (d, J = 7 Hz, 3 H, CHCH3), 2.19 (s, 3 H, COCH3), 2.80 (m, 1 H, CH), 3.34 (s, 1 H, OH), and 3.69 ppm (d, J = 7 Hz, 2 H, CH2OH). The 2,4-dinitrophenylhydrazone, prepared under mild conditions in diglyme,7 had mp 108-109°(lit.7 mp 107-109°); under strongly acidic conditions the derivative of isopropenyl methyl ketone was formed7 (see below).…”

“…2 It has been reported that 3-methyl-3-buten-2-one (isopropenyl methyl ketone, 1) behaves abnormally in this reaction, yielding 3-hydroxy-3-methyl-2-butanone (2) instead of the anticipated 4-hydroxy-3-methyl-2-butanone (3). 3 The formation of this unexpected product has been explained in terms of a possible methyl migration in 1 subsequent to protonation,3 or of Markovnikov addition of water to the enolic form of l. Since there appeared to be no compelling reason why 1 should be hydrated in this unusual manner, we have carefully reinvestigated the reaction, and our findings show that in fact the sole product of the addition (aside from polymeric material and unchanged ketone) is the expected 4-hydroxy-3-methyl-2-butanone (3). None of the isomeric ketol 2 could be detected.…”

Atomic oxygen. V. Reactions of enol ethers with oxygen (3P) atoms

“…The reaction of 2,3-dihydrofuran with 0(3P) should proceed in a manner similar to the reaction of cyclopentene, which has been studied extensively by Cvetanovic and coworkers.14 A mechanism for the formation of the observed products is proposed in Scheme III. Scheme III 15 16…”

Oximes: Chemical Properties, Methods of Preparation and Applications in Synthesis of Nitrogen Functional Groups

“…51 Nesta metodologia de obtenção de oximas, a espécie NOX é fundamental, e esta pode ser gerada a partir de nitritos de alquila (RONO) ou ácido nitroso (HONO), em presença de ácido, segundo a seguinte e uaç o: RONO + XH → NOX + ROH. 55,56,57 Esquema 7. Reação de preparação de oximas em carbonos -carbonila (carbonos enolizáveis)…”