THE MECHANISM OF THE ACETAL REACTION. THE EXPLOSIVE REARRANGEMENT OF HYDROXY-ETHYL VINYL ETHER INTO ETHYLIDENE GLYCOL¹

Abstract

might be reduced by 1000-3000 cal. at room temperature, making it approximately 28,000-30,000 cal. as compared to the above average of -34,200 cal., which also is for room temperature. It is difficult to estimate the accuracy of our results. The most serious source of error is indicated by the presence of considerable amounts of methane among the products of some of the experiments. The corresponding side reaction undoubtedly has displaced equilibrium to some extent. However, in view of the facts that approximately the same endpoint is reached from either side and that our calculated heat of reaction is not unreasonable, we are inclined to believe that our data are not greatly in error. SummaryThe position of equilibrium in the reaction C2H,:~^^~.C2H4 + H2 has been measured at 600, 650 and 700°. Equilibrium was approached from both sides. Some uncertainty exists owing to the simultaneous formation of methane, but the indications are that the equilibrium constants at the three temperatures are 0.0310, 0.082 and 0.20, respectively, partial pressures being expressed in atmospheres.

Regioselective Lithium–Iodine Exchange-Initiated Cleavage of 2-Iodomethyl-1,3-dioxanes: A Complex-Induced Proximity Effect

“…Fragmentation of the Organolithium Derived from 2-(Iodomethyl)-4,4-dimethyl-1,3-dioxane (2). A solution of 0.13 g (0.50 mmol) of 2 in 10 mL of either dry n-pentane, diethyl ether, or tetrahydrofuran was cooled to −70 °C under an atmosphere of argon, and either 2.2 molar equiv of t-BuLi in pentane or 1.0 molar equiv of n-BuLi in heptane was added.…”

“…The fragmentation of β-halo acetals upon treatment with sodium metal was discovered by Wislicenus in the late 1870s, and the cleavage of 2-bromomethyl-1,3-dioxolane under similar conditions was reported by Hill and Pidgeon in 1928 (Scheme ). Swallen and Boord generalized such reactions using zinc metal to provide olefinic hydrocarbons by the elimination of alkoxide and halogen from β-halo ethers. This reaction, known today as the Boord reaction, can be accomplished with zinc, magnesium, sodium, and lithium as well as a variety of other reagents .…”

Vinyl Ethers of Diethylene Glycol

“…Vinyl ethers of glycols undergo the typical reactions of alkyl vinyl ethers. Hill and Pidgeon (6) characterized vinyloxyethanol by hydrolysis, bromine addition, evolution of hydrogen by reaction with sodium, and esterification to a monobenzoate. In the case of monovinyl ether of diethylene glycol, acid catalysis produces a polymeric acetal or the cyclic acetal, 2-methyl-l,3,6-trioxocane, reported by Hurd and Botteron (7) which itself on standing about 2 months polymerized to the polyacetal.…”

“…Assuming the recycle monomer recovered from the reactor product stream bydevolatilization represents the average concentration of mono- (3). 6 Plus 50 parts Phiblack 0 carbon black per TOO parts crude. c Sample 94% soluble in Decalin at T20°C.…”

“…Monovinyl ether of ethylene glycol was first reported by Hill and Pidgeon (6), and using the vinylation reaction, later by Reppe , who also reported the divinyl ether and synthesized the vinyl ethers of 1,4-butanediol and diethylene glycol. Isomerization of vinyloxyethanol to methyldioxolane (Equation 2) /O-CH2 CH2=CHOCH2CH2OH-> CHsCH | (2) \o-CH2 was found by these authors to occur in the presence of acidic substances with explosive violence and also occurred during vinylation and distillation.…”