947-40-0Relevant academic research and scientific papers
A new and more efficient synthesis of methylene acetals
Chu, Guobiao,Zhang, Yanqiao,Li, Chunbao,Zhang, Yuqing
experimental part, p. 3828 - 3832 (2010/03/03)
A new and efficient synthesis of benzyl chlorides and methylene acetals by use of 2,4-dichloro-6-methoxy[l,3,5]triazine (MeOTCT) and dimethyl sulfoxide has been developed. Chlorides are the major products for benzyl alcohols, while methylene acetals are the major products for secondary alcohols. This procedure provides the highest yields so far for methylene acetals of steroids. A plausible mechanism is proposed on the basis of the experiments. Georg Thieme Verlag Stuttgart.
An efficient method for chlorination of alcohols using PPh3/Cl3CCONH2
Pluempanupat, Wanchai,Chavasiri, Warinthorn
, p. 6821 - 6823 (2007/10/03)
A new and convenient method for the chlorination of alcohols utilizing PPh3/Cl3CCONH2 is addressed. Various alcohols could smoothly be converted into their corresponding alkyl chlorides in high yield under mild conditions with short reaction times. A mechanism is disclosed with the evidence of inversion of configuration of the analogous alkyl chloride derived from R-(-)-2-octanol.
Non-linearity and non-additivity of substituent effects in solvolysis of 1,1-diphenylethyl p-nitrobenzoates
Uddin, Md. Khabir,Fujio, Mizue,Kim, Hyun-Joong,Rappoport, Zvi,Tsuno, Yuho
, p. 1371 - 1379 (2007/10/03)
The solvolysis rates of 1,1-diarylethyl p-nitrobenzoates and chlorides Y-Ar(X-Ar)CMe-LG (LG = OPNB, Cl) have been determined conductimetrically at 25°C in 80% (v/v) aqueous acetone. A linear Yukawa-Tsuno (Y-T) correlation was found for the symmetrical subseries (X = Y), showing a precise additivity relationship for the whole substituent range with ρsym = -3.78 and rsym = 0.77. The unsymmetrical subsets (X ≠ Y) gave statistically less reliable Y-T correlations, the apparent p value decreasing significantly when the fixed substituent Y becomes more electron-donating, which is in line with expectations from the Reactivity-Selectivity Relationship. In the whole dispersion pattern, both strong p-π-donor and electron-withdrawing substituents in any fixed-Y subsets exhibit significant rate-enhancement deviations from the points of X = Y on the reference ρsym line, which suggests an anti-Hammond shift of the transition state. However, there was a precise Extended Bronsted Linear Relationship between the pKR+ values for the hydration of 1,1-diarylethylenes and the rates of solvolysis of the p-nitrobenzoates with a slope of unity (α = 1.03). This is direct, convincing evidence that there is no significant shift of the transition-state coordinate over the whole range of substituent change.
The Reaction between Acyl Halides and Alcohols: Alkyl Halide vs. Ester Formation
Strazzolini, Paolo,Giumanini, Angelo G.,Verardo, Giancarlo
, p. 217 - 254 (2007/10/02)
In the reaction between an acyl halide and an alcohol the thermodynamically favoured products are the free carboxylic acid and the alkyl halide.The initial reaction is, generally, the formation of an ester and HHal.When the alcohol is very prone to yield an alkyl cation upon protonation by HHal, formed H2O exhibited a superior reactivity and competed successfully with the alcohol for the acyl halide making, therefore, ester formation practically confined to a triggering role.But, in those cases where the cation is less easily formed, ester formation was favoured and, consequently, became the necessary elementary step towards alkyl halide formation.Tis final product, on the other hand, might be extremely slow to form in an SN2 reaction between the protonated ester function and the halide ion.In these instances, therefore, as well as in the cases when a basic solvent competes for the proton of HHal, the ester is the final product.A notable exception of the situation above outlined, is given by α-hydroxy-α-phenylbenzeneacetic acid (2y), which appears to undergo direct chlorine-hydroxyl interchange through a quaternary intermediate (E), in the end collapsing to α-chloro-α-phenyl-benzeneacetic acid (4y).Different systems were compared using CH2Cl2 as a solvent under strictly similar conditions.Some 28 different substrates were tested for reaction with AcCl (1a), whereas the action of eight acyl halides (a) against (RS)-α-methylbenzenemethanol (2n) and α-phenylbenzenemethanol (2p), as well as the effect of five different solvents on the reaction between two alcohols (2p and 2-methyl-2-propanol, 2c) with 1a, were observed.
Kinetic deuterium isotope effects as evidence for a common ion-pair intermediate in solvolytic elimination and substitution reactions of 1,1-diphenylethyl chloride
Thibblin, Alf,Sidhu, Harvinder
, p. 7403 - 7407 (2007/10/02)
Solvolysis of 1,1-diphenyl-1-chloroethane (1-Cl) in acetonitrile at 25°C provides the elimination product 1,1-diphenylethene (3). Addition of water or methanol to the acetonitrile increases the rate of elimination and gives rise to a second product, 1,1-diphenyl-l-hydroxyethane (1-OH) or 1,1-diphenyl-l-methoxyethane (1-OMe). The deuteriated analogue, 1,1- diphenyl-l-chloro[2,2,2-2H3]ethane (d-1-Cl), reacts slower. The overall kinetic deuterium isotope effect was found to decrease from (k12H + k13H)/(k12D + k13D) = 1.73 in pure acetonitrile to 1.34 in 20 vol % methanol in acetonitrile. This isotope effect is composed of a substitution isotope effect k12H/k12D and an elimination isotope effect k13H/k13D, which simultaneously change from 0.84 to 0.96 and from 2.2 to 3.2, respectively, when the methanol concentration is increased from 1.96 to 9.09 vol %. These results indicate a branched mechanism involving an almost rate-limiting formation of a common carbocationic intermediate. The acid-catalyzed solvolysis of 1,1-diphenyl-l-phenoxyethane (1-OPh) in acetonitrile containing 0.4 vol % aqueous 2 M sulfuric acid quickly provides the alcohol 1-OH, k12/k13 ≈ 11, which in a subsequent fast reaction yields the olefin 3 as the final product. In contrast, the solvolysis of the chloride 1-Cl in 0.4 vol % water in acetonitrile yields almost exclusively olefin 3, k12/k12 = 0.003. The results strongly indicate that the leaving chloride anion is involved in the elimination process and that the common intermediate is the contact ion pair. The isotope effect of the acid-catalyzed elimination of the alcohol 1-OH in 0.4 vol % water in acetonitrile is k13H/k13D = 5.3, which increases to k13H/k13D = 6.5 in 25 vol % acetonitrile in water. The possibility of an ion-molecule pair intermediate in the acid-catalyzed solvolysis is discussed.
