2738-19-4Relevant articles and documents
Directing the Rate-Enhancement for Hydronium Ion Catalyzed Dehydration via Organization of Alkanols in Nanoscopic Confinements
Shetty, Manish,Wang, Huamin,Chen, Feng,Jaegers, Nicholas,Liu, Yue,Camaioni, Donald M.,Gutiérrez, Oliver Y.,Lercher, Johannes A.
, p. 2304 - 2311 (2021)
Alkanol dehydration rates catalyzed by hydronium ions are enhanced by the dimensions of steric confinements of zeolite pores as well as by intraporous intermolecular interactions with other alkanols. The higher rates with zeolite MFI having pores smaller than those of zeolite BEA for dehydration of secondary alkanols, 3-heptanol and 2-methyl-3-hexanol, is caused by the lower activation enthalpy in the tighter confinements of MFI that offsets a less positive activation entropy. The higher activity in BEA than in MFI for dehydration of a tertiary alkanol, 2-methyl-2-hexanol, is primarily attributed to the reduction of the activation enthalpy by stabilizing intraporous interactions of the Cβ-H transition state with surrounding alcohol molecules. Overall, we show that the positive impact of zeolite confinements results from the stabilization of transition state provided by the confinement and intermolecular interaction of alkanols with the transition state, which is impacted by both the size of confinements and the structure of alkanols in the E1 pathway of dehydration.
1,1,2,2-Tetrafluoroethyl-N,N-dimethylamine: A new selective fluorinating agent
Petrov,Swearingen,Hong,Chris Petersen
, p. 25 - 31 (2007/10/03)
The title compound has been prepared in 96-98% yield by the reaction of tetrafluoroethylene and dimethylamine. 1,1,2,2-Tetrafluoroethyl-N,N-dimethylamine (1) is found to be an effective reagent for the conversion of alcohols into alkyl fluorides. Reaction of 1 and primary alcohols proceeds with high yield formation of the corresponding alkyl fluorides at elevated temperature. However, the reaction of secondary and tertiary alcohols rapidly takes place at 0-10°C, producing corresponding alkyl fluorides as major product along with some olefins.
Correlation of Alkyl and Polar Substituents at the Alcoholic Side of Tertiary Acetates with the Rate of Pyrolyses in the Gas Phase
Gonzalez, Neil,Martin, Ignacio,Chuchani, Gabriel
, p. 1314 - 1318 (2007/10/02)
The rate coefficients for the gas-phase pyrolysis of several tertiary acetates have been measured in a static system over the temperature range of 220-340 deg C and pressure range of 40-186 torr.In seasoned vessels the reactions are homogeneous, follow a first-order rate law, and are unimolecular.The temperature dependence of the rate coefficients is given by the following Arrhenius equations: for 3,3,3-trichloro-2-methyl-2-propyl acetate, log k1 (s-1) = (13.86 +/- 0.35) - (188.8 +/- 3.8) kJ mol-1 (2.303 RT)-1; for methyl α-acetoxyisobutyrate, log k1 (s-1) = (12.42 +/- 0.28) - (174.6 +/- 3.2) kJ mol-1 (2.303 RT)-1; for 2-methyl-2-hexyl acetate, log k1 (s-1) = (13.35 +/- 0.33) - (166.1 +/- 3.4) kJ mol-1 (2.303 RT)-1; for 2,4-dimethyl-2-pentyl acetate, log k1 (s-1) = (12.42 +/- 0.19) - (154.1 +/- 1.9) kJ mol-1 (2.303 RT)-1; for 2-methyl-2-acetoxy-4-phenylbutane, log k1 (s-1) = (11.97 +/- 0.55) - (151.5 +/-5.6) kJ mol-1 (2.303 RT)-1.The effectof substituents in the gas-phase elimination of 2-substituted 2-propyl acetates may be either electronic or steric in nature.The linear correlations for electron-releasing groups and for electron-withdrawing groups are presented and discussed.The results of the present work together with those reported in the literature lead to the establishment of a possible generalization on the influence of substituents at the alcohols side of primary, secondary, and tertiary acetates pyrolyses in the gas phase.
