Catalytic conversion of alcohols: The impact of inductive effect for secondary alcohol dehydration

Dabbagh, Hossein A.

doi:10.1016/0021-9517(88)90334-x

Cited by 11 publications

(4 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both homogeneous and heterogeneous dehydration of secondary and tertiary alcohols are among the most studied of all major organic processes. − There have been a number of attempts to relate the mechanisms of these two systems; many discrepancies, however, have resulted from the different reaction conditions and reagents used (Tables and ).…”

Section: Discussionmentioning

confidence: 99%

“…Metal oxides are excellent and widely used catalysts for the dehydration of alcohols. − ,− It has been shown that many discrepancies can result from different catalytic properties of the aluminum oxide and thorium oxide catalysts used in different laboratories and/or from different reaction conditions. These catalysts can vary widely in their activity for skeletal isomerization and for double-bond shift of olefinic hydrocarbons.…”

Section: Introductionmentioning

confidence: 99%

“…Stereochemistry of elimination (anti or syn) in concerted homogeneous reactions depends on the properties of the system and mainly upon those of the substrate and the steric interactions of the intermediates and/or the transition states . Anti elimination occurs from gauche conformations of the molecule and syn elimination from eclipsed conformations. ,,,− …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

New Transition-State Models and Kinetics of Elimination Reactions of Tertiary Alcohols over Aluminum Oxide

Dabbagh

Salehi

1998

J. Org. Chem.

View full text Add to dashboard Cite

A new transition-state model was developed in order to justify the anti intramolecular E2 elimination with cis (Z)-preference over pure alumina and intermolecular E2 elimination with trans (E)-preference over doped alumina. The reactions of model compounds 1,2,3-triphenyl-2-propanol (1), 1,2-diphenyl-2-propanol (2), and 3,3,3-trideuterio-1,2-diphenyl-2-propanol (3) with aluminum oxides with a pH range of 4.5−9.5 and thorium oxide in the temperature range of 200−350 °C in 2-hexanol have been investigated. Over acidic alumina (pH = 4.5 ± 0.5), the ratio of E-isomer to Z-isomer (E/Z ≅ 2) for 2 was found to remain unchanged in this temperature range. At 300 °C, however, Saytzeff elimination favored Hofmann. Over pure alumina the E/Z ratio was equal to 0.650 (2-alkene/1-alkene = 0.750). At equilibrium, the E/Z ratio for 2 was equal to 4.5 with the formation of trace amounts of Hofmann adducts. The ratio of Saytzeff to Hofmann elimination was found to be pH independent. Any decrease in pH caused a slight increase in the E/Z ratio. The average primary kinetic isotope effect (k H/k D) for elimination at 230 °C was equal to 3.775 ± 0.227. The ratio of E/Z over thorium oxide at 300 and 350 °C was similar to that of aluminum oxide at 300 °C, but the Saytzeff elimination was surprisingly favored over Hofmann! The energy of activation (E a), entropy of activation (ΔS ⧧), selectivity, isotope effect (k H/k D), and semiempirical calculation (AM1) all agreed with concerted E2 elimination.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

New Transition-State Models and Kinetics of Elimination Reactions of Tertiary Alcohols over Aluminum Oxide

Dabbagh

Salehi

1998

J. Org. Chem.

View full text Add to dashboard Cite

show abstract

“…In secondary alcohols the overall activity of the various metal oxides for dehydration has been found as a function of the acidity strength [16][17][18], while the selectivity has been related to the density of acid sites [19]. In our supports we assume that indium was incorporated in the alumina gel decreasing the number of Al 3+ in pentahedral coordination, and hence, as is shown in Table 2, a diminution in the overall dehydration activity must be obtained.…”

Section: Fig 3 Xrd Patterns For Indium-doped Alumina Sol-gel Preparmentioning

confidence: 99%

Sol-gel preparation of In2O3-Al2O3 supports with controlled textural and structural properties

Rodríguez-González

Gómez

Moscosa-Santillán

et al. 2007

React Kinet Catal Lett

View full text Add to dashboard Cite

Alumina supports with a very narrow pore size distribution were obtained with indium-doped alumina prepared by the sol-gel method. The formation of aluminum in pentahedral coordination was identified by 27 Al NMR-MASspectroscopy. A good correlation was obtained with the Al V NMR-MAS intensity signal and the activity in isopropanol dehydration. The insertion of In 3+ substituting some Al 3+ in the alumina network was suggested.

show abstract

Pentanols

Lappe¹,

Hofmann²

2000

Ullmann's Encyclopedia of Industrial Chemistry

View full text Add to dashboard Cite

Catalytic conversion of alcohols: The impact of inductive effect for secondary alcohol dehydration

Cited by 11 publications

References 11 publications

New Transition-State Models and Kinetics of Elimination Reactions of Tertiary Alcohols over Aluminum Oxide

New Transition-State Models and Kinetics of Elimination Reactions of Tertiary Alcohols over Aluminum Oxide

Sol-gel preparation of In2O3-Al2O3 supports with controlled textural and structural properties

Pentanols

Contact Info

Product

Resources

About