Lab7 - L ab # 7 Preparation of Cyclohexene by the E1...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Lab # 7 Preparation of Cyclohexene by the E1 Dehydration of Cyclohexanol Chen Zhou (4857694) Partner: Haotian Wu Demonstrator: Craig Mckay March 12 th , 2008 Purpose: -To perform the dehydration of cyclohexanol under first order conditions to obtain cyclohexene. -To study some properties and compare properties and compare the behaviour of alkanes and alkenes to ward several common acidic oxidizing reagents. Introduction: Dehydration processes can be carried out through E1 and E2 reactions. E1 is a unimolecular reaction, which the rate determining step is the departure of the leaving group, resulting the formation of carbocation. The nucleophile in this reaction is the pair of electrons C- H bond adjacent to the carbocation, as the pair of electron is donated to the carbocation, a pi bond (double bond) is formed. Like S N 1 reactions, the rate of reaction is dependant on solvent, substrate concentration and the leaving group. For solvent, E1 reaction works best in polar, and protic solvents, where the solvent can stabilize the carbocation, and form hydrogen bond with the leaving group as well. The substrate concentration is directly proportional to the rate of formation of product. The leaving group, similar to S N 1 must be good for the reaction to proceed. Conversion of poor leaving group can be done through simple protonation from a strong mineral acid, or by the formation of a sulfonate ester. On the other hand, the E2 reaction is bimolecular and it is a concerted process. Like S N 2 reactions, the leaving group leaves simultaneously as the nucleophile attacks the alpha carbon, making its rate depend on both the concentration of the leaving group, as well as the nucleophile. Another major difference between E1 and E2 reaction is that E1 reaction often forms impurities
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
as its reaction is accompanied by elimination reaction. E2 reaction on the other hand, can also generate mixtures, but its proportion can be easily controlled. In this experiment, cyclohexanol will be converted into cyclohexene, and the following are taken into consideration: 1) Upon dehydration, cyclohexanol can give only one alkene. This will prevent the formation of a mixture of very similar products, which the separation would be difficult. For example, if 2-hexanol is used of cyclohexanol, two products would be formed: 2-
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/30/2011 for the course CHEM 1321 taught by Professor Rashmi during the Spring '10 term at Carleton CA.

Page1 / 7

Lab7 - L ab # 7 Preparation of Cyclohexene by the E1...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online