E1 mechanism

Problem # 1281

Allylic and benzylic halides tend to undergo both SN1 and SN2 substitution reactions at a faster rate than their alkyl counterparts.

For example, both allyl chloride and benzyl chloride undergo SN2 reaction at a faster rate than propyl chloride. 

The same holds true for SN1 reactions: a 2° allyl or benzyl halide undergoes SN1 reaction faster than a 2° alkyl halide. Explain.

MS 907 - Alkene Addition and Elimination Mechanisms Submitted by Matt on August 6, 2011.

Textbook and Chapter: Carey and Giuliano 8th Ed. (2010), Chapter 6

Keywords: alkene addition, carbocation, dehydration, E1 mechanism

Description: This mendel set is a complement to Carbocation Drills. It is meant to prepare students on how to approach longer and more complicated mechanisms. Reaction mechanisms covered:

  • Acid-catalyzed elimination (dehydration, E1)
  • Acid-catalyzed addition to an alkene
  • Halohydrin formation (halonium ions, which result in anti-additions.)

Total Problems: 4

Problem # 519

Let's work through an elimination reaction. Draw the structures for each of the species in the three boxes below (protonated thiol, carbocation, and alkene). Also draw curved arrows to show electron movement. 

Problem # 348

For the reaction below, draw the structures of the carbocation intermediate and the final product.

Problem # 341

 Predict the product(s) of the reaction below, and used curved arrows to show a mechanism.

Problem # 335

Carbocations aren't very stable and so don't last very long after they are formed.

Use curved arrows to show:

a) how a carbocation reacts with a halide ions to form an alkyl halide.

b) how a carbocation reacts with water to form an alcohol.

c) how a carbocation reacts with a base to form an alkene.