Image's source: chemhelper

Electrophilic Addition

 

This mechanism takes place in alkenes.

Instructions: Follow the links (underlined sentences) below to understand the electrophilic addition mechanism.

Links:

1. What is electrophilic addition?

2. The reaction with bromine... (Addition of bromine to a carbon-carbon double bond).

     i. Explanation

    ii  Explanation 2

    ii. 2D animation (ethene and bromine)

    iii. Animated mechanism(1) or (2) 

    iv. Reaction of unsymmetrical alkene with bromine (please refer to 3 (ii)(d)) below.

    v. Comparison of addition in ethene and propene (primary and secondary   carbocations).

    vi. Formation of 2-bromoethanol from ethene and bromine water.

3. The reaction with hydrogen halide... (Addition of hydrogen bromide)

    i. Reation of symmetrical alkene: Explanation   and More detailed explanation.

   ii. Reaction of unsymmetrical alkene (Markovnikov addition)

       Eg.: The reaction between propene and hydrogen bromide in the gas phase:

CH3CH=CH2 + HBr  CH3CH2BrCH3

   ii(a). Carbocations (carbonium ions) and their stability... (Essential pre-reading before you tackle anything else in this section.)

    ii(b). Why unsymmetric alkenes are a problem ... (Explains the reasons behind Markovnikov's Rule, and gives a general mechanism for these more awkward reactions. This is also essential reading before you look at specific reactions.)

   ii(c). Reaction between Propene and HBr (Explanation) More details &

           Animated mechanism & 2D Animation

   ii(d). Reaction between Propene and Bromine and More details.

4. Electrophilic addition: audio tutorial

How and why are bromine molecules attracted to ethene? Jenny Wells explains to help you understand the mechanism of electrophilic addition. Download the audio file on the link above.

Download the script here Electrophilic Addition Audio Tutorial Script

5.  Movie on the mechanism (if you can't see the movie here, try click at the movie file below.)

Mechanism Movies.mov Mechanism Movies.mov
Size : 0.583 Kb
Type : mov
Organic Chemistry  HX to Alkene Reaction.flv Organic Chemistry HX to Alkene Reaction.flv
Size : 4.819 Kb
Type : flv
 
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