Advices For Studying Organic Chemistry

propene, and 2-methylpropene:

Red indicates relatively negative areas and blue indicates relatively positive (or less

negative) areas.

Figure 8.A As alkyl substitution increases, carbon is able to accommodate greater
positive charge and bromine contributes less of its electron density.

1. As alkyl substitution increases in bromonium ions, the carbon having greater

b

2) In the bromonium ion of ethene (I), the bromine atom contributes substantial

electron density.

ositive charge is localized there (as is indicated by deep blue at the

tertiary carbon in the electrostatic potential map).

i

bromine).

4) II), which has a secondary carbon, utilizes some

electron density from the bromine (as indicated by the moderate extent of yellow

substitution requires less stablization by contribution of electron density from

romine.

3) In the bromonium ion of 2-methylpropene (III):

i) The tertiary carbon can accommodate substantial positive charge, and hence

most of the p

i) The bromine retains the bulk of its electron density (as indicated by the

mapping of red color near the

ii) The bromonium ion of 2-methylpropene has essentially the charge distribution

of a tertiary carbocation at its carbon atoms.

The bromonium ion of propene (

near the bromine)