this question is organic chemistry question Discuss the frag

this question is organic chemistry question

Discuss the fragmentation, which may have led to the peaks indicated in the mass spectrum of 2,2,4-trimethylpentane (see below), and explain why you think there is no molecular ion present. (hint count the number of ways the molecular ion can fragment to give an ion with m/z-99) 2,2,4-trimethylpentane iso-Octane There are no peaks above mlz. 100 30 m/z 57 Molecular weight 114 m/z.99 20 70 80 90 1o0 40 50 6o 20 30 10 m/z

Solution

Organic chemistry

Fragmentation pattern in the mass spectrum of 2,2,4-trimethylpentane

First the molecule looses a -CH3 to give a peak m/z 99

This is a readily lost fragment (-CH3) and therefore we do not see a molecular ion in the mass spectrum of this molecule.

Loss of the entire (CH3)2CHCH2- unit gives a tertiary butyl fragment which is very stable and gives base peak m/z 57.The lost unit has a mass at m/z 43.

loss of CH3 from base peak gives m/z 41.