Mass Spec

Question 1

What happens in mass spec

Answer 1

Sample molecules are ionised by high energy electrons or small molecules

The mass ti charge ration of the resulting ions is measured very accurately , providing a precise molecular weight.

Ion fragmentation patterns may be related ti the structure of the molecule.

Question 2

Does nmr detect charged or u charged fragments

Answer 2

Charged

Question 3

What is the base peak

Answer 3

The most intense peak that is assigned an Abundance of 100

Question 4

What is the molecular ion

Answer 4

The highest mass ion in a spectrum

Question 5

What are fragment ions

Answer 5

When residual energy from the Collins causes the molecular ion to fragment into neurtral pieces

Question 6

Which type of carbocation are the most stable

Answer 6

Tertiary as due to ch3 symptoms helping eliminate some of the positive charge

Question 7

What way do linear hydrocarbons tend to fragment

Answer 7

They tend to have stronger molecular ions - they don’t tend to breakdown as they can’t break into tertiary carbocation ti gain stability

Question 8

What way do branched hydrocarbons tend to fragment

Answer 8

More likely to fragment as can form tertiary carbocation to gain stability

Question 9

Types of fragmentation that can occur

Answer 9

See notes

Question 10

Hey may the molecular ion not be present in a mass spec

Answer 10

The molecular ion may not be stable