Determining structures using mass spectra

Question 1

High resolution mass spectrometry is:

Answer 1

(HRMS) is a type of mass spectrometry that can produce Mr values with several decimal places, usually four or more

Question 2

the two aspects of mass spectrometry (from Book 1) are:

Answer 2

• determining the relative atomic masses of elements from isotopic abundances
• using fragmentation patterns to determine the structures of organic compounds

Question 3

HRMS is used to determine

Answer 3

the molecular formula (although not always the structure or identity)

Question 4

use the data below to find the structure of a compound which was found to have an Mr value of 84.0573
is it:
CH2=CHCH2CH2CH2CH3 or CH3CH=CHCH2CHO

Mr of H: 1.0078
Mr of C: 12.0000
Mr of N: 14.0031
Mr of O: 15.9949

Answer 4

Mr of H: 1.0078
Mr of C: 12.0000
Mr of N: 14.0031
Mr of O: 15.9949

CH2=CHCH2CH2CH2CH3 : (6x12.0000) + 12x1.0078) = 84.0936

CH3CH=CHCH2CHO : (5x12.0000) + (8x1.0078) + 15.0049 = 84.0573

the compound is CH3CH=CHCH2CHO