1. STRUCTURAL DETERMINATION MASS SPECTRUM (MS) LAB 12

2. MASS SPECTRUM mass spectrum will usually be presented as a vertical bar graph, in which each bar represents an ion having a specific mass-to- charge ratio (m/z) and the length of the bar indicates the relative abundance of the ion.

3. MASS SPECTRUM Mass Spectrometer: The sample is struck by high-energy electrons, sufficient to make the molecule lose an electron (+ve charge ions). e¯ + M → M ⁺ +2e ¯ The masses of the fragments are measured.

4. Base peak: the most intense peak in the MS, (100% intensity). Molecular ion peak: is the detectable number of molecular ions reach the detector with out fragmenting. (the highest mass in the spectrum) MASS SPECTRUM

5. FRAGMENTATION IN MS 1-alkanes: e.g. hexane

6. 1-alkanes: e.g. hexane Hexane(m/z = 86) FRAGMENTATION IN MS

7. 1-alkanes: e.g. hexane Hexane(m/z = 86) base peak (100%) parent peak or molecular ion (M+)

8. FRAGMENTATION IN MS 2- alcohol e.g. 3-methyl-1-butanol 88=(m\z) M-17: -OH M-18: -H2O

9. Isotope: are different types of atoms of the same element. Each isotope have a different mass number but not atomic number. Most elements occur naturally as a mixture of isotopes. FRAGMENTATION IN MS

10. Isotope: e.g. methylene chloride Cl (³ ⁵ Cl, ³ ⁷ Cl), 3:1 FRAGMENTATION IN MS

11. Thank you