CHMB42H3 Lecture Notes - Lecture 1: Infrared Spectroscopy, Mass Spectrometry, Mass Spectrum
Document Summary
The mass spectrum - fragmentation fragment ion peak: a positively charged fragment of the molecular ion. Factors influencing carbocation stability hybridization of carbon: increasing s character prefers a negative charge since it is more electronegative. Methyl groups attached to cation: increases electron density through hyperconjugation and stabilizes the cation order of stability, tertiary > secondary > primary > methyl resonance structures, can share charge over more atoms and stabilizes the charge. Most of the common elements found in organic compounds have naturally occurring isotopes which are heavier: m+1 elements: M+1 peak: due to presence of c-13 isotope relative abundance of 1. 11% We know the relative measurement of m+1 to m and thus can calculate the number of carbons in the molecule. Br bond: intensity of m+2 to m peak: one br atom present (79:81 = 1:1) Mass spectrum of chloro containing alkyl halides. Mass spectrum of chloro- containing alkyl halides.
