Aliphatic Alkanes, Alkenes, Alkynes, and Alkyl Halides

1 Aliphatic Alkanes, Alkenes, Alkynes, and Alkyl Halides 

Alkenes have two characteristic types of protons. The vinyl protons are those attached to a double bond. Vinyl protons are deshielded by the double bond and generally appear at chemical shifts between 4.5 and 6 ppm. The spin-spin coupling of vinyl protons is complicated because they are generally not chemically equivalent due to the lack of free rotation about the double bond. Allylic protons are those located on carbon atoms adjacent to the double bond these are slightly deshielded by the double bond and appear between 1.2 and 2.5 ppm. The presence of the 

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