Group Frequencies of the Hydrocarbons

Alkanes. The C—H vibrational modes of the alkanes (or mixed compounds containing alkyl groups) that are characteristic and reliable group frequencies are summarized in Table 8.1 (also see Chapter 8W, IR section. Part 11 A). 

Alkenes C=C Stretching. It is possible to classify open-chain unsaturated systems into two groups, those with C=C stretching modes falling above 1660 cm and those with modes falling below 1660 cm as shown in fwww]h Table 8.2 (see also Chapter 8W, IR section, Fhrt II Bl). 

Alkenes C—H. Several fundamental modes associated with the alkene 

Alkynes. The group frequencies of the alkynes are summarized in Table 8.4 [www - (sss 1 0 Chapter 8W, IR section, Part II C). 

The wavenumber values for the all-in-phase C—H bending vibrations are presented in Table 8.5. 

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