Combination Tables

Abstract

AssignmentRangeCommentsCH3CH2CHC5--35{\thinspace}ppm5--45{\thinspace}ppm25--60{\thinspace}ppm30--60{\thinspace}ppmCH3, CH2, CH, and C can be differentiated by multipulse experiments (DEPT, APT), off-resonance decoupling, 2D CH correlation spectra, or based on relaxation timesLower shift values in three-membered ringsCH3CH2CH0.8--1.2{\thinspace}ppm1.1--1.8{\thinspace}ppm1.1--1.8{\thinspace}ppmLower shift values in three-membered ringsCH st3000--2840{\thinspace}cm-1Higher frequency in three-membered ringsCH3 $δ$ as≈1460{\thinspace}cm-1CH2 $δ$≈1460{\thinspace}cm-1CH3 $δ$ sy≈1380{\thinspace}cm-1Doublet for geminal methyl groupsCH2 $γ$770--720 cm-1In C--(CH2)n--C with n ≥ 4{\thinspace}at ca. 720 ;cm-1Molecular ionm/z 14n + 2Weak in n-alkanesVery weak in isoalkanesFragmentsn-Alkanes: local maxima at 14n + 1, intensity variations: smooth, minimum at [M-15]+Isoalkanes: local maxima at 14n + 1, intensity distribution: irregular (relative maxima due to fragmentation at branching points with charge retention at the most highly substituted C)Rearrangementsm/z 14 nm/z 14n - 2n-Alkanes: unspecificIsoalkanes: elimination of alkenesMonocycloalkanes: elimination of alkanesNo absorption above 200 nm