Structure:
IUPAC Name: 3,3-dimethyl-1-butene
Analysis: C6H12: MW = 84.16
IH NMR
The proton NMR has a singlet representing nine equivalent hydrogens (three -CH3 groups) and two highly split multiplets in the region
5 - 6 (the alkene region). The singlet strongly suggests the presence of a tert-butyl group (-C(CH3)3), while the multiplets suggest a terminal alkene ABC splitting pattern.
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C13 NMR
13C NMR Assignments:
C-13 NMR: q-30.6; s-45.2; d-149.3; t-108.5
The 13C spectrum contains four peaks; a quartet at
31, a weak singlet at 45, a doublet at 149 and a triplet at 108. The quartet most likely represents a relatively simple methyl group, bonded to a carbon, and the singlet most likely represents a carbon with no hydrogens, bonded to a mildly electronegative group. The doublet and triplet are in the alkene region; the triplet is somewhat shielded, perhaps due to a steric effect in the ©-position.
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MASS SPECTRUM
Mass Spectrum Fragments:
The mass spectrum consists of a molecular ion at 84, and a base peak at m-15 (m/e = 69) which is consistent with loss of a CH3 group. The spectrum is consistent with a simple molecule which can lose a methyl group to form a stable radical cation.
IR
3400-3200 cm-1: no OH peak 3100 cm-1: sharp peak, suggesting unsaturated CH 2900 cm-1: strong peak suggesting saturated CH 2200 cm-1: no unsymmetrical triple bonds 1750 cm-1: no carbonyl 1650 cm-1: strong peak, suggesting a carbon-carbon double bond
