How many peaks would you expect in the 1H NMR spectrum of 1, 4-dimethyl-benzene para-xy1ene or p-xylene)? What ratio of peak areas would you expect on integration of the spectrum? Refer to Table 13.3 for approximate chemical shifts, and sketch what the spectrum would look like. (Remember from Section 2.4 that aromatic rings have two resonanceforms.)

Transcribed Image Text:

Correlation of 'H Chemical Shift with Environment Table 13.3 Type of hydrogen Chemical shift (8) Chemical shift (8) Type of hydrogen Si(CH3)4 Reference —С -о—н Alcohol 2.5-5.0 -CH3 Alkyl (primary) 0.7-1,3 -CH2- Alkyl (secondary) 1.2-1.6 for H. 3.3-4.5 -CH- Alcohol, ether Alkyl (tertiary) 1.4-1.8 C=C-C- Allylic 1.6-2.2 Vinylic 4.5-6.5 Aryl Ar-H -c-CH3 Methyl ketone -CHз 2.0-2.4 Ar-CH3 Aromatic methyl 2.4-2.7 9.7-10.0 Aldehyde C-H 2.5-3.0 Alkynyl -C=C-H С -о—н Carboxylic acid 11.0-12.0 -C-Hal Alkyl halide 2.5-4.0 СНз p-Xylene Нас