Question

Need help interpreting H NMR? believe it’s cycloheptanone

dovblet) (Tns) 2.5 2.0 1.5 1.0 0.5 0.0 ppm 1.00

Answer 1

Yes it is related to cycloheptanon. In cycloheptanon three type of hydrogen atoms are present which can give total three signals in NMR spectrum. As shown in the theoretical spectrum given below (found by using software) that four protons "a" are just near carbony group give a signal at downfield (higher ppm level = 2.5) due to deshielding of the protons by electronegativity of carbony group. Here these "a" protons are present just nearby protons "b" and no. of "b" protons at a side are two so the signal of "a" protons is splitted into three (triplet is obtained). Now for protons "b" a signal will be obtained at comparetively lower ppm level = 1.7ppm due its low deshielding by carbonyl group. it should be divided into multiplet due to two "a" and two "c" protons at a side as shown in theoretical nmr. But in the practical NMR only one peak is obtained and the splitting is not clear. further for protons "c" one signal will be obtained which is splitted into multiplet (as in standard) but in case of practically obtained only one peak is obtaoned. So overall peaks obtained at 1.6-1.8 ppm are not doublet in the your practical data but these are two separate signal of two different type of protons. Beacuse of very close chemical shift values of "b" and "c" these are looking as doublet.

1.76 2.43 1.60 1.60 2.43 1.76 РРМ