Question

11 Spectrum C 10 solvent: CDCI aldol addition (2-acetylpyridine & 4-nitrobenzaldehyde) 9 1.00 2.04 1.12 8.700 8.684 -8.263 8.236 8.207 -8.099 - 8.073 -7.931 -7.926 -7.906 7.900 7.880 -7.875 7.648 7.619 7.565 7.561 7.549 -7.545 -7.540 -7.536 7.524 7.520 5.410 5.398 -5.384 5.370 5.359 4.715 4.703 3.688 -3.677 3.632 3.621 3.602 3.574 3.546 L3.518 1.01 1.02 2 i Activity 10 ppm

the following is spectrum of the reaction if the 2 drawn molecules. are there any peaks in either spectra that show peaks of the starting material. i have circled the diagnostic peaks i am looking for

Answer 1

Sol:

To diagonise the circled protons we have to keep in ind the ¹H-NMR range for two kind of protons that areas follows:

1. Aldehydic proton
2. Methyl proton attached to the keto group

¹H-NMR range for them are as follows:

1. For aldehydic proton: 9.0-10.0 ppm.
2. For methyl proton attached to keto group 2.1-2.4 ppm.

​​​​​​​There is no any peak in this range in both the given spectra , but Spectrum-D will be more appropiate as the 2-3 ppm region is clean, which is not in the case of Spectrum-C.

Sol: Reaction: Alhdol comdensationm Reactants 4-nitnobmzaldehyde, 2-acetylpynidine Diugristic peak t Alelehyolic pro ton , H-NMR nange q.o-10Q ppn 7As the vabolehydle hydregen es shitted far voloonfchl due to onisofno py of the carlomyl group (c o) Thene is no buch peak found in the ven pectrur.

Sol: Methyl prnoton voetached to keto gnnyp R the canbom next to the canbmyl 1 Hydlrogens on gnoup appear in the haane 21 to 24 pm 7Thure is no such peak in that homge fr the given Spectrum Thus. fasing upom this oksorvatiom it cam oe comclnced that tme reaction is completed omd neactants cmverted into pneduct omd there es no neactant in the Heaction qixture