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I need help with these question in the picture. and I also need to find a tutor who can help me understand about spectroscopy, spectrum in organic chemistry

stretches for cyclic by 2050 cm to a oother For each pair of "max mdiane how they 2 Give the structure of the molecule r is consistent with each set of spect data given below. ral a. C, o, 298, 2s60, 1712cm c. C, H O. 3070, 2810.2704, 1705, 1615 cm b HSOC, 2975, 2a64, 1785 cm d. CHAO, 3070.2983, 2846, 1761. 1640 cm prace the following rypes of non jugated carbonyl into ascending order of frequency. akiehyde, acid anhydride, esrer, carboxylic acid, amide, acid chloride

Explanation / Answer

A. Benzoic acid carbonyl streatching freq. is around 1690cm-1 and formic acid has around 1720cm-1. The benzene ring conjugation with carbonyl C=O increases the charge separation and hence it lowers down the wavenumber.

B. But-3-en-2-one has carbonyl streatching freq. around 1690cm-1 and acetone has around 1715cm-1. The but-3-en-2-one has double bond in conjugation with carbonyl C=O, hence it has lowered the wavenumber of the streatching freq as compared to acetone.

C. Amide group lowers the frequency due to its resonance effect. When nitrogen is attached to the carbonyl carbon then the lone pair of electrons on nitrogen can stabilize the resonance form. Due to this lower energy resonance form the carbonyl carbon-oxygen bond is less stiff, hence the stretching frequency is lower.

D. In first compound, C=C is not in conjugation with carbonyl C=O. Hence, it shows normal ester carbonyl freq. around 1735cm-1, whereas in second compound C=C is in conjugation with carbonyl C=O. Hence it lowers down the freq. to around 1635cm-1.

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