Please help! Thanks in advance! Consider the NMR spectrum of a pure sample of th
ID: 899607 • Letter: P
Question
Please help! Thanks in advance!
Consider the NMR spectrum of a pure sample of the Diels-Alder product. Match the signal pairs with the proton pairs listed on the numbered structure. Base your answer on chemical shifts for the signals expected from theory (consult the lecture textbook, Chapter IB). Signal pairs signals at delta 5.9 and 5.6 signals at delta 4.5 and 4.2 signals at delta 2.8 and 1.2 Protons pairs H1 alpha and H1 beta Protons for CH_3 and H5 Protons H6 and H7 What is the expected splitting pattern for the CH_3 protons? Choose one of the following: singlet, doublet, triplet, quartet, or doublet of doublets Can you tell from the impure spectrum what the impurity is? Make your best prediction. An ex0 transition state in the Diels-Alder reaction would have given the following initial Diels-Alder product: Would this first stage product form a lactone in the second stage? If yes, draw the structure. If no, explain.Explanation / Answer
1) matching
I ----------> C
II ----------->A
III-------------> B
2)
CH3 will be split up into doublet . because one neighbouring proton is there (H5)
3)
there may be water is impurtiy . this compound contain -COOH functional group . it can form hydroen bond with water . so water may be impurity . in the impurity specturm -COOH proton is not available for NMR resonance.
4)
no . lactone cannot form from the product . because the the -OH group is in one plane and C=O group is in another plance . so there is no possibilty to form lactone