Stuck On A Chemsitry A - Level Question?

Question

"2-Hydroxypropanoic acid was dissolved in D2O and an n.m.r spectrum of the solution was taken. Predict, with reasons, the splitting patterns observed in this spectrum"

Any ideas welcome.

Answer 1

2 -Hydroxy-propanoic acid: (CH3)-CH(OH)-C(=O)OH.
Let's call the methyl carbon X, the hydroxy Y, and the carboxylic acid carbon Z.

I guess you are taking an 1H NMR of the sample. There are 4 distinct types of H's in different environments, so you should get four peaks.
1) The 3 H's on the methyl group X will give a doublet, since they are split by the H on carbon Y.
2) The H on carbon Y will be split into a quartet by the 3H's on carbon X.
3) The hydroxy H on carbon Y will not be split.
4) The H signal from the carboxylic acid will not be split


Note: because the hydroxy H can be exchanged with water to some extent, it normally doesn't split or get split by nearby H's.

Wait actually since it's in deuterium, you may not see the OH and carboxylic acid H's at all, they should exhange for a D from the D2O and not contribute at all

Answer 2

BagaLagaLaga is correct w.r.t. D20 exchanging the Labile Hydrogens of the Hydroxy and acid Groups

Although you have not stated if you are looking for a 1H or 13C spectrum.

Answer 3

CH3CH(OH)COOH would be expected to have peaks corresponding to 4 different types of protons. The H atoms bonded to O will give singlets, but with different shifts, the CH3 protons will cause the C-H proton to become a quartet and the C-H proton will cause the CH3 protons to become a doublet.

Answer 4

prob cos the d20 (deuterium) slows down neutrons effectively and also has a low probability of absorption of neutrons

Answer 5

I`m so sorry but I dont have the foggiest.