chem hwk: 2-chloropropanoic acid and 2-hydroxypropanoic acid

[clarisse]

I am really lost with this question... could anyone please point me in the right direction?

 

2-chloropropanoic acid and 2-hydroxypropanoic acid can both show optical activity.

Identify the feature whcih both molecules possess that accounts for this property.

 

When 2-hydroxypropanoic acid is formed from 2-chloropropanoic acid, the product shows no optical avtivity. Deduce the type of nucleophilic substitution that takes place and explain your answer.

 

 

The first part is ok. I however can't figure out the following part. Working kind of backwards I would think that perhaps it is an Sn2 mechanism because the formation of the carbocation is not favoured because of the C=O bond of the carboxyl group and the H on the other side so the carbocation wouldn't be stabilized? I however can't see how the product isn't optically active. Help please?

[clarisse]

someone? help? please?

 

Ok, I think I know why the resulting substance wouldn't display optical activity: because it would be a recemic mixture... which means that the two enantiomers are being produced in approximately equal proportions. I however don't see how this helps explain the mechanism of the reaction.

[psynapse]

optical activity.. Does this refer to chiral molecules. If so you might want to try and produce a racimic mixture in the latter reaction.