| Date | May 2011 | Marks available | 1 | Reference code | 11M.3.hl.TZ1.F4 |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Comment | Question number | F4 | Adapted from | N/A |
Question
The stereochemistry of molecules affects the way they interact with taste and smell receptors in the body.
The stereochemistry of carbohydrates and amino acids is usually indicated by the D/L convention.
Alanine has the formula \({\text{[}}{{\text{H}}_{\text{2}}}{\text{N}}–{\text{CH(C}}{{\text{H}}_{\text{3}}}{\text{)}}–{\text{COOH]}}\). Deduce the structure of D-alanine and complete its structure below.
State which convention is usually employed to indicate the stereochemistry of molecules other than carbohydrates and amino acids.
Based on the structure given in part (b) (i) comment on the statement “D-alanine is a +(d) compound”.
Markscheme
the R– S– convention;
not possible to tell;
Examiners report
This was a low scoring question, particularly parts (b) (ii) and (b) (iii).
This was a low scoring question, particularly parts (b) (ii) and (b) (iii).
This was a low scoring question, particularly parts (b) (ii) and (b) (iii).
