[orgoclear]

Refer to the attached fig.

Would the absolute configuration (R-S) of the compound be
2R,3S or 2S,3R or can it be both?

[sjb]

No figure as far as I can see. You can upload pictures directly, mind.

[orgoclear]

oops.. I thought i had uploaded it

[sjb]

As it's a meso compound, both names actually refer to the same moiety.

[orgoclear]

thanks i was wondering about that.

in the book, the options were given as
(a) 2-R,3-S and (b) 2-S,3-R

and in the answers provided, it gave only one of them as correct.

[fawad0418]

its 2S, 3R

[Smrt guy]

The 2 and 3 C atoms are equivalent so the numbering is arbitrary. 

[sjb]

Actually, the more I think about it, there is a preferred naming for meso compounds, whereby (R) has priority over (S), or something like that, so there may only be one answer.

I'm not sure of the exact rule though.

S