Question

In my organic chemistry class we just did the resolution of (S)-(+) Ibuprofen enantiomer, and in my lab report it asks us to discuss why the recemate has a different melting range from a pure enantiomer of the same substance, but i'm not realy sure why? DOES someone understand this and can explain this to me, i keep finding different answrers on the internet and one says that its because of affinity? what does that mean?

Answer 1

One single enantiomer (either R or S isomer) is always a puriest form of the compound w.r.t. 3D structure of individual molecule in a solid.

• If racemic mixture is there than its a mixture of compound in which R and S enantiomer are in equal amount.
• The interaction or intermolecular forces in 3D space of one isomer R or S will interact differently with other S or R isomer. So, in the soild of R + S mixture (racemate) will have different and range of mp ()lattice energy than pure R or S isomer single.
• Moreover mixture of R and S behaive like impuirity of one isomer with other.

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