I know this is late from your initial post and may not help you if you've taken the MCAT.
But for others, from my experience (AAMC and Kaplan practice exams, the real MCAT):
Substitution/Elimination SN2, SN1, E1, E2 **
Types of Isomers: Stereoisomers/Enantiomers **
Functional Groups **
Lab Techniques
Biochemistry- application of orgo in fatty acids, amino acids, etc
R and S configurations