Organic Chemistry and Biochemistry
The Organic Chemistry and Biochemistry domain tests carbon bonding, functional groups, nomenclature, isomerism, reaction patterns, and the structure and function of biomolecules. Expect items on alkanes, alkenes, alkynes, alcohols, carbonyl compounds, carboxylic acids, polymers, carbohydrates, lipids, proteins, and nucleic acids.
Core rules and concepts
- Carbon forms four bonds and catenates, producing chains, branches, and rings.
- Functional groups determine reactivity and properties: hydroxyl, carbonyl, carboxyl, amino, ester, amide, and phosphate groups are common.
- Isomers share a molecular formula but differ in connectivity or spatial arrangement.
- Addition reactions occur at double or triple bonds; Markovnikov’s rule places H on the carbon with more hydrogens in HX addition to an alkene.
- Substitution and elimination compete for saturated carbon centers; oxidation increases C–O bonds or decreases C–H bonds.
- Proteins have primary through quaternary structure; enzymes are biological catalysts that lower activation energy.
Worked example
Predict the major product of HBr addition to propene, CH₃CH=CH₂. The double bond attacks HBr. Markovnikov’s rule gives H to the terminal carbon with more hydrogens, producing a secondary carbocation at the middle carbon. Bromide then attacks that carbocation, yielding 2-bromopropane, CH₃CHBrCH₃, as the major product. The minor product, 1-bromopropane, would come from the less stable primary carbocation.
Traps that cost marks
- Applying Markovnikov’s rule backward.
- Treating resonance structures as isomers.
- Ignoring functional-group priority in nomenclature.
- Confusing primary, secondary, and tertiary protein structure.
- Assuming all biological polymers are proteins.