Chemistry 332 - Winter 1997

Professor Carl C. Wamser

A Brief Review of Nearly Everything

Resources for reviewing:

• Textbook chapter summaries
  • summaries of concepts
  • summaries of reactions
    
    
• Textbook appendix
  • nomenclature
    
    
• Study Guide chapter summaries
  • chapter outlines
  • chapter skills
    
    
• Study Guide appendices
  • summary of reaction mechanisms
  • summary of functional group preparations
  • reagents used in organic reactions
  • glossary
  • symbols and abbreviations

Basic Concepts

Bonding and Structure

• sp³ - tetrahedral - carbon with 4 single (sigma) bonds
• sp² - trigonal - carbon with 3 sigma bonds and 1 pi bond
• sp - linear - carbon with 2 single bonds and 2 pi bonds

IUPAC Nomenclature

• (substituents)-parent alkane-(functional group)
• only one primary functional group as the suffix, others are prefixes
• -en- or -yn- replaces the -an- in the parent name

Stereochemistry

• terminology: stereoisomer, stereocenter, chiral, enantiomer, racemic, diastereomer, meso compound, optical activity, conformations
• Newman diagrams, Fischer projections, cyclohexane chairs
• R & S , E & Z , cis & trans

Reaction Mechanisms

• energy diagrams: delta H, activation energy
• intermediates (energy wells), transition states (energy peaks)
• rate-determining step (slowest step of a mechanism determines its rate)
• kinetics: 1st-order (depends on one concentration), 2nd-order (depends on two concentrations)

Functional Group Families

Alkenes and Alkynes

• additions to the pi bond: H₂, Cl₂, Br₂, HCl, HBr, H₂O (H⁺), ozone, polymerizations
• Markovnikov Rule: add so as to form the more stable carbocation
• carbocation stability: (best) 3° > 2° > 1° > CH₃ (worst)

Aromatics

• substitution by strong electrophiles: alkyl or acyl (Friedel-Crafts), X (halogen), NO₂ (nitration), SO₃H (sulfonation)
• meta-directors (deactivating) - electron-withdrawing groups (with + charge)
• orto,para-directors (activating) - electron-donating groups (esp. with lone pairs)

Alkyl Halides

• S_N2 : backside displacement of X^- by a nucleophile
• S_N1 : 2-step substitution via carbocation
• E2 : concerted removal of H and X (anti)
• E1 : 2-step elimination via carbocation
• nucleophile: has a lone pair to be used in making a new bond
• Grignard reagents: RMgX (nucleophilic carbon)

Alcohols, Ethers

• acid-base properties like water (RO^- alkoxide anions, ROH₂⁺ oxonium ions), pKa ~ 15-18
• hydrogen bonding gives relatively high boiling points
• oxidations: 1° alcohol -> aldehyde -> carboxylic acid
  2° alcohol -> ketone
• dehydration to alkenes (H₂SO₄)
• phenols: aromatic alcohols, slightly stronger acids (pKa ~ 10)
• ethers: generally unreactive
• epoxides: 3-membered ring opens easily with nucleophiles
• sulfur compounds: like oxygen analogs, but more nucleophilic

Aldehydes, Ketones

• nucleophilic additions to the carbonyl group: H₂O, ROH, RNH₂, CN^-, Grignards
• synthesis of larger compounds (alcohols) by Grignard additions
• acid catalysis (generates a more reactive carbonyl group on protonation)
• acidic alpha hydrogens: enols, enolate anions
• the aldol condensation (aldehyde -> beta-hydroxyaldehyde)

Carboxyl Derivatives

• acids, acid halides, esters, anhydrides, amides, nitriles
• nucleophilic substitution at the carboxyl group
• hydrolysis reactions, esterification, other interconversions
  (replacement of a leaving group by a nucleophile)
• acid or base catalysis
• reactivity order: acid halides > anhydrides > esters > amides
• condensation polymers (polyesters and polyamides)
• the Claisen condensation (esters -> beta-ketoester)

Amines

• basicity, formation of ammonium ions
  alkyl ammonium ions pKa ~ 10 (aryl ammonium ions pKa ~ 5)
• synthesis by reduction of other N functional groups (amides, nitriles, nitro)
• reactions as nucleophiles (1°, 2°, 3° amines, 4° ammonium ions)
• conversion to amides
• diazonium ions from aryl amines (lead to nucleophilic substitution on the aromatic ring)

Spectroscopy

• NMR: detects different types of H (or C)
• IR: detects molecular vibrations
• UV: detects electronic transitions (molecular orbital energies)

Biomolecules

• carbohydrates, sugars
• proteins, amino acids
• lipids, steroids, fats
• nucleic acids