Organic Chemistry 1 Final Review

Formula for formal charge?

valence electrons – (lone pair electrons + ½ bonding electrons)

What do low pKa values indicate?

Stronger acids

What is resonance?

Delocalization of electrons across multiple structures that differ only in electron placement

In an acid-base equilibrium, which side is favored?

weaker acid

What is the most stable Newman conformation?

Anti-staggered

What is torsional strain?

Electron repulsion caused by eclipsing

What is steric strain?

Repulsion when bulky groups are too close to each other

What are constitutional isomers?

Compounds with the same formula but different connectivities

What are geometric (cis/trans) isomers?

Molecules with the same connectivity but different spatial arrangement

What is angle strain?

Energy increase when bond angles deviate from ideal values

Axial position

straight up/down

Equatorial position

outward around the ring

Why are equatorial substituents more stable?

avoid 1,3-diaxial interactions

What is a chiral center?

A tetrahedral carbon with four different groups attached

What is an enantiomer?

non-superimposable mirror image

What is a diastereomer?

Stereoisomers that are not mirror images

What is a meso compound?

molecule with stereocenters that is achiral due to an internal plane of symmetry

What does ΔG tell you about a reaction?

Whether products or reactants are favored

What does ΔG‡ (activation energy) determine?

Reaction rate

What is a transition state?

Highest-energy point in a reaction step

What makes alkenes more stable?

Higher substitution, trans > cis, conjugation

What is Markovnikov’s Rule?

electrophile adds to the most substituted carbon

Mechanistic reason for Markovnikov addition?

Forms the more stable carbocation intermediate

Which alkene reactions form racemic mixtures?

Any reaction with a flat carbocation intermediate

What is the Hammond Postulate?

Transition states resemble the species (reactant/product) they're closest in energy

What causes carbocation rearrangements?

Formation of a more stable carbocation

What is the regiochemistry of HX addition to an alkene?

Markovnikov

Stereochemistry of Br₂ addition to alkenes?

Anti addition

What are the reagents for halohydrin formation?

X₂ + H₂O

Hydroboration–oxidation: reagents

1) BH₃·THF 2) H₂O₂, HO⁻

Hydroboration–oxidation: regioselectivity, stereochemistry?

Anti-Markovnikov, syn addition

Hydrogenation (H₂/Pd): stereochemical outcome?

Syn addition of H₂

Syn dihydroxylation reagents?

OsO₄ or KMnO₄ (cold, dilute) → syn OH/OH

Ozonolysis: what does it do?

Cleaves C=C to carbonyl compounds

HX addition to alkynes: regiochemistry?

Markovnikov

Hydration of terminal alkynes with HgSO₄/H₂SO₄ gives…?

Enol → keto tautomer

Hydroboration–oxidation of terminal alkynes gives…?

Enol → aldehyde (anti-Markovnikov hydration)

Lindlar’s catalyst gives what product from an alkyne?

Cis (Z) alkene, syn addition of H₂

Na/NH₃ (l) reduction of alkynes gives what?

Trans (E) alkene, anti addition

Why are terminal alkynes acidic?

The sp-hybridized carbon has 50% s-character, stabilizing the conjugate base

What is allylic/benzylic bromination reagent?

NBS + light/heat

What are the three radical mechanism phases?

Initiation, Propagation, Termination

Relative stability of carbon radicals?

Allylic/benzylic > 3° > 2° > 1° > methyl

How do you make a Grignard reagent?

RMgX from R–X + Mg in dry ether

What is a Gilman reagent?

R₂CuLi — used for substitution on organohalides and selective couplings

Suzuki coupling: key ingredients?

Aryl/vinyl halide + boronic acid + Pd catalyst + base