ORGANIC CHEM TEST 3 THIS LATEEST

Substrate

Where the reaction takes place, characterized by polar bond

Nucleophile

- Going to be the one that donates electron pairs or donates electron density

- Must have at least one lone pair of electrons to donate

- Is attracted to carbons that is positive

Leaving group

Group that's to be substituted for by nucleophile

- can leave as anion or neutral species

- The weaker the base = the better leaving group

- good leaving groups are stable

Transition state

High energy state of the reaction

Activation energy

Energy difference between the reactants and transition state

Free energy

energy requirement for reactance to move towards transition state

Hyperconjugation

Carbon cations being stabilized by electron donation via sigma bond from other carbon structures

Hammond-Leffler postulate

- Transition state for an exergonic looks very much like starting material

- Transition state for endergonic looks like product

Polar Protic Solvents

- Hydrogen atom attached to strongly electronegative atoms

- Solvate nucleophiles and make them less reactive

- Slow down SN2 reaction by stabilizing nucleophile

polar aprotic solvents

- Do not have hydrogen attached to an electronegative atom

- Eelecent for SN2 reactions

Cahn-Ingold convention

Used to assign the groups of highest priotity on each carbon (E)-(Z)

Zaitsev's rule

when 2 different alkene products are possible in an elimination, only true if small base like ethoxide is used

Hoffman product

major product is the least substance alkene with bulky base

When the leaving group leaves from a stereogenic center of an optically active compound in an SN1 reaction, racemization will occur

This is because an achiral carbocation intermediate is formed

SN2

- Substrate: 1 or methyl

- Nucleophile = strong (-)

Ex: OH-, Br-, I-, CH3O-

- Solvent Polar aprotic: DMSO and acetone

- Mechanism: 1 step: nucleophile attacks and leaving group leave

- Kinetics: depends on substrate and nucleophile

- Stereochemistry inversion of configuration if it is chiral

- Likes methyl, 1, 2, 3

- Polar aprotic solvent

SN1

- Substrate: 3 or 2 (sometimes

- Weak nucleophile

- Mechanisms: 2 step, LG leaves, carbocation forms (carbocation is sp2), then nucleophile attacks, has intermediate formed = carbocation

- Kinetics: depends on substrate

- Likes 3, 2, 1, methyl

- Polar protic (solvent that has OH, or NH)

- Sterochemistry: racemic mixture

E1

- Substrate: 3, or 2 *sometimes

- Base: strong acids: H2SO4, H3PO4

- Polar protic

- Product: alkene (Zaitsev favored)

- Kinetics: substrate

E2

Substrate: 2 or 3, (1(only with bulky base)

- Needs strong small base: NaOEt, NaOMe (Zaitsev), or bulky base t-Buok (Hoffman)

- Mechanism: 1 step, base removes B-H, double bond forms, LG leaves

- Must be anti-coplanar

- Kinetics - substrate and base

Exothermic

Releases energy, products lower than reactants (Usually SN2)

Endothermic

Releases energy, products are higher energy (USually SN1)

Beta hydrogen definition

hydrogen on adjacent carbon

Alkene stability order

tetra > tri > di > mono