Ochem Unit 2

Bronsted Acid

Proton Donor (wants electrons)

Bronsted Based

Proton acceptor (wants to share electrons)

Conjugate Acid

the compound after accepting proton (prior base)

• positive charge

Conjugate Base

the compound after donating a proton (prior acid)

• negative charge

Nucleophiles

• electron source

• has electrons

Nucleophilic Attack

making a bond

Proton Abstraction

removing hydrogen on El and adding to Nu

Protonation

adding hydrogen

Departure of leaving group

breaking a bond between molecule

reactive intermediates

high energy species formed between two successive reaction steps which lies in an energy minimum between the two transition states

Racemic Structures

molecules that have exact same chemical formula and the exact same connectivity of atoms, but they are arranged differently in 3D space

Electrophilic Addition

electrophilic species adds across a pi bond

Carbocation Stability

more CH3 added means increasing stability

Inductive Effect

delocalizing charge by polarizing electrons toward the electron-deficient carbocation (carbocation is better able to stabilize since it is more polarizable)

Markovnikov’s Rule

when determining structure: hydrogen is going to be added to the sp2 carbon of the double bond that has the greater number of hydrogen’s in an electrophilic addition reaction

Intermediate

real chemical species that forms during a multi-step reaction, exists for a short period, and then reacts further to form the final product

Regioselective Product

A reaction is regioselective when a chemical reagent can react at two or more different positions (regions) on a molecule, but it preferentially reacts at one specific site over the others.

• the regioselective product (often called the major product) is the isomer that forms predominantly at that favored position.

• pathway typically proceeds through a more stable intermediate.

Rearrangement: 1,2 Shift

type of rearrangement in which atom with its bonding electrons moves from one atom to an adjacent electron deficient atom

stereoselective reaction

stereoisomer is formed in preference to all others

anti stereoselective

The addition of atoms or groups of atoms to opposite faces of a carbon-carbon double bond

syn stereoselective

The addition of atoms or groups of atoms to the same face of a carbon-carbon double bond

halohydrin

a compound containing a halogen + hydroxyl group on adjacent carbons

• vicinal: atoms bonded to adjacent carbons

• geminal: atoms bonded to the same carbon

• anti stereoselective ALWAYS

rules for drawing favorable equilibrium diagrams

• pH < pKa = protonated

• pH > pKa = depronated

Stabilizing Effects: what makes something more acidic

• electronegativity: more electronegative → more acidic → more ability to stabilize

• polarizability: bigger → more acidic

• resonance: more resonance → more acidic

• inductive effect: electron withdrawing group → more acidic

• hybridization: more s character (sp > sp2) → more acidic

two common stabilization themes

1. holding electrons tight/keeping them close

   1. electronegativity and hybridization

2. spreading the electron density/sharing electrons

   1. polarizability, resonance, inductive effect

these are competing effects

reactive intermediate

high energy species formed between two successive reaction steps, which lies in an energy minimum between the two transition states

rate determining step (rate limiting step)

the step in a multistep reaction sequence that has the highest energy barrier

addition of halogen

going to be anti stereoselective + n/a regioselectivity

addition of haloyhrdrin

going to be anti stereoselective + n/a regioselectivity

Oxidation

the loss of electrons / the loss of hydrogens or the gain of oxygen

Glycoll

a compound with hydroxyl (OH) groups on adjacent carbons

• also called Vicinal Diol

• regioselectivity: N/A

• stereoselectivity: Syn

ozonolysis

cleavage of a double bond with ozone (O3) producing two carbonyl (C=O) groups in its place

• regioselectivity: N/A

• stereoselectivity: N/A

Hydroboration-Oxidation

method of converting an alkene into an alcohol

• occurs without rearrangement

• regioselectivity: non markavnikov

• stereoselectivity: Syn

reduction

gain of electrons / the gain of hydrogens or the loss of oxygens

• regioselectivity: N/A

• stereoselectivity: Syn

hydrogenation

reduction with H2 : create saturated hydrocarbons from unsaturated ones

• regioselectivity: N/A

• stereselctivity: Syn

Stereospecific Reaction

a reaction in which stereochemistry of rhe product depends on stereochemistry of the starting material