Organic Chemistry Reactions and Stereochemistry

Flashcards for reviewing organic chemistry lecture notes.

Reaction Mechanisms

A step-wise process using arrows to show how reactants become products.

Curved Arrows

Used to explain reactions, showing electron movement from a pi bond or lone pair towards an atom. Do not show atom movement.

Catalytic Reagents

Reagents used and regenerated within a mechanism (e.g., catalytic acid or base).

Tautomerization

The interconversion of two isomers, like enol and ketone forms, through proton transfer.

Grignard Reagent

An organometallic chemical reagent with the formula R-Mg-Br; acts as a carbon nucleophile when reacted with carbonyl.

Nucleophile

Electron-rich reactant (e.g., a metal in a carbon-metal bond or Grignard reagent).

Electrophile

Electron-poor reactant (e.g., a carbonyl).

Oxidative Addition (in Grignard formation)

The insertion of a metal (Mg) between a carbon and a halogen (Br).

Carbon Lithium Bond

Similar to Grignard reagents but using Lithium. Reacts similarly with Carbonyl compounds.

Hydride Nucleophiles

Sources of H- (e.g., Sodium Borohydride (NaBH4) and Lithium Aluminum Hydride (LiAlH4)). Opposite of acids (H+).

Sodium Borohydride (NaBH4)

A hydride source that acts as a nucleophile. Reacts with carbonyls to form alcohols, less reactive than LIALH4

Lithium Aluminum Hydride (LiAlH4)

A strong hydride source that acts as a nucleophile. Reacts with carbonyl electrophiles to produce alcohols, more reactive compared to NaBH4

Carbonyl Electrophiles

Acid Chlorides, Esters, Carboxylic Acids, Carboxylate Anions, Ketones, Aldehydes, Formaldehyde and CO2 that react with nucleophiles.

Leaving Group (Z)

The group that is replaced by a nucleophile during carbonyl substitution reactions, R, Cl or OR.

Carbonyl Addition

Reaction where a nucleophile adds to a carbonyl group.

Carbonyl Substitution

Reaction where a nucleophile replaces a leaving group on a carbonyl.

Esters and Acid Chlorides Product

reacts with nucleophiles (Grignard reagents, organolithium reagents, or hydrides) to form alcohol.

Carboxylic Acid

new carbonyl that is an ACID and donates H+ and is unreactive with gringnard and NaBHy.

Carboxylate Anion

reacts with strong nucleophiles like LiAlH4 →1° alcohol and R-Li.

Epoxides

Cyclic ethers that are reactive due to angle strain, reacting with nucleophiles like Grignard reagents.

Corey-Chaykovsky Reaction

Reaction used to make epoxides, works only with Ketones and aldehyde.

Wittig Reaction

Reaction that allows the creation of alkenes from ketones or aldehydes using a phosphonium ylide.

Sulfur Ylide

Reacts with ketone or aldehyde to form an epoxide.

MCPBA (meta-chloroperoxybenzoic acid)

Reagent that can convert an alkene to an epoxide.

Oxidation

More bonds to a Oxygen atom.

Reduction

Less bonds to a Oxygen atom.

PCC, DMP, H2CrO4

Oxidizing agents used to convert primary alcohols to aldehydes and secondary alcohols to ketones.

Acetal

Product of reacting ketones or aldehydes with alcohol nucleophiles under acid catalysis; protecting group.

Le Chatelier's Principle (in Acetal Formation)

Manipulating equilibrium by adding or removing water to favor product or reactant formation.

Oxonium Ion

Key intermediate and Second alcohol adds

Strong Nucleophiles (Irreversible Reactions)

RLi, RMgX, NaBH4, LiAlH4. Reactions are irreversible.

Weak Nucleophiles (Reversible reactions)

ROH, H2O, RNH2, R2NH. Reactions are reversible.

Imine & Enamine Synthesis

Reaction of ketones/aldehydes with amines under acid catalysis. Similar to acetal formation.

Imine

Product of reacting a primary amine with a ketone or aldehyde.

Enamine

Product of reacting a secondary amine with a ketone or aldehyde.

Reductive Amination

Conversion of ketone/aldehyde to amine using a reducing agent (e.g., NaCNBH3).

Sodium Cyanoborohydride (NaCNBH3)

Less reactive reducing agent than NaBH4; doesn't react with the starting carbonyl.

Reaction of Nitrites via LAH

Creates amine

Wolff-Kishner Reaction

Synthesis of alkanes from ketones and aldehydes under basic conditions.

Acyl Substitution Reaction

Reactions of carboxylic acids and their derivatives, via tetrahedral intermediate.

Hydrolysis Reactions

Reactions involving the breaking of a bond using water (acidic or basic).

Acid Chloride Synthesis

Conversion of a carboxylic acid to an acid chloride using SOCl2.

Fischer Esterification

Synthesis of an ester from a carboxylic acid and an alcohol under acid catalysis.

Constitutional Isomers

Different connectivity of atoms.

Stereoisomers

Same connectivity of atoms but different arrangement in space.

Enantiomers

Stereoisomers whose molecules are non-superimposable mirror images.

Diastereomers

Stereoisomers whose molecules are not mirror images of each other.

Chiral Molecule

Molecule that is not identical to its mirror image. And must have enantiomer.

Achiral Molecules

Molecule that is identical to its mirror image.

Plane of Symmetry

Imaginary plane that bisects a molecule such that the two halves are mirror images. All molecules with a plane of symmetry are achiral.

Chiral Center/Stereocenter/Stereogenic Center

Carbon bonded to 4 different groups.

R/S Nomenclature

System for naming enantiomers based on the ranking of substituents around a chiral center.

Carbocation Stability

3° > 2° > 1°. More substituted carbocations are more stable.

Regiochemistry

Think about where the groups are

Hydrogenation

Addition of H2 to form an alkane (syn addition).

Halogenation

Anti addition of X2 (e.g., Cl2 or Br2) to an alkene, Mechanism: No Carbocation formed.

Hyperconjugation

Explains c+ stability. This bond is in Same plane as empty P-orbital-it donates e-density to Stabilize.

Acid Hydration

Source of H+ and H2O reacts with alkene.

Hydrohalogenation

Alkene REACTION with HBr or HCl Synthesis of alkyl halides, form most stable carbocation, Syn and anti addition, beware of rearrangement.

Hydration

Alkene REACTION with H2SO4, H2O Synthesis of alcohols, form most stable Carbocation Sun and anti addition beware of rearrangement.

Dihydroxylation

Synthesis of diols, Syn addition.

Hydrogenation

Synthesis of almanes, Syn addition.

Hydroboration - Oxidation

Synthesis of alcohols, net Syn addition.

Halogenation

Synthesis of dihalides, antiaddition.

Hydrohalogenation

Sunthesis of halo alchols, anti addition.

Oxymercuration - Demercuration

Synthesis of alcohols, net sun addition

Hydro Halogenation Reactivity

REGIOCHEMISTRY: H-less Subsitue Sideand x= more subsitue Side STEREOCHEMISTRY: Both SyN+ANTI KEY INTERMEDIATE: Carbocation

Hydroboration Oxidation Stereo and Regiochem

STEREOCHEMISTRY: enantimers SYN H more sub than H2B REGIOCHEMISTRY: more sub less sub