Alkene Structure and Reactions

Flashcards covering Alkene Structure, Nomenclature, and Reactions

Alkene Nomenclature

Naming alkenes including mono-, di-, tri-, tetra-substituted and E, Z isomers

Alkene

A hydrocarbon containing at least one carbon-carbon double bond.

Alkene Nomenclature (linear) Step 1

Select the longest chain, with the most substituents, that contains C=C as the parent name and change the suffix of the alkane with identical length from –ane to –ene

Alkene Nomenclature (linear) Step 2

Number the chain to include both carbon atoms of C=C, ensuring C=C has the lowest locants, and the location of is determined by the first atom of C=C.

Alkene Nomenclature (linear) Steps 3 & 4

Indicate the locations of the substituent groups by the numbers of the carbon atoms to which they are attached and Label (E) or (Z) before full name if necessary

Alkene Nomenclature (cyclic)

Number substituted cycloalkenes to give the atoms of C=C the 1 and 2 positions and give the substituent groups the lower numbers at the first point of difference

Synthetic Organic Chemists

Use tools to create novel or target compounds for drug discovery, petrochemicals, food, materials, etc.

Catalytic Hydrogenation

Addition of H2 across C=C pi bond, Stereospecific (syn), no carbocation generation (no rearrangement), no regioselectivity, and stereochemistry (racemization)

Hydrogenation Energy of Alkenes

The most stable alkene isomer releases the smallest amount of heat upon hydrogenation.

Hydrohalogenation

Addition of H-X across C=C pi bond (X = Br, Cl), carbocation generation (possible rearrangement), not stereospecific, regioselective (Markovnikov addition), and stereochemistry (racemization)

Markovnikov’s Rule

Hydrogen atom adds to the carbon atom of the double bond that has more hydrogen atoms. Heteroatom adds to the carbon atom of the double bond with the more carbon atoms. Carbocation resides on the carbon atom where it would be most stable

Halogenation - Mechanism

First step (NA + LOLG): Br2 is the electrophile, pi bond is nucleophile, Br- is lost as a LG, and a bridged intermediate Bromonium ion is formed, Second step (nucleophilic attack): Br- (LG) is nucleophile, carbon with bromonium ion is electrophile.

Halo-hydrin Formation - Mechanism

First step (NA + LOLG): Br2 is the electrophile, pi bond is nucleophile, Br- is lost as a LG, and a bridged intermediate Bromonium ion is formed, Second step (NA): H2O is nucleophile, carbon with bromonium ion is electrophile, NA at the most substituted carbon. Third step (PT): solvent (H2O) is the base, to deactivate the alcohol.

Acid-Catalyzed Hydration

Acid-catalyzed Hydration, Addition of H–OH a C=C pi bond, carbocation generation (possible rearrangement), regioselective (Markovnikov’s rule), no stereospecificity and stereochemistry (racemization)

Hydrohalogenation- Mechanism

First step (PT): H+ is the electrophile, pi bond is nucleophile, carbocation generation (possible rearrangement), second step (nucleophilic attack): X- is the nucleophile, carbocation is electrophile. Carbocations are achiral and trigonal planar • Not stereospecific • Regioselective (Markovnikov addition) • Stereochemistry (racemization)

Mechanisms

Describe the step-by-step process by which reactants are converted into products determined experimentally