Orgo I: Chapter 7: Alkenes: Structure and Reactivity

unsaturated

Fat with less than the maximum number of hydrogens

degree of unsaturation formula

(2+2C + N - X - H)/2

Step One in Naming Alkenes

Name the parent hydrocarbon (longest carbon chain with a double bond)

Step Two in Naming Alkenes

Number the carbon atoms in the chain (beginning at the end nearest to the double both or if both are equidistant, nearest the first branch point)

Step Three of Naming Alkenes

Write the full name (list substituents alphabetically, number the position of the double bond(s))

For cycloalkenes where does numbering start

around the double bond

ethylene

ethene

Propylene

propene

isobutylene

2-methylpropene

isoprene

2-methyl-1,3-butadiene

what is the phrase for remembering the Z geometry

ze zame zide

are cis alkenes more or less stable than trans and why?

less stable due to steric strain

are monosubstituted alkenes more or less stable?

less stable tetrasubstituted is most stable

hyperconjugation

Stabilizing interaction between a p orbital and properly oriented C-H sigma bonds on neighboring carbons that are roughly parallel to the p orbital

which is stronger sp3-sp3 bond or sp3-sp2 bond and what is the impact on stability?

sp2-sp3 is somewhat stronger so a higher ratio of sp3-sp2 bonds are more stable

do alkenes behave as nucleophiles or electrophiles in polar reactions

nucleophiles donating an electron pair from the double bond

electrophilic addition reaction

hydrogen atom on electrophile H-X attacked by electrons from nucleophilic double bond forming a new C-H bond leaving the other carbon C+ and leaving X-, the X- donates an electron pair to the C+ yielding a neutral addition product

which molecules can successfully complete electrophilic addition to alkenes and with what catalyst

HCl reactant, ether solvent, (HI) KI reactant, H3PO4 solvent, H20 reactant, H2SO4 solvent

regiospecific

only one of two possible directions of addition occurs

Markovnikov's Rule

H attaches to carbon with fewer alkyl substituents and X attaches to carbon with more alkyl substituents, also the more highly substituted carbocation is formed as the intermediate

Hammond Postulate

the transition state is more similar in structure to the species to which it is more similar in energy

hydride shift

the shift of a hydrogen atom and its electron pair between neighboring carbons