Chapter 6

Question 1

addition to alkenes

Answer 1

break the double bond and add two new single bonds

Question 2

reaction mechanism

Answer 2

how we get from starting material to product

Question 3

4 basic mechanism elements

Answer 3

1. Nucleophilic Attack (make a bond)
2. Proton abstraction (remove hydrogen)
3. Protonation (add hydrogen)
4. Departure of a leaving group (break a bond)

Question 4

reactive intermediate

Answer 4

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

Question 5

rate-determining step

Answer 5

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

Question 6

bond dissociation enthalpies

Answer 6

amount of energy required to break a bond into two radicals (in the gas phase)

Question 7

electrophilic addition

Answer 7

electrophilic species adds across a double bond

Question 8

inductive effects

Answer 8

spreading (=delocalizing) charge by polarizing e- toward the e- deficient carbocation

Question 9

hyperconjugation

Answer 9

interaction of electrons in a pi bonding orbital w/ vacant 2p orbital of adjacent positively charged carbon

Question 10

carbocations

Answer 10

often intermediates

Question 11

regioselective reaction

Answer 11

addition or substitution reaction where one out of multiple possible products is formed

Question 12

Markovnikov’s Rule

Answer 12

when hydrogen adds to the carbon of the double bond that has the greater number of hydrogen’s in an electrophilic addition reaction of alkenes

Question 13

hydration

Answer 13

the addition of water

-regioselective: Markovnikov addition

Question 14

Markovnikov regioselectivity

Answer 14

-H goes onto the carbon with more hydrogens

Question 15

rearrangement

Answer 15

change in connectivity of the atoms

Question 16

1,2 shift

Answer 16

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

Question 17

stereoselective reaction

Answer 17

a reaction in which one stereoisomer is formed in preference to all

Question 18

antistereoselectivity

Answer 18

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

Question 19

halohydrin

Answer 19

compound containing a halogen and a hydroxyl group on adjacent carbons

• vicinal atoms are bonded to adjacent carbons, whereas geminal atoms are bonded to the same carbon
  regioselective: halogen goes on less substituted carbon, hydroxyl goes on more substituted carbon
• stereoselective: halogen and hydroxyl add from opposite face of the double bond

Question 20

oxymercuration

Answer 20

a method for converting an alkene to an alcohol

• uses mercury (II) acetate (Hg(OAc)2) followed by reduction with sodium borohydride (NaBH4). Occurs w/o arrangement
• regioselective: Markovnikov addition
• stereoselective: Initially -HgOAc and -OH add from the opposite face of the double bond (anti stereoselective), but that stereoselectivity is removed when the -H is scrambled upon reduction of -HgOAc.

Question 21

reduction

Answer 21

the gain of electrons. Gain of hydrogen/loss of oxygen

Question 22

hyboration-oxidation

Answer 22

a method for converting an alkene into an alcohol. occurs without rearrangement

• regioselective: non-Markovnikv addition (-H goes onto carbon with fewer hydrogens)
• stereoselective: hydrogen and boron add from the same face of the double bond (syn stereoselective)

Question 23

oxidation

Answer 23

the loss of e-. Alternatively, the loss of hydrogen and or Bain of oxygen
-stereoselective: both hydroxyl groups add from the same face of the double bond (syn stereoselective)

Question 24

ozonolysis

Answer 24

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

Question 25

hydrogenation

Answer 25

reduction with molecular hydrogen (H2). Often used to create saturated hydrocarbons from unsaturated ones
-stereoselctive: both hydrogens add from the same face of the double bond (syn stereoselective)

Question 26

stereospecific reaction

Answer 26

a reaction in which the stereochemistry of the product depends on the stereochemistry of the starting material
A. achiral starting material in an achiral environment
B. chiral starting material in an achiral environment
C. achiral starting material in a chiral environment

Question 27

enantioselective

Answer 27

a reaction that produces one enantiomer in preference to the other