Unit 16: Alkene Electrophilic Additions

Question 1

Nucleophiles are _________ and act as _______ in chemical reactions.

Answer 1

electron-rich
Lewis Bases

Question 2

Electrophiles are ________ and get attacked by _______ in chemical reactions.

Answer 2

electron-poor
nucleophiles

Question 3

Syn-addition: new atoms are on ________ of the double bond (_______)

Answer 3

the same side
both dashed or both wedged

Question 4

Anti-addition: new atoms are on _________ of the double bond (_______)

Answer 4

opposite sides
1 dash and 1 wedge

Question 5

Electrophilic Addition: the addition of _______ to a ________ in an alkene

Answer 5

electrophilic species
pi-bond

Question 6

Nucleophile: “excess” of…

Answer 6

negative charges, has a lot of e-

Question 7

Electrophile: “excess” of…

Answer 7

positive charges, are missing e-

Question 8

Nucleophiles are Lewis ______, since they _______ electrons

Answer 8

bases
donate

Question 9

Electrophiles are Lewis ______, since they _______ electrons

Answer 9

acids
accept

Question 10

Markovnikov’s Rule: In the addition of H-X to an alkene, H is added to the LESS SUBSTITUTED carbon which is the carbon…

Answer 10

with the greatest number of hydrogens bound to it or fewest number of non-hydrogen atoms

Question 11

Regioselectivity: When in a reaction, one __________ is preferred to all other possible ___________

Answer 11

direction of bond breaking/forming
directions of bond breaking/forming

Question 12

Stereoselectivity: When ________ is formed in preference to all others

Answer 12

one stereoisomer

Question 13

Hydrohalogenation
Regioselectivity:
Stereoselectivity:

Answer 13

Hydrogen halides (HCl, HBr, HI, etc..) “add” to alkenes
Markovnikov
N/A - only one stereocenter is generated

Question 14

Acid-Catalyzed Hydration (Addition of _______ to an Alkene)
Regioselectivity:
Stereoselectivity:

Answer 14

water
Water will add to alkenes in the presence of acid (most often: sulfuric acid)
Markovnikov
N/A - only one stereocenter is generated

Question 15

Halogenation
Regioselectivity:
Stereoselectivity:

Answer 15

Br and Cl are the most common halogens added to alkenes
Regioselectivity: N/A b/c adding two of the same substituent to the double bond
Stereoselectivity: anti

Question 16

Halohydrin formation (Addition of __ and __)
Regioselectivity:
Stereoselectivity:

Answer 16

OH, X
Reacting a halogen (Br2 or Cl2) with an alkene in the presence of water generates a halohydrin
Markovnikov (halogen added to less substituted carbon)
Stereoselectivity: Anti