5. Electrophilic Addition Reactions to Alkenes and Alkynes

Question 1

describe a general hydrohalogenation reaction.

Answer 1

there is a molecule with a double bond. A halogen is added to the carbon of the double bond that is more substituted and hydrogen is added to the opposite part

Question 2

what are typical acids used in acid-catalyzed reactions?

Answer 2

strong acids like sulphuric acid, H2SO4, and hydrochloric acid, HCl

Question 2

describe a general acid-catalyzed hydration reaction

Answer 2

there is a molecule with a double bond. A hydroxyl is added to the carbon of the double bond that is more substituted and hydrogen is added to the opposite part

Question 3

describe a general hydroboration reaction

Answer 3

there is a molecule with a double bond. A hydroxyl is added to the carbon of the double bond that is less substituted and hydrogen is added syn meaning on the same side of the double bond

Question 4

describe a general halogenation reaction.

Answer 4

there is a molecule with a double bond. Two halogens are added in a trans fashion on the double bond

Question 5

what does cis mean in halogenation reactions?

Answer 5

only either wedge or dash

Question 6

what does a double bond do to two halogens in a halogenation reaction?

Answer 6

consumes both the halogens

Question 6

what does trans mean in halogenation reactions?

Answer 6

both wedge and dash

Question 7

is an aromatic molecule reactive or unreactive?

Answer 7

unreactive

Question 8

what do the bonds in the product look like for a benzene in a halogenation reaction?

Answer 8

wedge or dash bonds

Question 9

what are the steps to solve a general ozonolysis reaction?

Answer 9

1. cut the molecule in half from where the double bond is
2. add oxygens to the ends of the double bonds

Question 10

describe a dihydroxylation reaction.

Answer 10

there is a molecule with a double bond. two hydroxyl groups are added to either side of the double bond cancelling out the double bond

Question 10

describe a general epoxidation reaction.

Answer 10

a double bond turns into a triangle with an oxygen

Question 11

what is used in an epoxidation reaction?

Answer 11

RCO3H

Question 12

what are the three types of hydrogenation reactions?

Answer 12

1. reduction of alkynes and alkenes to make alkanes with H2 and Pd/C
2. reduction of alkynes to make cis alkenes with H2 and Lindlar
3. reduction of alkynes to make trans alkenes with metal or liquid ammonia

Question 13

describe a general hydrohalogenation reaction in terms of hydrogens.

Answer 13

a double or triple bond is reduce with added hydrogens

Question 14

what are the two partial hydrogenation reactions

Answer 14

-pausing at alkenes

1. reduction of alkynes to make cis alkenes with H2 and Lindlar
2. reduction of alkynes to make trans alkenes with metal or liquid ammonia

Question 15

Describe the general reaction when there is reduction of alkynes to make cis alkenes with H2 and Lindlar?

Answer 15

A triple bond is turned into a double bond and two hydrogens are put on the same side of the double bond

Question 16

Describe the general reaction when there is the reduction of alkynes to make trans alkenes with metal or liquid ammonia?

Answer 16

A triple bond is turned into a double bond as two hydrogen atoms are put in a trans fashion on a double bond

Question 17

What are tertiary carbocations?

Answer 17

When one carbon has three other carbons surrounding it

Question 18

What is a secondary carbon?

Answer 18

When one carbon is surrounded by two other carbons

Question 19

What is a primary carbon?

Answer 19

When one carbon is surrounded by one other carbon

Question 20

What is a benzylic carbon?

Answer 20

A carbon with a benzene ring

Question 21

What is an allylic carbon?

Answer 21

carbon is bonded to a carbon atom which is double bonded to another carbon

Question 22

Which type of carbocations is more stable

Answer 22

A carbocation that is more substituted

Question 23

Why do carbocations rearrange?

Answer 23

To produce a more stable form

Question 24

What is a 1, 2-hydride shift?

Answer 24

When a positive charge on a carbon switches spots with a hydrogen for the sake of stability

Question 25

What is a 1,2-methyl shift?

Answer 25

With a positive charge on a carbon switches spots with a methyl group for the sake of stability

Question 26

What is a terpene?

Answer 26

A five carbon isopropene

Question 27

What are terpenes made from?

Answer 27

Dimethylallyl pyrophosphate, DMAPP or it’s constitutional isomer isopentenyl pyrophosphate, IPP

Question 28

What is a key intermediate in terpene synthesis?

Answer 28

Geranyl Pyrophosphate, GPP

Question 29

Describe a general terpene reaction?

Answer 29

There is a double bonded molecule with an OPP attached. The carbon with the OPP gives its electrons from its bond to OPP and gets a positive charge

Question 30

What molecules are used above and below the arrow in an acid catalyze reaction?

Answer 30

H+ or H3O above the reaction arrow and water below the arrow

Question 31

What molecule is used in a hydrohalogenation reaction?

Answer 31

A hydrogen attached to an halogen

Question 32

What molecules are used in hydro boration?

Answer 32

BH3 and THF above the reaction arrow and H2O2 and NaOH below the arrow

Question 33

What molecules are used above and below the arrow in halogenation reactions?

Answer 33

Two halogens above the reaction arrow and CCl4 below the arrow

Question 34

What molecules are used in ozonolysis?

Answer 34

O3 above the reaction arrow and (CH3)2S below the arrow

Question 35

What molecules are used above and below the arrow in dihydroxylation?

Answer 35

OsO4 above the reaction arrow and NaHCO3 or OH below the arrow