Ch. 10

Question 1

When naming an alkene what is important to remember?

Answer 1

The longest chain must contain both atoms of the double bond

Question 2

How do you the suffix if there is more than one double bond in the molecule?

Answer 2

Change the -ane ending to -adiene (for two double bonds), -atriene (for three), and so forth

Question 3

Where is the double bond located in a cycloalkene?

Answer 3

Between C1 and C2

Question 4

What class of compounds contain both a double bond and a hydroxy group?

Answer 4

Alkenols

Question 5

Does the double bond or the OH group get priority when naming an alkenol?

Answer 5

The OH group gets the lower number when naming the longest chain

Question 6

True/False: When naming a cycloalkene molecule the numbering is done clockwise or counterclockwise such that the lower number goes to the first substituent after the double bond has been numbered

Answer 6

True

Question 7

When are the E and Z prefixes useful in naming?

Answer 7

When there are more than two alkyl groups bonded to the C=C

Question 8

What is an allyl group?

Answer 8

When a substituent is bonded to a carbon adjacent to (but not part of) the double bond

Question 9

What is a vinyl group?

Answer 9

When a substituent is bonded directly to a carbon of the double bond

Question 10

Do alkenes have low or high boiling points and melting points?

Answer 10

Low melting and boiling points due to weak van Der Waals forces

Question 11

Are alkenes soluble in water or organic solvents?

Answer 11

Organic solvents

Question 12

As double bonds increase what happens to the melting point of fatty acids?

Answer 12

It decreases

Question 13

What type of addition (syn or anti) occurs in hydroboration-oxidation reactions?

Answer 13

Syn addition

Question 14

What type of addition (syn or anti) occurs in halogenation and halohydrin reactions?

Answer 14

Anti addition

Question 15

What type of addition (syn or anti) occurs in hydrohalogenation and hydration reactions?

Answer 15

Syn and Anti addition

Question 16

What types of bases are typically used to dehydrohalogenate an alkyl halide to make an alkene?

Answer 16

Strong bases for the E2 mechanism such as:

t-butoxide, DBU, DBN

Question 17

What types of reagents are used in the acid-catalyzed dehydration of an alcohol to make an alkene?

Answer 17

H2SO4 and TsOH, occurring via an E1 mechanism with 2’ and 3’ alcohols, and via E2 with 1’ alcohols

Question 18

What reagents are often used to carry out dehydration of a 2’ alcohol via an E2 mechanism?

Answer 18

POCl3 and pyridine

Question 19

What reagent class is used to make an alkyl halide from a 1’ alcohol?

Answer 19

• -HX via an Sn2 mechanism.
• -The oxygen gets protonated to make it a good leaving group
• -The X- then does a backside attack

Question 20

What reagent class is used to make an alkyl halide from a 2’ or 3’ alcohol?

Answer 20

HX via an Sn1 mechanism

Question 21

When would you use SOCl2 + Pyridine

Answer 21

When you start with an alcohol and need to do an Sn2 reaction and end up with Chlorine as the new substituent on the alkyl halide

Question 22

When would you use PBr3

Answer 22

When you start with an alcohol and need to do an Sn2 reaction and end up with Bromine as the new substituent on the alkyl halide

Question 23

When would you use POCl3 + Pyridine as reagents?

Answer 23

When you start with an alcohol and need to do an E2 reaction and end up with an alkene

Question 24

When would you use Tosylate + Pyridine as reagents?

Answer 24

When you want the flexibility to do an Sn2 or E2 mechanism and retain the stereochemistry when making the OH a good leaving group

Question 25

Do alkenes react with electron-rich species such as bases and nucleophiles?

Answer 25

No. Alkenes react with electrophiles because the double bond is electron-rich