Alkynes

Question 1

Alkynes has the prefix _______

Answer 1

yne

Question 2

Terminal alkynes

Answer 2

Monosubstituted acetylenes

Question 3

Internal Alkynes

Answer 3

Dissubstituted acetlyenes

Question 4

What are the bases used to protonate an acetylene or terminal alkynes?

Answer 4

1. CH₉^-
2. H₂N
3. H^-
4. Acetylide ion

Question 5

When preparing alkynes they can be formed from dihalides via ___________

Answer 5

Strong base

Question 6

Alkyl dihalides can be turn into alkynes via _______ twice

Answer 6

E2 reactioon

Question 7

Geminal dihalide

Answer 7

Both halogens are connected to the same carbon

Question 8

Vicinal dihalides

Answer 8

Two halogens are connected to adjacent carbons

Question 9

_________ & __________ are the bases used for turning alkyl dihalides into alkynes

Answer 9

NaNH₂, NH₃

Question 10

A terminal alkyne can be prepared with ___________ soidum amide

Answer 10

Excess (xx)

Question 11

Sodium amide

Answer 11

NaNH₂

Question 12

Alkynes can undergo catalytic hydrogenation & also can use a poisoned catalyst to covert alkyne into a _______ alkyne

Answer 12

Cis Alkyne

Question 13

What are the types of poisoned catalyst that can be used to form a cis alkene?

Answer 13

Lindlar’s Catalyst

Question 14

What is the sterochemistry of catalylic hydrogenation involving alkynes?

Answer 14

Syn Addition

Question 15

______________ reduction can turn alkynes into trans alkenes

Answer 15

Dissolving metal reduction

Question 16

What is the reagents used in a dissolving metal reduction?

Answer 16

Na in NH₃

Question 17

What is the mechanism for dissolving metal reduction?

Answer 17

1. Nucleophilic attack
2. Proton transfer
3. Nucleophilic attack
4. Proton transfer

Question 18

A ____________ arrow shows the movement of one electron

Answer 18

Half arrow (Fish hook arrow)

Question 19

To produce an alkane an alkyne can be treated with _____ & a metal catalyst like Pt,Pd, or Ni

Answer 19

H₂

Question 20

To produce a Cis alkene an alkyne can be treated with H₂ & a _________ catalyst

Answer 20

Poisoned Catalyst (like Lindlar’s Catalyst or Ni₂B)

Question 21

To produce a trans alkene an alkyne can be treated with ______ in _______

Answer 21

Na in NH₃

Question 22

Alkynes can undergo hydroboration oxidation, what is the regiochemistry & stereochemistry?

Answer 22

1. Regiochemistry is anti-markonvikov addition
2. Stereochemistry is syn addition

Question 23

What is the mechanism for hydrohaolgenation with alkynes?

Answer 23

1. Proton transfer
2. Nucleophilic attack

Question 24

When terminal alkyne is treated with ____________ during hydrohalogenation an anti-Markovnikov addition is obsverved where the Br is positioned at the terminal position which produces E & Z isomers

Answer 24

HBr, ROOR (Radical addition can only happen with HBr (Not HCl or HI))

Question 25

Alkyne can undergo acid catalyzed hydration but _________ is used to catalyzed the reaction

Answer 25

HgSO₄

Question 26

What is the mechanism for Acid - catalyzed hydration tautomerization ?

Answer 26

1. Proton Transfer 2. Proton Transfer An resonance - stablized intermediate forms to then form a ketone

Question 27

Tautomers

Answer 27

Constitutional isomers that are rapidly intercovertted via the migration of a proton

Question 28

Ketoenol tautomerization

Answer 28

Intercoversion between an enol & ketone

Question 29

Alkynes can also undergo hydroboration - oxidation by using ____________ reagents

Answer 29

The same reagents

Question 30

What is the mechanism for Base catalyzed tautomerization (hydroboration - oxidation)?

Answer 30

1. Proton transfer 2. Proton transfer An enolate ion is formed to then form an aldehyde

Question 31

\_\_\_\_\_\_\_\_\_\_ are used to prevent the 2nd addition of BH₃ in an hydroboration - oxidation reaction

Answer 31

Dialky boranes (R₂BH)

Question 32

What are the two most common dialkyl boranes?

Answer 32

1. Disamyl borane 2. 9-BBN

Question 33

Having dialkyl boranes as the reagent can turn a terminal alkyne into an \_\_\_\_\_\_\_\_\_\_\_

Answer 33

Aldehyde

Question 34

Acid - catalyzed hydration of a terminal alkyne produces a ___________ as a product & hydroboration - oxidation produces __________ as the product

Answer 34

Methyl Ketone, An Aldehyde

Question 35

Alkynes can udergo halogenation but since it has 2 double bonds (π bonds) it can have \_\_\_\_\_\_\_\_\_\_\_

Answer 35

4 Halogens (tetrahalide)

Question 36

Can add only 2 halogens to produce a dihalide via _________ where the E isomer is the major product

Answer 36

Anti-addition

Question 37

Alkynes can undergo ozonolysis reaction where when treated with O₃ & Water it can form __________ as it products

Answer 37

Carboxylic Acids

Question 38

When a terminal alkyne undergo oxidative cleavage the terminal side is converted into \_\_\_\_\_\_\_\_\_\_

Answer 38

Carbon dioxide ( & carboxylic acid) as products

Question 39

Alkylation

Answer 39

Installs an alkyl group onto a terminal alkyne

Question 40

What are the reagents used in alkylation of terminal alkynes ?

Answer 40

1. NaNH₂ 2. RX (only methyl or primary alkyl halides)

Question 41

Alkenes can be converted into alkynes via ___________ followed by elimination

Answer 41

Bromination