4/18/2024

Question 1

if the energy of the products is less than the reactants what is the ∆G

Answer 1

it is negative and a spontaneous reaction

Question 2

what is the pka for a terminal alkyne and what does it mean

Answer 2

the pka is 25, meaning it is acidic enough to undergo deprotonation

Question 3

what is alkylation

Answer 3

the process of creating a new carbon carbon bond

Question 4

what is alkylation best performed with?

Answer 4

acetylide ion (carbanion intermediate) and a primary or methyl alkyl halide.

Question 5

what happens if you try to perform alkylation with a secondary or tertiary alkyl halide?

Answer 5

the mechanism will occur through an E2 pathway which will lead to an unproductive formation of an alkene

Question 6

what is an acetylide

Answer 6

it is the carbanion intermediate that forms when a terminal alkyne is deprotonated

it can act as a nucleophile and is electron rich

Question 7

why is the production of an alkene through the use of a acetylide ion and a secondary/tertiary alkyl halide unproductive?

Answer 7

it’s unproductive because if we wanted an alkene we should have used a less expensive base rather than an acetylide ion

Question 8

why shouldn’t you use an acetylide ion with a secondary or tertiary alkyl halide if the goal is to make an alkylation?

Answer 8

if you use a secondary or tertiary, the acetylide ion would rather act as a base (steric effect) and preform an E2 reaction which would result in an alkene rather than an alkylation

Question 9

what is hydrogenation

Answer 9

it is the reduction of an alkene to an alkane through the addition of two hydrogen atoms across a double bond.

Question 10

what are catalysts used for in a hydrogenation process?

Answer 10

they help speed up the reaction by lowering the activation energy and help deliver the hydrogens to either side of the double bond on the alkene

Question 11

if we subject an alkyne to hydrogenation, what will happen? will it stop at the alkene?

Answer 11

no, the reaction will proceed all the way until it becomes an alkene

Question 12

how can we stop an alkyne from continuing the hydrogenation past the alkene?

Answer 12

we can use a poison catalyst to slow it down

Question 13

if we react an alkyne with Lindars catalyst, what will form?

Answer 13

a cis alkene

Question 14

why do we only get the cis alkene when using lindars catalyst

Answer 14

lindars catalyst prevents rotation of the molecule, this forces the H2 to be added to the same side of the molecule, resulting in a cis alkene

Question 15

What do we use when we want to stop a hydrogenation reaction with an alkyne?

Answer 15

you can use lindars catalyst to form a cis alkene

Question 16

what is a dissolving metal reduction

Answer 16

it is the use of 2 lithium or sodium metal in ammonia or ethylamine at low temperatures to produce a trans alkene.

Question 17

what is retrosynthetic analysis

Answer 17

working backward from the target molecule to the synthesis required

Question 18

if you have an asymmetric alkene, where was the carbocation form

Answer 18

more subst

Question 19

if you have an asymmetric alkene, where does the carbocation form

Answer 19

the tertiary

Question 20

what is markovnikovs rule

Answer 20

it is when the hydrogen atom adds to the carbon atom of the double bond that has the most number of hydrogens

Question 21

what does a dissolving metal reduction result in

Answer 21

trans alkene

Question 22

what does a reaction with lindars catalyst result in

Answer 22

cis alkene

Question 23

what is an electrophillic addition

Answer 23

you take an alkene and react it with a halogen, this results in an alkyl halide

Question 24

what is a hydration

Answer 24

it is where we treat an alkene with h20 and an aqueous acid to form an alcohol

Question 25

in an electrophillic addition, what is the nucleophile?

Answer 25

the electron density in the double bond serves as the nucleophile while the polar bond between a halogen and a hydrogen serves as the electrophile

Question 26

why does the H-X act as an electrophile in an electrophilic addition?

Answer 26

the H-X is a polar covalent where the H is a electrophilic center

Question 27

what is a stereo selective reaction

Answer 27

A stereoselective reaction is a reaction that prefers a specific stereoisomer over another.

Question 28

what is a regioselective reaction

Answer 28

Any process that favors bond formation at a particular atom over other possible atoms

Question 29

what is a syn addition

Answer 29

it is when we place parts of the adding reagent on the same side of the reactant

Question 30

when we add H2 on a lindars catalyst to a alkyne, what is the product

Answer 30

this results in a syn addition and the formation of a cis (typically Z) alkene

Question 31

what is an anti addition

Answer 31

it is when the parts of the added reagent are added on opposite sides of the reactant

Question 32

what is an anti addition of hydrogen to an alkyne

Answer 32

it is when a trans or E alkene is formed as a result of a dissolving metal reduction

Question 33

When deprotonating a terminal alkyne with NaNH2, what is formed that drives the reaction forward?

Answer 33

the formation of NH3 which is very stable

Question 34

what is the purpose of the lithium in a dissolving metal reduction

Answer 34

it acts as a source of electrons

Question 35

what is the purpose of the ethylammine in a dissolving metal reduction

Answer 35

it acts as a source of protons

Question 36

what are the three ways to reduce an alkyne

Answer 36

you can use an H2/Pt or Pd Catalyst to preform hydrogenation and form an alkane

you can use Lindar’s Catalyst to form a cis alkene

you can use 2Li, 2 ethylammine in ammonia chloride to form a trans alkene

Question 37

if you reduce an alkyne with lindars catalyst, what is the product

Answer 37

a cis alkene

Question 38

if you reduce an alkyne with 2 Li, 2 ethylammine in ammonia chloride, what do you get

Answer 38

a trans alkene

Question 39

if you subject an alkyne to an H2/Pt catalyst, what will the product be

Answer 39

an alkane