Grasby

Question 1

What do you get when you react R-X (X is a halide) with NaCN

Answer 1

Nitrile

Question 2

How can carboxylic acids be made from CO₂

Answer 2

By reacting it with an organometallic reagent which breaks one of the C=O. this is then followed by an acid work up

Question 3

What does a high pKa indicate

Answer 3

Strong acid

Question 4

What does a low pKa mean

Answer 4

Strong base

Question 5

Arrange these in terms of which is the best LG and state their pKa`s,

Amine, anhydride, acid chloride and alcohol

Answer 5

Chloride (HCl = -7)
Anhydride (RCOOH = 5)
Alcohol (ROH = 15)
Amine (RNH₂ = 35)

Question 6

If XH has a low pKa it shows that it is a…

Answer 6

good leaving group

Question 7

How can esters be made from acid chlorides and anhydrides

Answer 7

React ROH with base

Question 8

What role does the base play in ester formation from acid chlorides and anhydrides.

Answer 8

Takes a H from the alcohol group once it has attacked the carbonyl

Question 9

What do you get when you react an acid chloride with a carboxylate salt eg MeCOO^-

Answer 9

Anhydride

Question 10

What do you get if you react an acid chloride with 2 equalivalents of an amine

Answer 10

Amide

Question 11

Why are two equivalents of amines needed in the reaction with acid chlorides

Answer 11

One to form the amide and the other to mop up the acidic H

Question 12

Esters and anhydrides can also be used to form amides but why is chloride preferred

Answer 12

Bigger yield

Question 13

describe the schotten bauman conditions for the reaction of amides and why does this not produce a carboxylic acid.

Answer 13

2 equivalents of amine. NaOH and CH₂Cl_2.
This reaction takes place in the organic phase.

Question 14

What makes a good nucleophile

Answer 14

Strong bases and molecules with high pKa`s

Question 15

Order these in terms of decreasing electrophilicity
Ester, amine, chloride and anhydride

Answer 15

Chloride - anhyrdried- Ester - amine

Question 16

How does the inductive effect increase electrophilicity

Answer 16

More inductive effects increases the electrophilicity

Question 17

How does delocalisation affect electrophilicity

Answer 17

Decreases electrophilicity,however, lp in oxygen are lower in energy than lp in amides due to O being higher in electronegativity which means N donated lp

Question 18

Why do anhyrdrides have high electrophilicity

Answer 18

Delocalisation is shared over two carbonyls

Question 19

Can amides be made from carboxylic acid

Answer 19

No only from acid deratives

Question 20

How are acid chlorides made from carboxylic acid

Answer 20

By reacting CA with SOCl₂ or PCl₅

Question 21

How can electrophilicity be enhanced

Answer 21

protonate the carbonyl

Question 22

how can leaving group ability be enhanced

Answer 22

By protonating the Lg

Question 23

What conditions are needed for esterification

Answer 23

CA and an alcohol in acidic conditions

Question 24

Why is acid needed in esterification

Answer 24

To protonate the carbonyl and OH and also the reaction does not occur at a practical rate without acid catalysis.

Question 25

How to favour hydrolysis

Answer 25

XS water

Question 26

To favour Esterification

Answer 26

Use XS solvent eg ROH and remove H₂O by using a drying agent or by distillation

Question 27

how are Lactones formed (Cyclic esters)

Answer 27

undergo intramolecular esterification. functional groups more likely to interact if attached to same molecule

Question 28

Why cant esters be made under basic conditions

Answer 28

a carboxylate salt is formed

Question 29

What is transesterification

Answer 29

Conversion of one ester to another

Question 30

Does transesterication involve protonation of electrophile and leaving group

Answer 30

yes

Question 31

What do you get if you react esters with water under basic conditions.

Answer 31

Carboxylate salt and alcohol

Question 32

In saponification once the OH has be deprotonated is the reaction reversible

Answer 32

No as the carboxylate salt is not a nucleophile

Question 33

Why is an acid catalyst not needed when there is a good nucleophile

Answer 33

The nucleophile will be protonated turining it to a good one to a poor nucleophile.

Question 34

Explain the effect increasing acid has on imine formation

Answer 34

increases untill pH 5 then decreases

Question 35

How does an acid catalyst speed up the rate of imine formation

Answer 35

Converts poor lg into a good lg unitl pH 5

Question 36

What do you get if you react an amide with water under acidic conditions

Answer 36

carboxylic acid

Question 37

What do you get when an amide reacts with water under basic conditions

Answer 37

Carboxylic salt

Question 38

What is required to hydrolyse nitriles

Answer 38

Water and H₂SO₄

Question 39

What do you get when ROCL and an anhydride react with water

Answer 39

Carboxylic acid

Question 40

Why can`t esters be made from ketones

Answer 40

Because the product is more reactive and will react with the reagent.

Question 41

How are organocopper reagents made

Answer 41

CuBr is reacted with R-Li and ether at 78 degrees. which gives R₂Cu^-Li^- and LiBr

Question 42

What do you get when you react an amide with a R-Li (ether and H₃O⁺)

Answer 42

aldehyde

Question 43

What do you get when you react a nitrile with a grignard reagent followed by an acid workup

Answer 43

Ketone

Question 44

What is reduced by NaBH₄

Answer 44

Ketones and aldehydes

Question 45

What is reduced by LiALH₄ and acid workup

Answer 45

esters, anhydrides and chloride, even aldehydes and ketons

Question 46

What do you get when you react amide and LiAlH₄

Answer 46

amine

Question 47

How do you get an aldehyde from an ester

Answer 47

reduce the ester with LiAlH₄ followed by an acid work up and then react the alcohol with PCC, CH₂Cl with no water.

Question 48

Name some properties of amino acids

Answer 48

All chiral except glycine and have the same stereochemistry. At pH 7 as zwitterions

Question 49

what do you get if you react an acid chloride and carboxylate salt

Answer 49

anhydride

Question 50

What do you get if you react an ester with an amine and comment on the rate of reaction

Answer 50

Amide and reaction is slow