Aromatic compounds & Carbonyls

Question 1

how do you make an ester ?

Answer 1

react an alcohol with a carboxylic acid or a carboxylic acid derivative

Question 2

what is a carboxylic acid derivative ?

Answer 2

substance made from carboxylic acid (like an acyl chloride)

Question 3

how do you name an ester ?

Answer 3

first part of name - alkyl group

second part - carboxylic acid group, but ‘oate’ replaces ‘oic acid’

Question 4

what is an esterification reaction ?

Answer 4

reversible reaction between alcohol and carboxylic acid to make an ester

Question 5

what is needed for an esterification reaction ?

Answer 5

heated / concentrated sulfuric acid catalyst

Question 6

as an esterification reaction is reversible, what must you do…

Answer 6

separate the product as its formed

Question 7

describe esterification reaction for small esters

Answer 7

warm (product) mixture to distil off the ester as is more volatile than other compounds

Question 8

define volatile

Answer 8

easily evaporated

Question 9

what else is produced in esterification reaction

Answer 9

water

Question 10

what type of reaction is an esterification reaction

Answer 10

condensation reaction

Question 11

describe esterification reaction for large esters

Answer 11

heat under reflux and use fractional distillation to separate ester from other compounds

Question 12

what is an acid anhydride ?

Answer 12

two carboxylic molecules - H20 (from condensation reaction)

Question 13

how can ester be formed from acid anhydride and alcohol ?

Answer 13

react together with heat (no catalyst)

produces ester and carboxylic acid - separate with fractional distillation

Question 14

what is the 3rd way to make an ester ?

Answer 14

alcohol + acyl chlorides, which forms and ester and HCl gas

Question 15

what are the two ways to hydorlyse esters?

Answer 15

acid hydrolysis and base hydrolysis

Question 16

what happens when you hydrolyse an ester ?

Answer 16

forms an alcohol

Question 17

Describe acid hydrolysis of an ester

Answer 17

• splits ester into carboxylic acid and an alcohol
• heat under reflux with dilute acid (HCl)
• reversible reaction so lots of water needed

Question 18

Describe base hydrolysis of an ester

Answer 18

• splits ester into carboxylate salt and alcohol

- heat under reflux with dilute alkali (NaOH)

Question 19

why is kekule’s model no longer used?

Answer 19

the model suggested that there were C=C and C-C bonds with diff. lengths, when really they are all the same length

Question 20

what 3D shape is benzene ?

Answer 20

planar (flat)

Question 21

what are compounds containing a benzene ring called ?

Answer 21

arenes / aromatic compounds

Question 22

electrons in benzene ring are …

Answer 22

delocalised

Question 23

what evidence is there for benzene being more stable than kekule’s ?

Answer 23

hydrogenation is less exothermic than expected, so more energy needed to break bonds

Question 24

what is thought to cause the stability of benzene ?

Answer 24

delocalised ring of electrons

Question 25

what does a catalyst do to a species to allow it to act as an electrophile for benzene ?

Answer 25

polarises it

Question 26

what type of reaction does benzene undergo ?

Answer 26

electrophillic substitution

Question 27

what catalyst for chlorination of benzene ?

Answer 27

anhydrous AlCl3

Question 28

what catalyst for bromination of benzene ?

Answer 28

anhydrous FeBr3

Question 29

what catalyst / reagent for nitration of benzene ?

Answer 29

conc sulfuric acid, nitric acid

Question 30

what conditions / reagents for alkylation of benzene ?

Answer 30

reflux, AlCl3 catalyst and haloalkane

Question 31

what is the non organic product of nitration of benzene ?

Answer 31

water

Question 32

what conditions / reagents for acylation of benzene ?

Answer 32

acyl chloride, reflux, AlCl3 catalyst

Question 33

why keep temp lower than 55 for nitration of benzene ?

Answer 33

to get only one substitution

Question 34

why is phenol more reactive than benzene ?

Answer 34

- lone pair on oxygen partially delocalises into electron ring - increases electron density - more likely to be attacked by electrophiles

Question 35

what are some electron donating groups ?

Answer 35

OH-, NH2-

Question 36

what positions for electron donating groups ?

Answer 36

2, 4, 6

Question 37

what are some electron withdrawing groups ?

Answer 37

NO2+

Question 38

what are the positions for electron withdrawing groups ?

Answer 38

3, 5

Question 39

what is formed from reaction between bromine water and phenol ?

Answer 39

2,4,6-tribromophenol and hydrogen bromide

Question 40

what is formed from the nitration of phenol ?

Answer 40

2 isomers of nitrophenol (at position 2 / 4) | water

Question 41

what is needed for the nitration of phenol ?

Answer 41

just dilute nitric acid

Question 42

what about phenol means it can undergo typical acid-base reactions ?

Answer 42

it is weakly acidic

Question 43

what is the formula for acidified potassium dichromate ?

Answer 43

K2Cr2O7 / H2SO4

Question 44

state the test for carboxylic acids

Answer 44

add sodium carbonate | effervescence shows positive test

Question 45

what is the product formed from carboxylic acid test ?

Answer 45

carboxylate salt

Question 46

what type of reaction is carboxylic acid test ?

Answer 46

acid - base

Question 47

state the test for alkenes

Answer 47

add bromine water | orange colour decolourises

Question 48

state the test for phenols

Answer 48

add bromine water | orange decolourises and white ppt forms

Question 49

what type of reaction is test for phenol?

Answer 49

electrophillic substitution

Question 50

state the test for aldehydes

Answer 50

add ammonical silver nitrate solution (tollens) | silver mirror will form

Question 51

what product is formed in tollens ?

Answer 51

carboxylic acid

Question 52

what type of reaction is tollens ?

Answer 52

oxidation

Question 53

state the test for aldehydes and ketones

Answer 53

2,4-DNPH (Brady's) | orange ppt will form from orange solution

Question 54

what type of reaction is Brady's ?

Answer 54

condensation

Question 55

what reagent is used in the reduction of carbonyls ?

Answer 55

NaBH4

Question 56

what type of mechanism is reduction of carbonyls ?

Answer 56

nucleophillic addition

Question 57

what to remember with reduction of carbonyls ?

Answer 57

2 [H]

Question 58

describe how hydrogen cyanide (HCN) reacts w/ carbonyls

Answer 58

dissociates to H+ and CN- nucleophillic addition occurs w/ CN- as nucleophile hydroxynitirle formed

Question 59

what makes carboxylic acids so soluble ?

Answer 59

form H bonds with water

Question 60

how do you name an acyl chloride ?

Answer 60

-oyl chloride

Question 61

how are acyl chlorides formed ? (give products too)

Answer 61

carboxylic acid + SOCl2 --- acyl chloride + SO2 + HCl

Question 62

what substances do acyl chlorides react w/ and lose their chlorine ?

Answer 62

cold water / alcohol / ammonia / amine / phenol

Question 63

when acyl chloride reacts and loses chlorine, what is ALWAYS formed ?

Answer 63

HCl gas

Question 64

why are electron donating groups 2,4,6 directing ?

Answer 64

- electrons delocalise into ring, increasing electron density - greater electron density at 2,4,6 carbons so more attracted to electrophiles

Question 65

why are electron withdrawing groups 3,5 directing ?

Answer 65

- withdraws electrons from ring, decreasing electron density - withdraws electron density from 2,4,6 so unlikely to react w/ these positions