What's in a Medicine - Phenols and Salicylic Acid

Question 1

what are the 3 different environments that hydroxy groups can be found in organic molecuels?

Answer 1

carboxyl group in carboxylic acids

attached to alkane in alcohols

attached to benzene rings in phenols

Question 2

what is the order of acid strength in:

water

phenol

carboxylic acids

ethanol

Answer 2

ethanol

water

phenol

carboxylic acid

Question 3

draw the structure of phenol

Answer 3

Question 4

write the general equation for hydroxy groups dissociating in water

Answer 4

Question 5

what are the tests to determine between carboxylic acids, phenols and alcohols?

Answer 5

carboxylic acids and phenols react with NaOH to form sodium salts

carboxylic acids react with carbonates - fizzing observed

alcohols react with neither

Question 6

describe the iron(III) chloride test for phenols

Answer 6

phenol forms a purple complex with the iron ions in neutral solution

Question 7

can phenols form esters and why?

Answer 7

no

do not react with carboxylic acids

Question 8

what is salicylic acid’s structural name?

Answer 8

2-hydroxybenzoic acid

Question 9

draw salicylic acid

Answer 9

Question 10

how is aspirin formed?

Answer 10

esterification of salicylic acid

Question 11

draw the structure of aspirin

Answer 11

Question 12

what are the two ways of esterifying salicylic acid?

Answer 12

reacting the hydroxy group with an acid anhydride

reacting the carboxyl group with an alcohol

Question 13

when salicylic acid is reacted with methanol, what is produced?

Answer 13

methyl 2-hydroxybenzoic acid

also well known as oil of wintergreen

Question 14

what is the solubility of oil of wintergreen?

Answer 14

soluble in fats, not water

Question 15

what is the use of oil of wintergreen?

Answer 15

absorbed through the skin

helps reduce pain and swelling

Question 16

what is the product of reacting the hydroxy group of salicylic acid with an acid anhydride?

Answer 16

aspirin

Question 17

what is the structural name of aspirin?

Answer 17

2-ethanoyloxybenzoic acid

Question 18

what is the solubility of aspirin?

Answer 18

soluble in water

Question 19

how does aspirin being soluble in water help it to reduce pain and swelling?

Answer 19

can be absorbed into bloodstream through stomach wall

Question 20

what are the techniques for purifying organic solids?

Answer 20

recrystallisation

thin layer chromatography

melting point determination

Question 21

describe the process of recrystallisation

Answer 21

derised compound dissolved in a hot solvent

insoluble impurities are filtered off

upon cooling, the desired compound will crystallise out, leaving the soluble impurities in solution

pure crystals filtered out, washed and dried

Question 22

describe the process of thin layer chromatography

Answer 22

normal chromatography but with a silica plate

compare substance to pure and impure samples to determine it’s purity

Question 23

describe the process of melting point determination

Answer 23

melt sample and compare to published value of melting point

a pure substance should be within 0.5ºC