core practical 16: preparation of aspirin

Question 1

aspirin melting tempertaure

Answer 1

136 degrees

Question 2

method

Answer 2

• add 2-hydroxy benozoic acid and ethanoic anhydride to a pear shaped flask
• add a few drops of conc sulfuric acid
• fit the flask with a condenser, and heat in a boiling water bath for 5 mins, warm and swirl until all solid has dissolved
• remove flask from hot water bath, pour into beaker, add cold water and ice to BREAK DOWN ETHANOIC ANYHDRIDE
• stand in ice bath to complete filtration
• buchner filter
• recrystallise
• determine bp, compare to data book value

Question 3

describe bp if not pure; a mixture?

Answer 3

• lower mp
• will melt over a range

Question 4

what to use to determine bp

Answer 4

• thiele tube
• dibutyl phthalate as
• higher bp than sample, low flammability