Organic Chemistry Answers

during recrystallization:


1) why activated charcoal is used?

2) why solution should not immediately placed in ice bath after hot filtration/

3) why not 50% of boiling solvent was added to solute to prevent premature crystalization?

4) why not large amount of charcoal is used?

Why is acetic acid more soluble than benzoic acid in water? (Hint: What structural features does a molecule need to able to be soluble in water? Refer to relevant intermolecular forces.)

Methyl salicylate, C8H8O3, is the chemical responsible for wintergreen flavouring. It can be produced by heating salicylic acid, C7H6O3, with methanol, CH3OH.


This image shows C sub 7 H sub 6 O sub 3 + CH sub 3 OH, reaction arrow, C sub 8 H sub 8 O sub 3 + H sub 2 O.


An organic chemist reacts 6.70 g of salicylic acid with excess ethanol to produce 5.80 g of methyl salicylate.


What is the theoretical yield?

a) (i) Use EDTA structure to describe hexadentate chelating agent (2mks)

(ii) State four types of EDTA titrations (2mks)



b)ii)Consider the titration of 50mL Mg 2+ sample in a pH = 10.00 buffer with 0.05M EDTA as titrant. Calculate the amount of Mg in ppm if the titre is 5ml of EDTA (3mks)

ii) Calculate the pH of a 1000-mL buffer solution containing 0.200M NH4OH and 0.300M NH4CI. (3mks)

under which conditions can alkanes react with halogens?

A 0.10M solution of NaOH ,is used to titrate 10.00ml of 0.10M CH3COOH.

Calculate the pH at equivalence point (3mks)

b) Sketch the titration curve in (a) above. (2mks)

c) Consider the titration of 25mL of 0.1M KCI with 0.050M AgNO3 using the Mohr method and given Ksp (AgCl) = 1.8 xl 0-10


Name the indicator used for the Mohr method. (1mk)

Use equations to explain how the end point is detected using this indicator.

Coverson


Acetadihyde from 1,2 dibromobutane

Treatment of cyclopentane-1,3-dione with a base followed by addition of methyl iodide affords a mixture of 2-methylcyclopentane-1,3-dione, 2,3-dimethylcyclopentane-1,3-dione and 3-methoxy-2-cyclopenten-1-one. Explain with the aid of mechanism how each product is formed

Treatment of cyclopentane-1,3-dione with a base followed by addition of

methyl iodide affords a mixture of 2-methylcyclopentane-1,3-dione, 2,3-

dimethylcyclopentane-1,3-dione and 3-methoxy-2-cyclopenten-1-one.

Explain with the aid of mechanism how each product is formed

Phenol undergoes electrophilic aromatic substitution with nitric acid and sulfuric acid to afford a mixture rich in o- and p-nitrophenols. Write a mechanism that accounts for the selective formation of these products - include electrophile formation as well as addition to the phenol.