Question

1. A student carries out an esterification reaction where he used 1.5 mL of butyric acid and 1.0 mL of methanol. Obtained 1.0 mL of product. Calculate the theoretical yield and% yield (from grams of product).

2. What are the reaction conditions that favor the SN2 mechanism in the

laboratory?

3. What are the reaction conditions that favor the SN1 mechanism in the

laboratory?

4. What property do low molecular weight esters have?

PLEASE ANSWER ALL THE QUESTIONS AND DON'T WRITE THE ANSWERS ON A PAPER. THANKS!

Answer 1

Ans:

1 Butyric acid + 1 Methanol ---> 1 methyl butyrate

Butyric acid and methanol react in 1:1 ratio to form 1 mol of ester

	Molecular mass, M	Volume taken, V	Density,d = mass/V	Mass, w = d x V	Mole, n = w/M
Butyric acid C4H8O2	88.11 g/mol	1.5 mL	0.9528 g/mL	1.4292 g	0.0162 Limiting reagent
Methanol CH3OH	32.04 g/mol	1.0 mL	0.792 g/mL	0.792 g	0.0247
Methyl butyrate C5H10O2	102.13 g/mol	1.0 mL (obtained)	0.898 g/mL	0.898 g (yield obtained)	0.0088 (obtained)

Here Butyric acid is the limiting reagent.

In a reaction limiting reagent is completely consumed. So, 0.0162 mol of butyric acid is expected to give 0.0162 mol of methyl butyrate.

Yield expected (theoretical yield) = 0.0162 x 102.13 = 1.6545 g

% yield = yield obtained/theoretical yield = (0.898/1.6545)x100= 54.28 %

Ans 2 & 3:

Conditions favoring SN1	Conditions favoring SN2
Tertiary alkyl halides are better reactants	Primary alkyl halides are better reactants
A weak nucleophile (neutral nucleophile) is a better choice	A strong nucleophile (negatively charged nucleophile) is a better choice
Polar protic solvents like H2O, alcohol helps	Polar aprotic solvents like DMF, DMSO helps
Higher concentration of alkyl halide increases the rate	Higher concentration of alkyl halide & nucleophile increases the rate

Ans 4:

Low molecular weight esters:

• Have pleasant smell, so are used in fragrances and essential oils.
• They are more flexible and have low polarity (in comparison to amides of comparable mass).
• Have lower melting point and more volatile (in comparison to amides of comparable mass)
• Are slightly soluble in water because of their capacity to form H-bonding.