Question

Based on the reaction written on paper, answer the following:

a) What is the theoretical yield?

b)What were the limiting reactants? Mechanism? Were there any by-products or side products?

c) Which is the organic layer? What is the relative ratio of products or reactants?

d) Label all peaks on the NMR. Tell how splitting patterns and integrations support the product structure. Find the integration values.

e) Draw a separation scheme for this reaction. (does not need to be too long)

me thanol & water & tert-Butylbromide. CH3 Cast Bor CH3OH IAL CH₂ Choling H2O int CH3 0.4mL 30 min. (No hart) und was air condenser and Glass ware setup 5m2 val. Expected product : CH3 CH3 H. OHH OCH CH3 CH3 T but anol and - betyl methyl ether

Answer 1

1.a) What is the theoretical yield ?

Answer: Tertiary butyl bromide on reaction with methanol in water media gives tertiary butyl methyl ester.

Density of Tertiary butyl bromide = 1.22 g/mL

So weight of Tertiary butyl bromide = 1.22 * 0.4 = 0.488 g.

Molecular weigh of Tertiary butyl bromide = 137.02 g ( 1 mole )

Molecular weigh of Tertiary butyl methyl ester.= 88.15 g. ( 1 mole )

one mole of reactant will give one mole of product theoretically.

So, 0.488 g of Tertiary butyl bromide gives = 0.488*88.15/137.02 = 0.31 g of tertiary butyl methyl ester.

Hence, 0.31g is theoretical yield.

b)What were the limiting reactants? Mechanism? Were there any by-products or side products?

Answer: Limiting reactant is a substance which is totally consumed in the reaction. The amount of product formed is determined based on the quantity of limiting agent. In this reaction tertiary butyl bromide is limiting agent as it is used in fixed quantity. water and methanol are used in the excess with respect to tertiary butyl bromide.

Mechanism:

The reaction follows SN1 reaction. In first step there is formation of tertiary carbocation which determines rate of reaction. in second step methanol reacts with carbocation to form tertiary butyl methyl ester

Tertiary butanol and 2-methyl-1-propene are possible side product. but there is no heating condition so possibility of 2-methyl-1-propene is rare under experimental condition.

c) Which is the organic layer? What is the relative ratio of products or reactants?

Answer: tertiary butyl methyl ester is the organic layer. It is upper layer as density of tertiary butyl methyl ester is 0.7404 g/mL

d. Label all peaks on the NMR. Tell how splitting patterns and integrations support the product structure. Find the integration values.

Answer: peak intensity of 5.67 at 3.21 ppm is of methyl group of methoxy functional. As methyl is attached to electro negative oxygen aton, the peak will observed around 3 - 4 ppm , the exact ppm value depends on the group attached to the vicinity of methoxy group. The peak will observe as single peak as there are no hydrogen atom to the adjacent atom. The peak at 1.2 ppm is of three methyl group, the single peak will observe for all methyl group as they are having same equivalent and have same chemical envirnoment with respect to tertiary carbon to which it is attached.

e. Draw scheme for reaction: