Question

Propyl Benzhydryl Ether (continued on next page):

(1) What volume of 1-pentanol is needed to convert 1.50 grams of benzhydrol to n-pentyl benzhydryl ether?
(2) Based on the results of this experiment, write a mechanism for the acid catalyzed reaction of benzhydrol with 1-pentanol to give the product from the last question. (Note: the mechanism is written on the first page of this experiment. You just have to figure out, based on the experimental results, which alcohol is ROH and which is R'OH and the write it using those two alcohols.)
(3) Under milder temperatures than what is needed for dehydration, strong acids catalyze the self-condensation of 1-propyl alcohol to give di-n-propyl ether. The mechanism differs from that of today's reaction in that the protonated alcohol undergoes an Sy2 rather than an Syl reaction. Write the mechanism for the acid catalyzed condensation of ethyl alcohol to give diethyl ether. Note: make sure your mechanism has the following three steps (a) protonation (b) Sx2 (not Syl) and finally (c) deprotonation.

Answer 1

See detailed explanation and image attached

Step-by-step explanation:

1 mole of 1-pentanol reacts with 1 mole of benzhydrol

Number of moles in 1.5 g of benzhydrol = mass/molar mass = 1.5 g/184 g/mol = 0.008 moles of benzhydrol

x moles of 1-pentanol reacts with 0.008 moles of benzhydrol

x = 0.008 moles of 1-pentanol

If 1 mole occupies 22.4 L

0.008 moles occupies 22.4 * 0.008 moles = 0.179 L of 1-pentanol is required.

The mechanism of the formation of n-pentyl benzhydryl ether involves the protonation of the -OH group in benzhydrol. This is followed by loss of water molecule creating a carbocation which is attacked by the 1-pentanol. Abstraction of a proton by a base completes the mechanism, regenerates the acid and yields the n-pentyl benzhydryl ether as shown in the image attached.

The synthesis of diethyl ether occurs by protonation of one ethanol molecule followed by SN2 attack by anothe ethanol molecule and a simultaneous loss of a water molecule. Deprotonation by a base yields the diethyl ether