Reduction of Benzophenone to Produce Benzhydrol and Study It’s Properties

Experiment 4. Reduction of a Ketone

Objective: Reduction of benzophenone to produce benzhydrol and study it’s properties.

Equation:

Procedure: Procedure was carried out as written in the literature.1 during purification of the products by mixed-solvent recrystallization, 6mL of methanol was added. Then the solution was refluxed and then by using Pasteur pipette 3.0 mL of water was added drop by drop. Then, 1mL of methanol was added and the solution was refluxed again. This step was repeated twice for a total of 8 mL of methanol added.

Table 1. Reagants used in the preparation of an alcohol from a ketone

Compound

MW g/mol

Used

Moles

Physical Data/Safety Data

Sodium Borohydride NaBH4

37.83

.1135

3.0 x 10-3

mp: >300oC, Toxic, corrosive. Hygroscopic (close container as soon as possible). Contact with H2O liberates flammable gas. Consult instructor about disposal if necessary.

Benzophenone C13H10O

182.2

1.093

5.9 x 10-3

Bp: 305oC, mp range: 47-57oC. may be harmful if inhaled, if absorbed through skin, if swallowed causes eye irritation.

Hydrochloric Acid,

HCl

36.46

10mL

0.329 mol

D: 1.2 g/mL; Bp: > 100oC; mp: -30oC. Highly toxic, corrosive. Recycle elements if possible or dispose as directed.

Methanol

31.04

8mL

0.198 mol

D: 0.791 g/mL, bp: 64.7oC. Flammable liquid, toxic. Dispose as non-Halogenated waste.

Isoproanol,

CH3CH(OH)CH3

60.10

15mL

Solvent, 0.197

D: 0.790 g/mL, bp: 64.7oC.Flammable liquid, toxic. Dispose as non-Halogenated waste.

Nujol,(mineral oil)

-

-

-

D: 0.838 g/mL. Dispose as non-Halogenated waste.

Water, H2O

18.016

3.

D: 1.00 g/mL. Dispose as non-halogenated waste.

Table 2. Product for preparation of an alcohol from a ketone

Compound

MW g/mL

Isolated

Moles

Percent Yield

Physical/Safety Data

Benzhydrol,

C13H12O

184.23

0.82 g

4.4509 x 10-3

74.76%

Bp; 297-298oC; mp range 65-67oC. Harmful if inhaled swallowed irritant.

Table 3. Determining Melting point

Compound

Determining melting point range

Literature melting point range

Benzhydrol, C13H12O

55oC – 64oC

65oC – 67oC

Table 4. Tabulated IR spectroscopy data for Benzhydrol Nujol Mull

Wavenumber (cm-1)

Relative Intensity

Assignment and Comment

3275

Strong

OH stretching

1493

Medium

Nujol

1455

Medium

Nujol

Table 5. Tabulated IR spectroscopy data for Benzophenone1

Wavenumber (cm-1)

Relative Intensity

Assignment and Comment

3274

Strong

sp C-H stretching

3272

Strong

sp C-H stretching

3270