Experimental
Synthesis of benzyl alcohol and benzoic acid
1. Experimental Purposes
(1) To have a good command of the method and principle of Cannizarro´s reaction
(2) To know other preparative methods of benzyl alcohol and benzoic acid
(3) To know chief uses of benzyl alcohol and benzoic acid
(4) To master separate-pure method and pure mensuration for organic solid and liquid
compounds
2. Experimental Principles
——aldehyde without α-H
benzyl alcohol: perfume
benzoic acid: preservative
The physical and chemical characters of the chief reagents
apellation
benzaldeh
yde
benzyl
alcohol
benzoic
acid
Molecular
weight
modality
106.13
Achromaticity
liquid
108.15
Achromaticity
liquid
122.13
White crystal
specific
gravity
1.0415
1.0419
1.2659
melting
point
-26
-15.3
122.4
3. Main apparatus and chemical reagents
boiling
point
178.1
205.35
249
refractive
index
dissolvability
1.5463
Slightly dissolve
in water, dissolve
in ethanol, aether，
acetone
1.5396
dissolve in water,
ethanol, aether，
acetone
1.504
Slightly dissolve
in water, dissolve
in hot water,
ethanol, aether，
acetone
Beaker, flask, separating funnel, distillation flask, condensator, thermometer, tap
funnel, water bath pot, balance, refraction analyzer, benzaldehyde，acther
4. Experimental Process
(Erlenmeyer flask) KOH (18g, 0.32mol), water (18mL)
cool to room
temperature, add newly braised benzaldehyde（21g,20mL,0.2mol）
placed
add water （60~70mL）
（separating funnel）
acther layer (benzyl alcohol): 10mL saturation Na2SO3
10mL 10% Na2CO3
24h（eraser stopple）
aether（20mL） extractions
10mL water（throw water layer away）
MgSO4
braise acther in water bath
204~206℃
weight
dry with pure K2CO3 or pure
distil
calculate
collect compounds of
productivity
measure
refractive index
water layer（benzoic acid）: acidification
separate out
suction strather
calculate productivity
coolling
deposit and
recrystal with water
weight
measure melting point
5. The most important:
The separate-purify method and pure mensuration for solid compound
——recrystal, suction strather,measure melting point
The separate-purify method and pure mensuration for liquid compound
——extraction, distil, measure refractive index
6. Questions?
(1) The other synthesis method of benzyl alcohol and benzoic acid？
(2) How to separate and purify the solid compound?
(3)How to separate and purify the liquid compound