Elementary (Hive Addict)
05-28-02 09:43
No 315240
      Pyrolysis (Dry Distillation) Q's  Bookmark   

Swim wants to make some acetophenone from calcium benzoate and calcium acetate but is not sure what conditions this reaction needs.

Can this be performed in pyrex gassware ?

Does the pyrolysis need to be conducted under vacuum or in an inert atmosphere (nitrogen) ?

What sort of temperatures are needed ?

John Lennon - Working Class Hero
(Master Searcher)
05-28-02 15:29
No 315325
      sodium acetate  Bookmark   

Fused sodium acetate facilitates the process.  If you make the calcium salts use CaO or Ca(OH)2, not CaCO3.  CaCO3 reacts too slow.

From 'Experimental Organic Chemistry' by J. F. Norris
copyright 1933 pages 95-96

Formation of Acetone from an Acetate

Place in an 8-inch test-tube 7 grams of calcium acetate and 7 grams of anhydrous
sodium acetate which have been intimately mixed by grinding together in a mortar.
Clamp the tube in a horizontal position and connect it with a condenser.  Tap
the tube gently so that a channel is formed along its whole length.  Heat until
the acetates glow, turning the tube from time to time, so that all of the salts
can be heated to a high temperature.  Redistil the liquid and determine its
Acetone boils at 56 degrees C.  The yield is from 3 to 4 grams.

Note.--Sodium acetate is mixed with calcium acetate in this preparation in order
to facilitate the formation of acetone.

Note at the bottom of page 50 on how to make fused sodium acetate:

Commercial fused sodium acetate is generally not anhydrous; it is well to fuse it
before use.  If the compound is to be prepared from the hydrated salt
(CH3COONa.3H2O)  proceed as follows:  Heat cautiously about 15 grams of the
crystalline salt contained in an iron pan over a small flame.  Stir continuously
with a glass rod.  The salt melts at first in its water of crystallization; as
the dehydration proceeds it solidifies, and, finally, when anhydrous, melts a
second time.  Care should be taken to avoid heating the dehydrated salt much
above its melting-point, as it undergoes decomposition when strongly heated.

The hardest thing to explain is the obvious