Page 40 - Chemical and process design handbook

Speight_Part 1_H 11/7/01 3:03 PM Page 1.26

1.26 REACTION TYPES
1. A sulfuric acid process similar to the one described for ethanol hydration
2. A gas-phase hydration using a fixed-bed-supported phosphoric acid
catalyst
3. A mixed-phase reaction using a cation exchange resin catalyst
4. A liquid-phase hydration in the presence of a dissolved tungsten catalyst

The last three processes (2, 3, and 4) are all essentially direct hydration
processes.

CH CH=CH + H O → CH CHOHCH 3
3
2
3
2
Per-pass conversions vary from a low of 5 to a high of 70 percent for the
gas-phase reaction.
Secondary butanol (CH CH CHOHCH ) is manufactured by processes
3 2 3
similar to those described for ethylene and propylene.
Hydrolysis usually refers to the replacement of a sulfonic group (–SO H)
3
or a chloro group (–Cl) with an hydroxyl group (–OH) and is usually accom-
plished by fusion with alkali. Hydrolysis uses a far wider range of reagents
and operating conditions than most chemical conversion processes.
Polysubstituted molecules may be hydrolyzed with less drastic condi-
tions. Enzymes, acids, or sometimes water can also bring about hydrolysis
alone.
ArSO Na + 2NaOH → ArONa + Na SO + H O
3 2 3 2
ArCl + 2NaOH → ArONa + NaCl + H O
2
Acidification will give the hydroxyl compound (ArOH). Most hydrolysis
reactions are modestly exothermic.
The more efficient route via cumene has superceded the fusion of ben-
zene sulfonic acid with caustic soda for the manufacture of phenol, and the
hydrolysis of chlorobenzene to phenol requires far more drastic conditions
and is no longer competitive. Ethylene chlorohydrin can be hydrolyzed to
glycol with aqueous sodium carbonate.
ClCH CH OH → HOCH CH OH
2
2
2
2
Cast-iron or steel open fusion pots heated to the high temperatures
o
required (200 to 325 C) with oil, electricity, or directly with gas, are stan-
dard equipment.