C a t ~ i i r s y01 Shell Chrmicul C~rpor,~iion
Synthetic Glycerol Plant. Houston. Texas
ELBERT C. WEAVER
Phillips Academy, Andover, Massachusetts
IF
YOUR stndents in elementary organic chemistry should represent the addition of chlorine to propylene as
CH*>CHCHa
+ CI,
-
CH2=CH.CH2CI
+ HCI
showing the formation of allyl chloride, you might mark this atypical equation as incorrect. Nevertheles~,the reaction is the first step in a successful commercial synthesis of glycerol. In t,his process, flow rate, temperature, and pressure are carefully controlled. Many years of investigation were needed to bring this reaction into the rage of commercial practicability. Now a plant is in operation that produces glycerol from hydrocarbons. The second and third steps of this process, carried out simultaneously, include complete chlorination of allyl chloride to trichloropropane and the replacement of halogen by the hydroxyl group, which in turn is derived from sodium hydroxide solution in water solution.
OCTOBER, 1952 The cor~versiontakes place under controlled conditions of pH, flow rate, temperature, and time. The dilute solution of glyccrol and common salt is cvaporatcd and tlcs:rltcd. The glycesol is rccovered by distillation under rcduccd pressure. After other stcps of purification, the glycerol comes to thc market 99 per cent pure. Over 1500 uses of glycerol are known in the arts, hut today t,hree major uscs arcount for the principal applications. Explosives, cellophane, and alkyd resins are the major outlets today. Even ten years ago, the manufarture of alkyd resins was the princibal use of glycerol. Over 40 million pounds were consumed for the purpose. Glycerol imparts flexibility and toughness t,o cellophane, which otherlvise would be a brittle and unsatishctory wrapping material. The use of glycerol in t,he mnriufactt~reof' explosives is well known. The total demand is in excess of 200 million pounds for all uses, tl demand that codd not he met from the familiar source, t,he hy-pmdurt of saponificat,inn of fat,s, alone.
Pmtiom of A l b l Chloride Synthesis Unit.
CH-CH
.CH&I
+ CIS
Here AUyl Chloride is Mado Chlorine.
--
fro." F'ropyleno .nd
CHzCI.CITCI.CIICI t. 3NaOI.T
CH&I .CHCI .CH,CI
+ 3NaCI
C8Hs(OH)3
