'Five Senses to the Rescue'

In troubleshooting one must never forget the portable laboratory equipment that one carries around—the senses of sight, sound, scent, taste and touch. There is also the common sense that stops one tasting things if there is any cyanide about. Long years ago the Deutsche Hydriewerke started marketing non-soapy detergents of the cetyl or oleyl sulfate variety. Prior to World War II, the British textile industry was as dependent on German supplies of these materials as it had been on German d

January 12, 1987

In troubleshooting one must never forget the portable laboratory equipment that one carries around—the senses of sight, sound, scent, taste and touch. There is also the common sense that stops one tasting things if there is any cyanide about.

Long years ago the Deutsche Hydriewerke started marketing non-soapy detergents of the cetyl or oleyl sulfate variety. Prior to World War II, the British textile industry was as dependent on German supplies of these materials as it had been on German dyestuffs prior to World War I.

Foreseeing what was going to happen, I started in 1936 to work out a process for making cetyl, stearyl and oleyl alcohols, taking the head oil of the sperm whale as a starting point. The sperm whale's body oil differs but little from that of any other whale. The so-called head oil, however, is not an oil at all but a liquid wax; that is to say an ester of a higher aliphatic alcohol with a higher aliphatic acid, cetyl oleate or oleyl pahnitate being typical components.

It sounds simple to hydrolyze such materials and extract the alcohols from the soaps with a solvent. But the resulting mush of soap, solvent and fatty alcohol proved to be an unbreakable emulsion that was simply unextractable. I therefore had the idea of saponifying the wax and steam distilling the alcohols out of it.

Briefly, one heated the liquid wax up to a temperature of nearly 200°C and then ran in 50 percent caustic soda lye very slowly so that the aqueous component of the lye flashed off the surface of the liquid wax, allowing the caustic soda to react with it simultaneously, thereby producing a mixture of fused anhydrous soap and fatty alcohols.

After distilling out the alcohols, the fused anhydrous soap was tapped off into boiling 50 percent sulfuric acid in a lead-lined vat, which decomposed it into mixed fatty acids and a sodium sulfate solution that joined the rest of the factory effluent.

There was an element of anxiety in this due to some sulphuric spray and an output of sulphur dioxide, both to the atmosphere. The prevailing wind, however, first carried them across half a mile of wasteland and then across two miles of the Mersey estuary. Observation of the flora over a couple of years didn't indicate any adverse effects and I heard nothing from the Inspector of Nuisances, although I suppose that today I would not be allowed to get away with it. There remained the fatty acids. After vacuum distifiation, they proved a perfect feed-stock for shaving soap. Multiple birds were thus killed with one stone!

I worked the process up from a one-pound still in the lab to a 100-pound still in the works and then scaled it up sequentially to a 25-hundredweight still and finally to a 10-ton still.

The first difficulty was "priming." If one didn't get conditions exactly right when adding the caustic soda, the contents of the still primed over into the condensers and blocked them. They then had to be dismantled and the cold anhydrous soaps chipped out.

Anhydrous soap is as hard as a brick! Old-fashioned kitchen soap is about 36 percent water. Toilet soap is about 15 percent water. Neither compares in any way with the anhydrous variety, which is a nightmare.

Sometimes the process worked perfectly. Sometimes it primed—often enough to drive me to despair. What was the condition or combination of conditions that controlled its working or not working? The variables at my disposal were the temperature and the rate of addition of caustic soda, but varying these systematically didn't lead me to a cure.

What was going on inside that still? One way of answering that question is to listen. There is a primitive way of listening to what goes on inside the shell of a chemical reactor. This consists of pressing the tip of a pencil against the metallic shell and the other end of the pencil against one's mastoid bone. Using this technique I heard a lot of crackling going on and supposed it might be water evaporating (though oil is not soluble in water, water is soluble in oil up to about one percent). But the crackling was manifest at temperatures well above the boiling point of water. The temperature at which it set in was variable and so was the temperature at which it ceased.

In the result it transpired that once the crackling had ceased it was safe to add the caustic soda. I never discovered what caused the crackling, but I had a process that worked reliably thereafter. My old master, Dr. W H. Hatfield, F.R.S., used to say that the saving grace of technology is that you can make a process work without knowing why. The foregoing is a good example.

The next problem was to separate the cetyl and oleyl alcohols from one another, for they are used in different contexts.

I tried cooling the mixtures in pans in the hope of sweating the liquid oleyl out of the solid cetyl alcohol by the process used in the paraffin wax industry. No go! I tried pressing them by the process used in the fatty acid industry, in which the oleic acid is literally squeezed out of what is called an open crystal cake in which the solids are maintained in the ratio of 55 percent palmitic acid to 45 percent stearic acid. Very large acicular crystals are formed under these conditions, and the liquid oleic acid can be readily expressed from them. My fatty alcohols refused to oblige! They formed nothing more than a cheesy mixture that spewed all over the place.

"It's extraordinary," I said rather gloomily to the chargehand who was handling some fully loaded pans of crystalizing alcohols. "The liquid is sweating out all over the surface. Look!" I rubbed the surface with my middle finger and showed it to him covered with an oily film. "If it sweats like that naturally there must be a way of accelerating it!" I searched for a handkerchief to rub the oily film off my finger and, failing to find one, licked it off with my tongue. A burning sweet taste rewarded me. "Good Lord! It's not oleyl alcohol; it's crude glycerol! That's what's been closing the structure."

The sperm head oil was probably contaminated in storage by its body oil or other whale oils and when we saponified the waxes we saponified the glycerides too and the glycerol distilled over with the fatty alcohols.

We immediately melted whatever we had available, boiled it up on open steam, and had beautifully pressable crystals by breakfast. Once more, five senses to the rescue!

Lord Halsbury is a fellow of the Royal Society and chancellor of
Brunel University, Uxbridge, United Kingdom UB8 3PH.

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