I&EC REPORTS
Left, shear strength, parallel to grain.
Right, static bending strength.
For sugar maple, imfiregnation with 56% fiolyvinyl acetate decreased dimensional change from water absorption about 50y0 12
= white pine-PMMA;
circular array of 9 pencils, but later a 10,000-curie source in the form of 40 pencils arranged in two rows was used. Samples were weighed and then placed in a vessel to which vacuum was applied for a time. Monomer was introduced and samples were allowed to soak under atmospheric pressure. At first, an air atmosphere was used, but later this was replaced with nitrogen. Samples were then wrapped in aluminum foil to retard evaporation, weighed. and irradiated until polymerization \vas complete. Commercial Aspects. T o put the process into commercial operation, special concerns to do the irradiation as a service to fabricators will have to be set up. ,4 moderate facility would cost a n estimated $1 million for initial capital investment, and a big installation, several million. The cobalt-60 costs about 50 cents per curie, and to set up a service would require several hundred thousand to a million curies. Half life of the cobalt is 5.2 years which means that about 121/2% would have to be replaced each year. Dosage varies, depending on monomer and wood, from l , ' ~to 5 megarads which means 1 to 2 cents per pound. Cost of monomer would also varl-. For example, methyl methacrylate costs about 25 cents per pound, and vinyl acetate about 15 cents. The development program for tailor-making wood to predetermined specifications, initiated two
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
A
=
birch-PMMA;
u
=
birch-PVA
years ago at the University of West Virginia, is sponsored by the U. S. -4tomic Energy Commission. Brookhaven National Laboratories did similar work in the early fifties, and the Russians, five or six years ago. But none was as successful as this program which mal- well mark the beginning of a srronger competitive status of wood t's. synthetic materials and alloys. Although the process has not yet been proved economically feasible, it is certain that more treated woods will appear in the next decade. According to the ,4EC, the number of requests it has received for additional details has been beyond E . KELLER expectation.
DOMESTIC PRODUCTION OF ORGANOTINS ANNOUNCED
These comparaticely new but interesting compounds are promising for a wide variety of uses ranging from plasticizers and industrial biocides to sfiecijic uses in chemotherapy The announcement by Chas. Pfizer Br Co., Inc., that, beginning February 1, it is marketing a line of organotin compounds is expected to spark the interest of other foreign and domestic chemical producers. A sizable influx of other companies into this field, long dominated by M S: T Chemicals, Inc., should depress prices which have long remained a t premium levels. (Continued on page 14)
How can vou use this propertv of FREON" fluorocarbons? IMMISCIBILITY WITH WATER is a property of the entire family of FREON
MAIL COUPON FOR TECHNICAL BOOKLET
fluorocarbons-each of which has a specific boiling point lying between +199.0° and -198.4"F! So whatever the operating temperature of your process, there's a FREON that might be valuable for liquid or vapor-phase extractions and separations. There are other properties that also apply to all FREON compounds regardless of boiling point: 1. Selective solvency 2. High thermal and chemical stability 3. Nonflammability 4. Low toxicity
5. Outstanding dielectric properties 6. Low surface tension 7. Low viscosity 8. High density
Have you an idea where any of this unique family of chemicals could be fluorocarbons are used? We'll help you develop it if you do! Clue: FREON used today as refrigerants, aerosol propellents, foam blowing agents, solvents, dielectrics, heat-transfer media, polymer intermediates and aerospace products. First step-send the coupon for complete technical information about the FREONfluorocarbon with the boiling point you want.
Du Pont,
first in fluorocerbons since 1931
Du Pont Company FREON Products Division
N-2420 1C-3R Wilmington 98, Delaware
I I
I I I I I I I I I I I I
FREON" @KDI
fluorocarbons . U Y I? M d -~ BETTER THINGS FOR BETTER LIVING , THROUGH CHEMfSTRY Circle No. 44 on Readers' Sprvirp nard
..
What boiling points are you interested in?
Any particular uses in mind?
Name
Title Company of Institution Address
Set it. ..and forget it! Automatic controls “read” the gauges that measure pressure, flow and cake thickness. Then, when the pressure becomes excessive, the flow is insufficient or the cake has reached its maximum thickness, the filter stops, cleans and precoats itself and starts the filtering cycle all over again. Filter control is positive and, there’s a new measure of precision Aexibility and efficiency because human judgment errors are eliminated, For a complete analysis of your filtration needs, send us data on your problems today. Then, ask for bulletin NC457 for details about other Niagara filters or see the Chemical Engineering Catalog for location of nearest sales representative.
I&EC REPORTS The organotins, trademarked Stan-Guard, are now produced in this country by Chas. Pfizer & Co., Inc., under a licensing agreement with Pure Chemicals. The compounds include a complex dibutyltin mercaptan, two dibutyltin maleates, dibutj-ltin dilaurate, a polymeric dibutyltin maleate, and bis(tri-nbutyltin) oxide. These materials, claimed to be compatible with homoand copolymeric polyvinyl chloride resins, labile chlorine organics, and mono- and polymeric plasticizers, are expected to find uses also as esterification and polymerization catalysts, as well as industrial biocides. A basic step in preparing these organotins is an economical method of directly alkylating the metal atom. Pfizer has not revealed the details of its method except to say that it differs from the conventional use of Grignard-type materials and techniques. Pure Chemicals’ route, as sketched by its technical manager, Dr. V. Oakes, is similar to that used in Japan. The Japanese, because of a favorable labor and materials position, can use alkyl and metallic iodides to alkylate tin directly. In Pure’s method, alkyl bromides react with stannous bromide in the presence of trace amounts of iodine, an unnamed catalyst, and solvent. The catalyst may be similar to magnesium in that its action consists of a zincmetal couple and the solvent could be an ether where alkyl groups are the same as the alkyl group to be coupled to the tin. Manufacturing costs for the organotins are lowered when the spent bromides are recycled to release bromine for reuse in the formation of more alkyl bromide. For example, dibutyltin oxide-a precursor of a number of more complex organotins-can be prepared :
+ SnBrz aBu2SnBr2 Bu2SnBrz + NaOH 2BuBr
N I A G A R A FILTERS AMETEK @
A D l V l S l O N OF AMETEK, IWC. EAST M O L I N E , I L L l M Q l S
(Niagara Filters Europe: Kwakelpad 28, Alkmaar, Holland) Circle No. 36 on Readers’ Service Card
14
INDUSTRIAL A N D ENGINEERING CHEMISTRY
+
(Bu)*SnO f NaBr (Continued on Page 76)
Your inquiry will receive immediate attentinn
CUSTOM SYNTHESIS of ORGANIC INTERMEDIATES
I ’ I
When you n d an oreanic intermediate prepared by acylation in commercial or laboratory quantities, Piister Chemical Works is ready to help you. We prepare hundreds of tons of a large varietv of products by acylation ea& year, k d have the reagents apd the equipment to produce your compound rapidly and economically.
Your inquiries about acylation or -ther syntheses are invited. AU inquiries are treated confidentially and receive prompt attention. Salicylanilide is one example of the intermediates which Pfister Chemical Works produces by ACYLATION.
1-I t1stem CHEMlCBL WORKS, J
- -
IN.
Ridgefitd, New Jwsey
C l m e I#. w VI
uadm’Miit C a d
W0d.l
7300
Cast aluminum receptor; twln foulltaln heads direct automatically
EMERGENCY EYE- WASH Sensitive eye tissue can be destroyed in moments. Contamination from industrial caustics and chemicals requires instant first aid and a HAWS Emergency Eye-Wash Fountain can mean the differencebetween temporary irritation and permanent injury! Write for your free HAWS catalog.
. ..
EYE-WASH FOUNTAINS Since 1909
16
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
16EC REPORTS These organotin compounds are comparatively new but have generated a great deal of interest in the last decade. They have shown pro& as s t a b h e n in rigid polyvinyl chloride for building products and piping where resistance to weather and freedom from corrosion is important. These compounds help to preserve the clarity of a clear plastic and in no way affect the purity of a color in plastics. The high degree of reactivity of the organoh9 makes them useful for other chlorinated systems since they will readily react to “getter” degradation products in chlorinated dielectric liquids. Research is continuing in the use of tin as a polymerization catalyst for cross-linking or as in integral part of the substituent monomer. Another important and growing use for these compounds is in industrial microbial control. For sometime, tributyltins have been used to eliminate fungi which accumulate in papermaking machinery; more recently, bis(tributy1tin) oxide has been used to control microbial growth in water-cooling and air conditioningsystems. Bis(tributy1tin) oxide and its derivatives are also valuable as fungicides in marine and household paints. Their use is being investigated as an economical termite repellant to substitute for the more expensive pentachlorophenol and chlordane. The potential of the materials as bacteriocides has been demonstrated against gram-positive bacteria in hospital l i e n s and baby diapers. Spray formulations of some of these organotins are reported to have successfully combated airborne staphylococci. One of the most important potential uses for bis(tributy1tin) oxide is its ability to combat schistmmiasis. This disease spread by snails is endemic to the world’s tropical belt and is currently a problem being investigated by the World Health L. mmmm Organization.
