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KIRK-OTHMER ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY THIRD EDITION i -. A WILEY-INTERSCIENCE PUBUCATION w ca John Wiley & Sons 0 co NEW YORK • CHICHESTER • BRISBANE • TORONTO QD ~A

94 ANTIFREEZES AND DEICING FLUIDS 1(iRx - o7tImER, vO(l. 3 base materials can be found in standard reference books (48). The biggest hazard with ethylene glycol antifreezes is oral ingestion, particularly by children. The acute toxicity is low to moderate based on tests with several animal species. For humans, a lethal dose is about 1.4 g/kg or 100 mL for an adult. There appears to be little hazard to contact with skin or eyes if the exposure is not extensive or prolonged. Repeated or prolonged exposure to mists or heated vapors should be avoided but at ambient temperature the vapor pressure of ethylene glycol is very low. Propylene glycol has a very low single dose oral toxicity, the lethal dose for humans is estimated to be greater than a liter. Skin contact produces essentially no effect short term although dermal studies with humans indicate primary irritation can occur with some individuals, possibly due to dehydration. Skin sensitization,'however, is not in evidence and skin absorption is not likely. Eye contact does not result in irritation. Inhalation exposure to vapors and mists appears to cause no adverse effects. Both ethylene and propylene glycol are apt to enter the water environment after use. They have high solubility and low vapor pressure. They have low toxicity to fish, animal wildlife, plant life, and microorganisms. Biodegradation is fairly rapid and complete. The chief consideration is to avoid a local high concentration that could overload the mechanisms of disposal in the environment. "Antifreezes" in ECT 1st ed., Vol. 2, pp. 37-50, by D. G. Zink, U.S. Industrial Chemicals, Inc.; "Antifreezes and Deicing Fluids" in ECT, 2nd ed., Vol. 2, pp. 540-561, by R. W. Kallgren, The Dow Chemical Compa- ny 1. Frank Howard and co-workers, Automotive Antifreezes, National Bureau of Standards Circular 576, U.S. Department of Commerce, U.S. Government Printing Office, Washington, D.C., July 25, 1956. 2 Maintenance of Automotive Engine Cooling Systems, Society of Automotive Engineers (SAE) Booklet TR-40, Warrendale, Pa. 3. Summary of Antifreeze Sales for 1959 and 1960, Chemical Specialties Manufacturers Association, Bulletin No. 173-61, May 16,1961. 4. G. A. Paul, The Effect of Selected Coolants on Metal Temperatures in a Rotary Engine:, Paper 741091, SAE Automotive Engineering Meeting, Toronto, Canada, October 21-25, 1974. 5. G. 0. Curme, Sr., and F. Johnston, Glycols, Reinhold Publishing Corp., New York, 1952, p. 170. 6. Dow Propylene Glycol, USP, bulletin, The Dow Chemical Co., Midland, Mich., 1974. 7. Properties and Uses of Glycol, bulletin, The Dow Chemical Co., Midland, Mich., 1974. 8. Glycols, bulletin, Union Carbide Chemicals Co., Division of Union Carbide Corp., New York, 1958. 9. R. C. Weast and co-eds., Handbook of Chemistry and Physics, 56th ed., The Chemical Rubber Co., Cleveland, Ohio, 1967-1968. 10. J. A. Dean, ed., Lange a Handbook of Chemistry, 11th ed., McGraw-Hill Book Co., Inc., New York, 1961. 11. Physical Properties, Synthetic Organic Chemicals, bulletin, Union Carbide Chemicals Co., New York, 1961. 12. Physical Properties of Glycerine and its Solutions, bulletin, Glycerine Producers Association, New York. 13. DOWTHERM 209 Coolant, bulletin, The Dow Chemical Co., Midland, Mich., 1971. 14. AMBITROL Engine Coolants, The Dow Chemical Co., Midland, Mich., 1976. 15. Annual Book of ASTM Slandards, Part 30, American Society for Testing and Materials, Philadelphia, Pa. 16. E. Beynon and co-workers, Material Research and Standards, American Society for Testing and Materials, Philadelphia, Pa., June 1970, p. 33. 17. H. C. Duus, E. H. Kellner, and H. M. Cadot, lnd. Eng. Chem. 30,143 (1938). 18. J. E. Miller and T. Alfrey, Jr., The Effect of Ethylene Glycol and Methoxypropanol Based Coolants on Elastomers, Paper 680496, Mid-year Meeting, Detroit, Mich., May 20-24, 1968. 19. D. Caplan and M. Cohen, Corrosion (Houston) 9,284 (1953). J

Ki2KvoMmeR Vol. 11 GLYCOLS (ETHYLENE AND PROPYLENE) 951 Table 11. Toxicological Properties of Triethylene Glycol Derivatives' )erivative Single oral LDu, ratsb, g/kg Single skin penetration LDra, rabbits', mL/kg Single inhalationd concentrated vapors, rats Primary skin irritation°, rabbits Eye injury, rabbits Afunoethers methyl 11.86 7.1 8 h killed 0 of 6 trace none ethyl 10.6 8 none trace n-butyl 6.74 3.54 8 h killed 0 of 6 trace moderate Uiethers dimethyl 2.5-,5 none none Ilrr.ters diacetate 25.28 16 8 h killed 0 of 6 none trace ° Refs. 19, 21-22. h The term LD,,,o refers to that quantity of chemical that kills 50% of dosed animals within 14 d. Single skin penetration refers to a 24-h covered skin contact with the liquid chemical. d Single inhalation refers to the continuous breathing of certain concentrations of chemicals for the stated period. ~ Primary irritation refers to the skin response 24 h following application of 0.01 mL amounts to uncovered skin. 1 Eye injury refers to surface damage produced by the liquid chemical. lower hygroscopicity (1). Physical properties are listed in Table 1 and toxicological properties in Table 2. Tetraethylene glycol is a coproduct of ethylene glycol produced by ethylene oxide hydrolysis. Like triethylene glycol, tetraethylene glycol is also produced commercially by the direct reaction of ethylene oxide with the lower glycols. The price for tankcar quantities of tetraethylene glycol was $1.01/kg in early 1979. Tetraethylene glycol is used to separate aromatic from nonaromatic hydrocarbons by selective extraction. The critical solution temperature of a binary system consisting of a given alkyl-substituted aromatic hydrocarbon and tetraethylene glycol is lower than the critical solution temperatures of the same hydrocarbon with the lower polyglycols. Therefore, at a given temperature, tetraethylene glycol tends to extract the higher molecular weight alkylbenzenes more efficiently. Other uses are similar to those of triethylene glycol. Propylene Glycol 1,2-Propylene glycol is a clear, viscous, colorless liquid that is practically odorless and has a slight characteristic taste. Although more volatile than ethylene glycol, propylene glycol is about three times as viscous at room temperature. It has a very low order of toxicity and is highly hygroscopic. Physical properties of high-purity material are listed in Table 12. Propylene glycol from propylene oxide was discovered in 1859 by Wurtz (30). It was of little commercial importance, however, unti11931 when it was first produced by the hydrolysis of propylene oxide (qv). Today the hydrolysis is carried out under pressure and at high temperature without catalyst (eq. 19): CH, CH;, I up_ t 'o I CH.-CH + H.,O ' HOCHCH1OH + dipropylene glycol '0" 9-00 ~ propylene + higher adducts propylene glycol oxide CID ~ ~ N

/<r RK -OTNI+'IFK 952 GLYCOLS (ETHYLENE AND PROPYLENE) Table 12. Physicat Constants of Propylene Glycol• Property Value mp, °C -60b bp at 101.3 kPa°, °C 187.3 density at 20°C, g/cm3 1.0362 surface tension at 20°C, mN/m (= dyn/cm) 35.6 refractive index, ni? 1.4326 vapor pressure at 20°C, kPa° <1.3 specific heat, J/(g-OC)d as liquid, 20°C 2.481 as ideal gas, 25°C 1.611 heat of vaporization at 101.3 kPac, kJ/mold 52.296 heat of combustion at 25°C, kJ/mold 1824.0 critical constants pressure,kPa° 6100.27 temperature, °C 352 volume, L/mol 0.237 compression factor, Z, 0.278 viscosity, mPa-s (= cP) at 0°C 255.4 at 20°C 60.5 at 40°C 19.45 ° Ref. 29. b Sets to glass. I To convert kPa to mm Hg, multiply by 7.5. d To convert J to cal, divide by 4.184. The proportion of products is controlled by the mole ratio of water to propylene oxide (see below for isomer distribution in dipropylene glycol). Higher hydrolysis ratios increase the yield of propylene glycol but also the costs of purification. A ratio of 15 provides a product mix of 85% propylene glycol, 13% dipropylene glycol, and 1.5% higher adducts. Although propylene glycol has a secondary hydroxyl group, its chemistry parallels Table 13. United States Producers of Propylene Glycols Annual capacity, thousand metric tons Producer Location Propylene glycol° Dipropylene glycolb S.A Dow Chemical U Freeport Tex 113 4 11 8 M . . , . Plaquemine, La. . 68 . 5 m ~ Olin Corporation Brandenburg, Ky. 20.4 1.8 ~ Oxirane Corporation Bayport, Tex. 113.4 8.2 ~ Jefferson Chemical Company, Inc.° Port Neches, Tex. 18.1 3.2 N Union Carbide Corporation Institute and South Charleston, 45.4 3.6 ~ W. Va. Total 378.7 33.6 ° Ref. 14. b Ref. 15. 1 A wholly owned subsidiary of Texaco, Inc.

J<iR~ - 6TNmEP__ = vlene.nxide : lysi~ 'ius " ratio of I :i A >; i, and 1.;i~(' ry parallels Icin•. ric tons Uipropvlen<• Rlycol that of ethylene glycol. Propylene glycol is produced in the United States by five companies having a combined annual nameplate capacity of about 388 X 103 t (see Table 13). Uses. Propylene glycol has a variety of applications (see Table 14). In the food industry it is used as a solvent, humectant, and preservative, in the manufacture of products that come in contact with food such as plasticizers for food wraps, as a solvent for food processing, and as lubricant for food machinery. It is a softening agent, spreader, emollient, intermediate, drug vehicle, and preservative in the preparation of cosmetics and pharmaceuticals. Aqueous solutions are effective antifreeze mixtures (see Fig. 1) and are preferred in refrigeration (qv) units in breweries, dairies and packing houses, where a coolant or heat-transfer solution of low toxicity is important (see Antifreezes). These aqueous solutions are inhibited to prevent rust and corrosion. Derivatives. The derivatives of propylene glycol are prepared by methods anal- ogous to those for ethylene glycol derivatives. The base-catalyzed reaction of propylene oxide with alcohols gives predominantly primary monoalkyl ether, CH3CHOHCH2OR, and small amounts of secondary ether, CH3CHORCH2OH. Acid catalysis increases the ratio of secondary to primary ethers. Monoalkylethers can also be prepared without catalyst under the proper conditions of temperature and pressure. The monoalkyl ethers of propylene glycol are excellent solvents for a wide variety of organic materials. The lower alkyl ethers are completely miscible with water at room temperature and are soluble in some hydrocarbons. Properties for a number of these materials are listed in Table 15. The ethers and esters of propylene glycol are prepared from the glycol by con- ventional methods. Propylene glycol yields isomeric mixtures of esters because it contains both primary and secondary hydroxyl groups. Monoesterification occurs usually at the primary hydroxyl group. Fatty acid esters, such as the dioleate and the monohydroxystearate, are used in ointments, drug creams, cosmetics (qv), and sur- factants (qv). Dipropylene Glycol Dipropylene glycol is a coproduct of propylene glycol in the hydrolysis of pro- pylene oxide (eq. 19); the approximate isomer distribution is: HOCH_,CHOCHCH,OH CH,CHCH2oCHZCHCH, CH3CHCHzOCHCHzOH CH, CH, OH OH CH CH, 4% [108-61-2] 43% [110-98-5] 53% [106-62-7] Vol. 11 GLYCOLS (ETHYLENE AND PROPYLENE) 953 Table 14. Propylene Glycol Uses' Use Percent polyester resins 45 pet food 12 tobacco humectant 7 cellophane 7 food and pharmaceuticals 11 miscellaneous 6 exports 12 Total 100 ° Ref. 14.

g- ie ~-CrrNlw Table 1 (conrirwed) Solvent ethylene glycol monoethyl ether acetate ethylene glycol dimethyl ether ethylene glycol monobutyl ether diethylene glycol monoethyl ether ethylene glycol monophenyl ether ethylene glycol monobutyl ether acetate diethylene glycol monoethyl ether acetate diethylene glycol monobutyl ether propylene glycol monophenyl ether diethylene glycol mono-sec-butyl ether acetate Ketones acetone. methyl ethyl ketone (MEK) mesityl oxide cyclohexanone methyl n-butyl ketone (MBK) methyl isobutyl ketone diacetone alcohol methyl amyl ketone methyl isoamyl ketone diisobutyl ketone isophorone Others ethylene glycol propylene glycol diethylene glycol acetonitrile vdL . 2/ CAS Common name Empirical KB Solubility parameter b, Registry No. (trade name) formula value°•D (J/m3)1M X 10-3 ° [111-15-9) 2-ethoxyethyl acetate Csl-I120;a 4.2 (Cellosolve acetate) 1110-71-41 (dimethyl Cellosolve) C6H1402 [111-76-2] 2-butoxyethanol C6Hi402 4.6 (butyl Cellosolve [111-90-0] (Carbitol) C6H1403 4.98 [122-99-6) (butyl Carbitol) [112-07-2] (butyl Cellosolve) CaHio02 C8Hi60:1 4.1 acetate) [112-15-2] (Carbitol acetate) C8H1604 4.1 [112-34-51 (butyl ethyl Cello- C8H1s0x 4.6 solve) [770-35-4] (Polysolve PM) C9H1202 4.93 [124-17-4) (butyl Carbitol Cio!-12o0a 4.1 acetate) [67-64-1 ] 2-propanone, di- GiH60 4.8 methyl ketone [78-93-3] 2-butanone C4H80 4.5 [141-79-7] 4-methyl-3-penten- CsH,o0 4.4 2-one [108-94-1) cyclohexyl ketone C6H1o0 4.8 [591-78-67) 2-hexanone CsH120 4.0 [108-10-1 ] C6H 120 4.1 (123-42-2] diacetone, 4- C6Hi202 4.5 hydroxy- 4-methyl-2-penta- none [110-43-0) 2-heptanone 7H40 .1 [110-12-3] C7H140 4.1 1106-83-8] CsHsO 3.8 [78-59-1) 3,5,5-trimethyl-2-cy- CsHl40 4.4 clohexen-l-one [107-21-1) C2H602 7.12 (57-55-6] CaH802 6.15 (111-46-6) C4Hio03 5.90 [75-05-8] methyl cyanide C2H3N 5.80 384 Wat (at : w) other In wa 22.9 m m 2.2 1.1 m w 6.5 m 2420 1.7 m 0.4 6.5 0.05 1.2

XE2,c- - OTNm e ~ L'OC„ 2 f Water solubility (at 25°C, except where noted otherwise), wt%d•" In water Water in 22.9 m m 6.5 2.2 1.1 1.6 m m 6.5 3.7 m 2420 1020 2.3_,,, 8.020 1.4 1.7 1.9 m 0.4 1.5 6.5 1.2 0.05 0.8 1.2 4.3 ~ m m zeo- Boiling range at 101.3 kPa Vapor pressureg at 25°C except where noted Specific gravity' (at 20°C except where Refractive indexi (at 20°C except where Freezing trope, wt%/°C (= 1 atm), °C/ otherwise), kPah noted otherwise) noted otherwise) pointk, °C 44.4/97.5 156 0.145 0.9730 1.4023~~~, -62 83 6.4p 0.8692 -60 20.8/98.8 170 0.11 0.90075 1.4198 none 202 0.017 0.9885 1.4273 215 1.03 192 0.9424 -64 none 217 0.013 1.0096 1.4213 -25 231 0.003 0.9553 -68 247 0.0013 0.981 -32 none 56 24.3 0.78998 1.35868 -95 88.7/73 79 12 0.8049 1.3788 -87 130 1.3 0.8539 -59 45/96 156 0.64 0.9509915 1.45097 -32 127 1.339 0.8300 -57 75.7/87.9 116 2.7 0.8008 1.3957 -84 15.7/99.5 168 0.23 0.9387 1.4235 -44 150 138 0.817 1.4110 144 0.8132 -74 166 0.81 1.4230 -47 215-220 0.922 none 197 0.016 1.1135 1.4318 -13 none 187 0.017 1.0362 1.4329 -60 none 244 <0.0013 1.1164 1.4475 -6.5 84.2/76.7 82 11.8 0.7822 1.34411 -44