124 Chlorinated Hydrocarbons ers, and road or rail tankers. Steel is a suitable duction of 3,4-dichlorobenzyl chlo- material for construction of containers. ride, 3,4-dichlorobenzaldehyde, 3,4-di- For information on storage and handling, see chlorobenzotrichloride, and 3,4-dichloroben- Section 8.1.5. zoic acid, from which disinfectants, crop pro- Freight classifications are given in Table 49. tection products, and dyes are produced. 2,3,6-Trichlorotoluene. 2,3,6-Trichloro- is used on a small scale, together 8.2.6. Uses with 2,4,5-trichlorotoluene, to produce 2,3,6- trichlorobenzoic acid, a herbicide precursor. Isomeric mixtures of the monochlorotoluenes Producers of chlorinated are: Bayer are hydrolyzed to on a considerable scale. AG (FRG); Enichem (Italy); Hodogaya Chemi- Chlorotoluenes are also used as in reac- cals Co. Ltd. (Japan); Hoechst AG (FRG); Ihara tions and to dissolve special products, e.g., dyes. Chemical Ind., Ltd. (Japan); Occidental Chem- 2-Chlorotoluene. 2-Chlorotoluene is a start- ical Co., Ltd. (USA). ing material in the production of 2-chloro- , 2-chlorobenzaldehyde, 2- chlorobenzotrichloride, 2-chlorobenzoyl chlo- 8.3. Chlorinated Biphenyls ride and 2-chlorobenzoic acid, which are NewsomeNote: PCBs precursors for dyes, pharmaceuticals, opti- Industrial use of the polychlorinated biphenyls cal brighteners, fungicides, and products of first began in 1929 in the USA [880, 881]. The other types. 2-Chlorotoluene is also used in outstanding properties of these compounds, such the production of dichlorotoluenes (chlorina- as their high chemical and thermal stability, high tion), 3-chlorotoluene (isomerization), and o- dielectric constant, and the fact that they form chlorobenzonitrile (ammonoxidation). only incombustible gases in an electric arc, made 4-Chlorotoluene. 4-Chlorotoluene is used them appear ideally suited for use as insulating mainly to produce p-chlorobenzotrichloride, and cooling fluids for transformers and as di- from which is obtained p-chlorobenzotrifluoride, electric impregnants for capacitors. an important precursor of herbicides (e.g., In subsequent years many other applications trifluralin:α,α,α,-trifluoro-2,6-dinitro-N,N- were found as well (see Section 8.3.5), particu- dipropyl-p-toluidine). Other side-chain-chlo- larly for isomeric mixtures containing two to six rinated products or their derivatives are 4- atoms of chlorine per mole of biphenyl. chlorobenzyl chloride (for pharmaceuticals, In the mid-1960s, improved analytical meth- rice herbicides, and pyrethrin insecticides), 4- ods revealed that polychlorinated biphenyls chlorobenzaldehyde (for dyes and pharmaceuti- were accumulating in nature as a consequence of cals), 4-chlorobenzoyl chloride (for pharmaceu- their extremely low rates of biological degrada- ticals and peroxides), and 4-chlorobenzoic acid tion (rates which decrease as the chlorine content (for dyes). 4-Chlorotoluene is also a starting rises). The compounds were detected in fresh material in the synthesis of 2,4- and 3,4-di- water in all parts of the world, but also in many chlorotoluene and of 4-chlorobenzonitrile. animals (e.g., birds, fish, and plankton). In the late 1970s, it was further discovered that at tem- 2,4-Dichlorotoluene. 2,4-Dichlorotoluene peratures of 500 to 800 ◦C in the presence of is used via its side-chain-chlorinated intermedi- oxygen, polychlorinated biphenyls can give rise ates to produce fungicides, dyes, pharmaceuti- to polychlorinated dibenzofurans and dibenzo- cals, preservatives, and peroxides (curing agents dioxins, including (although to a much smaller for silicones and polyesters). extent) the particularly toxic compound 2,3,7,8- 2,6-Dichlorotoluene. 2,6-Dichlorotoluene tetrachlorodibenzodioxin [882 – 887]. is used to produce 2,6-dichlorobenzaldehyde, a In the meantime, all but a few of the well- dye precursor, and 2,6-dichlorobenzonitrile, a known producers (see Section 8.3.5) discon- herbicide. tinued the production of chlorinated biphenyls. 3,4-Dichlorotoluene. 3,4-Dichlorotoluene Moreover, in many countries the production, is used in small amounts in the pro- sale, and use of polychlorinated biphenyls have Chlorinated Hydrocarbons 125

Table 49. Freight classification

GGVE/GGVS and IMDG Code and IATA-DGR US-DOT RID/ADR class number class UN No. pack. group

2- and 4-Chlorotoluene3 3 3.3 2238 III UN 1993 Flammable liquid 2,3-Dichlorotoluene 3 4 not restricted 2,4-Dichlorotoluene 3 4 not restricted 2,6-Dichlorotoluene 3 4 not restricted 3,4-Dichlorotoluene 3 4 not restricted

been restricted or entirely prohibited by legisla- hexachlorobiphenyl [26601-64-9]. Such mix- tion. tures are liquid to viscous (pour points increase For many years, o-, m- and p-terphenyl mix- with chlorine content from − 22 to + 18 ◦C), and tures were chlorinated and then used as plasticiz- they are fire-resistant. Further chlorination gives ers, flame retardants, and fillers in thermoplastic soft to brittle thermoplastic waxes. pattern and holding waxes. This application like- Chlorinated biphenyls are soluble in many wise has been substantially discontinued [888], organic solvents, particularly when heated, but particularly in view of the persistent nature of are soluble in water only in the ppm range. Al- the compounds in question and their accumula- though they are chemically very stable, includ- tion in the environment. Possible toxicological ing to oxygen of the air, they can be hydrolyzed hazards are either unknown or have not been ad- to oxybiphenyls under extreme conditions, e.g., equately investigated (Table 50). with sodium hydroxide solution at 300 – 400 ◦C and under high pressure. Toxic polychlorodiben- Table 50. MAK and TLV values of chlorinated biphenyls zofurans may be formed under these conditions. The fact that the compounds may eliminate MAK TLV hydrogen chloride to a small extent at a high tem- NewsomeNote: These are (FRG) (USA) 3 3 maximum daily exposure levels. mg/m mg/m perature explains why hydrogen chloride accep- tors are often added to transformer fluids based Chlorinated biphenyls (42 % Cl) 1 III B 1 Chlorinated biphenyls (54 % Cl) 0.5 III B 0.5 on polychlorinated biphenyls. The excellent electrical property data of polychlorinated biphenyls, such as high dielec- In view of the above, this article is devoted tric constant, low power factor, high resistivity, primarily to a review of recent patents covering favorable dielectric loss factor, and high dielec- methods for the disposal of polychlorinated bi- tric strength, have already been mentioned. phenyls. For information regarding the produc- tion of these compounds and their specific physi- cal and chemical properties, attention is directed 8.3.2. Disposal to earlier surveys [882, 889, 890]. Many products containing chlorinated biphenyls are still in use throughout the world, particu- 8.3.1. Physical and Chemical Properties larly in transformers, rectifiers, and capacitors There are 209 possible chlorinated biphenyls. with long service lives. Industry and national The mono- and dichlorobiphenyls [27323-18- governments are now faced with the need to 8], [25512-42-9] are colorless crystalline com- dispose of these products without causing addi- pounds (the melting points of the pure isomers tional pollution of the environment. Appropriate lie between 18 and 149 ◦C). When burned in air, official regulations exist in many countries [888, they give rise to soot and hydrogen chloride. 891 – 902]. The most important products are mixtures Attention is drawn in the following survey to whose principal components are trichlorobiphe- patents concerned with the removal of polychlo- nyl [25323-68-6], tetrachlorobiphenyl [26914- rinated biphenyls from electrical devices and 33-0], pentachlorobiphenyl [25429-29-2], or 126 Chlorinated Hydrocarbons with the disposal of these compounds. It is im- 8.3.3. Analysis possible to say which of the processes have ac- tually reached maturity and which are already The analytical methods most frequently used being used. for detecting chlorinated biphenyls are capil- According to the present state of knowl- lary column gas chromatography coupled with edge, polychlorinated biphenyls can be de- mass spectrometry in the MID (Multiple Ion De- stroyed harmlessly by combustion at tempera- tection) mode and capillary column gas chro- tures above 1000 ◦C and a residence time of 2 s, matography with ECD (Electron Capture Detec- e.g., in a rotary burner equipped with a scrubbing tor). These methods are suitable for solution of tower for hydrogen chloride [888, 902 – 904]. even the most difficult problems. Clean-up steps Regulations in the Federal Republic of Germany are necessary when complex matrices are con- specify a temperature of 1200 ◦C, a residence cerned, such as preliminary separation by col- time of 0.2 s, and a residual oxygen content in umn chromatography. the combustion gas of 6 % [897]. HPLC (High Pressure Liquid Chromatogra- Removal of polychlorinated biphenyls from phy) and infrared spectroscopy are applicable to silicone- and hydrocarbon-based transformer a limited extent. fluids and heat transfer media is accomplished Summary polychlorinated biphenyl determi- through the formation of a separable fraction nations are also possible, though not usual. rich in polychlorinated biphenyls [905], treat- These require either exhaustive chlorination and ment with polyalkylene glycol and alkali metal measurement of the decachlorobiphenyl content hydroxide [906, 907], treatment with sodium or else dechlorination and subsequent measure- naphthalenide [908], or heating with a sodium ment of the biphenyl content. dispersion to 75 ◦C [909]. For literature references on the subject of Polychlorinated biphenyls are removed from analysis, see [902, 921 – 927]. impregnated electrical parts by irradiation with microwaves, which causes gasification of the compounds [910], or by dry distillation at 500 – 8.3.4. Storage and Transportation 1000 ◦C followed by addition of oxygen [911]. Destruction of polychlorinated biphenyls has At a normal temperature the commercially used been reported to be possible by the following polychlorinated biphenyls are liquid to viscous methods: treatment with sodium naphthalenide mixtures with a comparatively low vapor pres- in the presence of metallic sodium [912]; treat- sure (trichlorobiphenyl 6.5×10−5 kPaat20◦C). ment at 145 ◦C with a dehalogenating reagent Steel and aluminum are suitable as container ma- prepared from an alkali metal, polyethylene gly- terials. The storage and shipping of these com- col, and oxygen [913];reaction with sulfur in the pounds are subject to a variety of national reg- vapor phase [914];adsorption on paramagnetic ulations. Since these compounds accumulate in or ferromagnetic material and subsequent irra- the environment they must be handled so that diation with microwaves in the presence of oxy- release cannot occur. gen [915]; and irradiation with light in aqueous Exposure of polychlorinated biphenyls to fire solution in the presence of a catalyst [916]. may result in the formation of toxic chlorinated Thermal decomposition of polychlorinated dibenzofurans and dibenzodioxins [882 – 887] biphenyls occurs by pyrolysis under oxidative and in the evolution of hydrogen chloride. conditions (oxygen-enriched air) on molten al- Classification of polychlorinated biphenyls kali carbonates at 900 – 980 ◦C [917]; by use are: of a plasma burner at 3000 – 4000 ◦C [918]; by GGVE/GGVS and RID/ADR: Class 6.1, Num- dissolution in kerosene, followed by combustion ber 23 in air and introduction of the combustion gases IMDG-Code and IATA-DGR: Class 9, UN into a special decomposition furnace [919]; or Number 2315, Packaging group II by evaporation with hydrogen as a carrier gas, US D.O.T.: ORM.E, UN Number 2315 followed by combustion in oxygen [920]. Chlorinated Hydrocarbons 127

8.3.5. Uses 8.4. Chlorinated Naphthalenes

Use of these compounds has fallen drastically The first industrial applications of chlorinated [928] as a result of the extensive discontinua- naphthalenes took place at the beginning of tion of their production, voluntary renunciation the 20th century [929]. The compounds were of their application, and national restrictions. No used most extensively in the 1930s to 1950s, details were available concerning products in especially in cable and capacitor production, which polychlorinated biphenyls are still used, prompted by their dielectric, water-repellent, nor concerning the scale of such use. The follow- and flame-retardant properties. ing list of important fields of application should More recently, most producers of polychlo- be regarded as retrospective: rinated naphthalenes have stopped their pro- duction, and output has been reduced drasti- Cooling and insulating fluids for transformers cally in all parts of the world. The reasons Dielectric impregnating agents for capacitors for this follow. First, connections have been Flame-retardant additives for resins and plas- established between highly chlorinated naph- tics used in the electrical industry thalenes, especially pentachloronaphthalene and Alkali- and acid-resistant plasticizers for lac- hexachloronaphthalene, and illness. Moreover, quers, plastics, adhesives, fillers and sealing because of their high chemical and thermal sta- compositions bility, highly chlorinated naphthalenes are able Formulations for paints and printing inks to accumulate in the environment. Finally, new Water-repellent additives for surface coatings materials (polyesters and polycarbonate) have Dye carriers for pressure-sensitive copying been introduced as substitutes for chlorinated paper naphthalenes in the capacitor and cable indus- Additives for thermally-stable lubricants and tries. gear oils Monochloronaphthalenes, by contrast, are Incombustible hydraulic fluids (particularly not considered to be problematic with regard to suitable for use in locations to which access their effects on health and accumulation in the is difficult, e.g., in mines) environment [930]. Heat transfer fluids of high heat stability Official regulations relating to chlorinated Inert sealing fluids for vacuum pumps naphthalenes differ considerably from country Dust control agents for road construction to country. In Japan, for example, polychlori- Mono- and dichlorobiphenyls have been used nated naphthalenes are prohibited entirely. In the on a small scale as precursors for the correspond- USA they may still be used without restriction, ing oxybiphenyls. but changes in their production, importation, or Some registered trademarks are listed in Ta- use must be reported to the U.S. Environmental ble 51. Most of the listed producers have discon- Protection Agency (EPA) [931], so that the ef- tinued production. fects of these changes on the environment may be monitored.

Table 51. Trade names of chlorinated biphenyls 8.4.1. Physical Properties Apirolio Caffaro, Italy Aroclor Monsanto, USA, UK Naphthalene has 75chlorinated derivatives. To Clophen Bayer AG, FRG date, however, only a few have been synthesized Delor Chemco, Czechoslovakia Fenclor Caffaro, Italy and isolated in pure form. Only isomeric mix- Inerteen Westinghouse, USA tures characterized according to their chlorine Kanechlor Kanegafuchi Chem. Co., Japan content are as a general rule commercially avail- Pyralene Prodelec, France able. This situation arises because of the fact that Pyranol Monsanto, UK Pyroclor Monsanto, USA the most important characteristics of the com- Sovtol USSR pounds are a function solely of their degree of chlorination, as a result of which there is lit- tle demand for the pure compounds. Moreover, precisely because the physical properties of the Chlorinated Hydrocarbons 155 available on chronic effects or effects on repro- The PCBs failed to show positive response duction caused by chlorinated toluenes. in validated mutagenicity test systems. The in- In humans, no cases of poisoning or skin irri- terference of polychlorinated biphenyls with re- tation caused by chlorinated toluenes have been production could be demonstrated in numerous reported [1064]. studies with mammals. The compounds pass Regulations. o-Chlorotoluene TLV 50 ppm through the placental barrier and exhibit embry- otoxic effects [1069]. Absorption, Metabolism, and Excretion. 10.2.3. Polychlorinated Biphenyls Polychlorinated biphenyls are readily absorbed from the gastrointestinal tract after ingestion Acute Toxicity. The acute toxicity of mix- or from the lung after inhalation. The rates tures of polychlorinated biphenyls (PCB) seems of metabolism and excretion decrease and the to depend on the chlorine content. Table 64 storage in body fat increases with increasing demonstrates the influence of the chlorine con- chlorine content. The compounds are generally tent in mixed isomers of PCBs, in addition to metabolized by selective hydroxylation. In pri- their relatively low acute oral toxicity. mates, most of the metabolites are excreted as NewsomeNote: LD is the median Lethal Dose to kill 50 conjugates in the urine, whereas excretion of free 50% of a population. Lower numbers are more toxic. Table 64. Acute oral toxicity of PCBs [1090] metabolites in the feces is the major route in ro- dents [1093]. Chlorine content, wt % LD50 (rat, oral), g/kg Other Effects. Immunosuppressive action of polychlorinated biphenyls in mammals could be 21 3.98 evidenced by a decrease in infectious resistance 32 4.47 42 8.65 with atrophy of the spleen, cortical thymus atro- 48 11.0 phy, and dose-dependent decreased in the pro- 62 11.3 duction of specific antibodies [1063, 1069]. In 68 10.9 hens, growth retardation, high mortality, and subcutaneous edema could be observed. These The administration of acute or subacute doses findings were accompanied by focal necrosis results in liver enlargement, mainly due to en- of the liver, hydroperitoneum, and epicardial as zyme induction; when the doses were increased, well as lung edema (chicken edema disease) fatty degeneration and central atrophy of the [1063, 1069]. liver occurred. In addition, hyperplasia and Experience in Humans. Accidental acute in- hemosiderosis of the spleen were also observed toxications with PCBs are not reported [1069]. [1091, 1092]. Polychlorinated biphenyls are not With workers handling these compounds, acne- likely to possess a substantial local irritating po- form dermatitis was observed, in addition to liver tential. Nevertheless, they seem to be readily ab- damage with necrosis [1063, 1069]. sorbed through the skin, exerting such systemic In 1968, a subacute intoxication of more than effects as liver damage. 1000 people in Japan by contaminated rice oil Chronic Effects. After oral application, se- was reported (Yusho disease). Initial symptoms vere liver damage (hypertrophy, fatty degener- were, for instance, swelling of the eye lids, fa- ation, and centrolobular necrosis) is most likely tigue, and gastrointestinal disturbances. Later to be observed. The skin is also often affected on, discoloration of the skin and mucous mem- (hyperplasia, hyperkeratosis, and cystic dilata- branes, headache, signs of sensory nerve injury, tion) [1069]. Polychlorinated biphenyls can in- diarrhea, and jaundice were found. Cases of in- terfere with heme metabolism as shown by an fluence on human fetuses have been attributed increased porphyrin content of the liver in rats to this high PCB exposure [1063, 1069]. [1069]. Hepatocellular tumors are produced in Polychlorinated biphenyls accumulate in fat rats and mice after long-term oral application of and adipose tissue. They have been demon- PCBs [1066], vol. 20. However, the tumor for- strated in human milk. Because the PCB level mation is regarded as a response to tissue dam- was found to be higher in infant blood but lower age rather than triggered by a genotoxic mecha- in umbilical blood in comparison to maternal nism. 156 Chlorinated Hydrocarbons blood, the transfer of PCBs via the milk is proba- 1-Chloronaphthalene and 1,2,3,4-tetra- bly much more important than placental transfer chloronaphthalene, when tested for point mu- [1063, 1094]. tations in the Salmonella assay (Ames test), Regulations. The following exposure limits exhibited no positive results [1097, 1098]. No have been established: data are available on the effects of chlorinated NewsomeNote: These are naphthalenes on reproduction. maximum daily exposure levels. Metabolism. Chlorinated naphthalenes are Chlorine content 42 %: MAK 0.1 ppm Chlorine content 54 %: MAK 0.05 ppm readily absorbed. Metabolism occurs by con- jugation or via hydroxylation to the respective naphthols or dihydrodiols. The metabolites are Polychlorinated biphenyls are considered excreted with the urine or the feces [1063, 1096]. as possible teratogens [1095] and carcinogens Effects in Humans. The main health problem [1069]. arising from use and handling of chlorinated naphthalenes is chloracne, which usually occurs from long-term contact with the compounds or 10.2.4. Chlorinated Naphthalenes exposure to hot vapors. The penta- and hex- achloro derivatives are suggested to have the Monochlorinated naphthalenes are of low to greatest potential to generate acne [1063]. moderate acute toxicity, as shown by their oral In accidental intoxications, liver damage oc- LD50 (Table 65). Subacute to subchronic uptake curred independently from chloracne. After loss of mixtures of higher chlorinated naphthalenes of appetite, nausea, and edema of the face and (predominantly penta- and hexachloronaphtha- hands, abdominal pain and vomiting followed; lene) resulted in liver injury [1063]. In gen- later on jaundice developed. Autopsy in cases of eral, the toxicity of chlorinated naphthalenes in- fatal intoxication revealed yellow atrophy of the creases with the degree of chlorination [1064]. liver [1096]. Chlorinated naphthalenes irritate the rabbit Regulations. The following exposure limits skin [1063]. Ingestion of lubricants containing have been established: chloronaphthalenes resulted in injury to farm animals (X disease). Marked hyperkeratosis of 3 Trichloronaphthalene: MAK 5mg/m , 3 the skin, degenerations of the cells in pan- TLV 5mg/m 3 creas, liver, and gall bladder, and damage of Tetrachloronaphthalene: TLV 2 mg/m 3 Hexachloronaphthalene (skin): TLV 0.2 mg/m the renal cortex could be observed. Cattle 3 Pentachloronaphthalene: TLV 0.5mg/m 3 poisoned with highly chlorinated naphthalenes Octachloronaphthalene (skin): TLV 0.1 mg/m show a rapid decline in vitamin A plasma lev- els [1063]. Octachloronaphthalene fed to rats also greatly enhances the loss of vitamin A from the liver [1096]. Mixtures of penta- and 10.2.5. Benzyl Chloride hexachloronaphthalenes can produce the so- called chicken edema disease, characterized The acute oral toxicity (LD50) of benzyl chlo- by hydropericardium and ascites in chickens ride in rats is 1231 mg/kg and in mice 1624 [1096]. mg/kg [1083]. The subcutaneous LD50 (in rats) of benzyl chloride in oil solution is 1000 mg/kg [1099]. Exposure of rats and mice to benzyl Table 65. Oral LD50s of monochlorinated naphthalenes [1083] chloride concentrations of 100 –1000 mg/m3 for

Compound Species LD50 (oral), 2 h caused irritation of the mucous membranes mg/kg and conjunctivitis [1066], vol. 11. Benzyl chlo-

1-Chloronaphthalene rats 1540 ride is a strong skin-sensitizing agent for guinea mice 1019 pigs [1100]. Benzyl chloride acts weakly muta- 2-Chloronaphthalene rats 2078 genic in validated test systems [1101, 1102]. mice 886 Subcutaneous injection of weekly doses of 80 mg/kg for 1 year followed by a post-observation period resulted in local sarcomas with lung