1,2-dichloroethane

Environmental Fate and Behavior

1,2-Dichloroethane can enter the environment when it is made, packaged, shipped, or used. Most 1,2-dichloroethane is released to the air, although some is released to rivers or lakes. 1,2-Dichloroethane could also enter soil, water, or air in large amounts in an accidental spill (evaporates into the air very fast from soil and water). If released to air, a vapor pressure of 78.9 mm Hg at 25 °C indicates that 1,2-dichloroethane will exist solely as a vapor in the ambient atmosphere. Vapor-phase 1,2-dichloroethane will be degraded in the atmosphere by reaction with photochemically produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 63 days. Indirect evidence for photooxidation of 1,2-dichloroethane comes from the observation that monitoring levels are highest during the night and early morning. It may also be removed from air in rain or snow. Since it stays in the air for a while, the wind may carry it over large distances. In water, 1,2-dichloroethane breaks down very slowly and most of it will evaporate to the air. Only very small amounts are taken up by plants and fish. Exact longevity of 1,2-dichloroethane in water remains unknown. It is thought that it remains longer in lakes than in rivers.

In soil, it either evaporates into the air or travels down through soil and enters underground water. 1,2-Dichloroethane has been found in the United States drinking water at levels ranging from 0.05 to 64 ppb. An average amount of 175 ppb has been found in 12% of the surface water and groundwater samples taken at 2783 hazardous wastes sites. 1,2-Dichloroethane has also been found in the air near urban areas at levels of 0.10–1.50 ppb and near hazardous waste sites at levels of 0.01–0.003 ppb. Small amounts of 1,2-dichloroethane have also been found in foods. Small organisms living in soil and groundwater may transform it into other, less harmful compounds, although this happens slowly. Large amounts from an accident, hazardous waste site, or landfill may likely reach the underground and contaminate drinking water wells. Biodegradation occurs slowly in water and soil surfaces. It is not expected to undergo hydrolysis and photolysis. Humans may get exposed to very low levels of 1,2-dichloroethane through its use as a gasoline additive (leaded gasoline is no longer used in the United States).

7.19.2.3 1,2-Dichloroethane (Ethylene Dichloride)

1,2-Dichloroethane is one of the most abundant synthetic chemicals in the United States and is used mainly as an intermediate in the production of vinyl chloride. Human exposure to 1,2-dichloroethane occurs mostly via inhalation of vapors at industrial sites. However, drinking water may also be a source of human exposure (Morgan et al. 1990). 1,2-Dichloroethane intoxication in humans can produce acute renal failure that is associated with oliguria, albuminuria, and increased blood urea nitrogen concentrations. The renal lesion, characterized by accumulation of fat and degeneration of tubular epithelium, appears to be selectively localized to the proximal tubular epithelium (Yodaiken and Babcock 1973). Single and repeated inhalation exposure of rats, guinea pigs, and monkeys to 1,2-dichloroethane at concentrations of 400–2400 ppm resulted in fatty degeneration, cast formation, and proliferation of the tubular epithelium (Spencer et al. 1951; Yodaiken and Babcock 1973). However, when 1,2-dichloroethane was given in drinking water at 8000 ppm for 13 weeks to both sexes of F344/N rats, Sprague–Dawley rats, and Osborne–Mendel rats, only female F344/N rats exhibited renal lesions (Morgan et al. 1990). These results suggest that animals may be more susceptible to 1,2-dichloroethane-induced nephrotoxicity after inhalation exposure compared with exposure by drinking contaminated water. While the above results also suggest that female F344/N rats are unusually sensitive to 1,2-dichloroethane nephrotoxicity when administered orally, the biochemical basis for this sensitivity remains unclear. While in vitro studies with 1,2-dichloropropane, a nephrotoxic analogue of 1,2-dichloroethane, show that renal cortical slices from male Wistar rats are more sensitive to 1,2-dichloropropane-induced toxicity than females, possibly because of higher expression of CYP2E1 in the male rat kidney (Odinecs et al. 1995), the effect of gender on 1,2-dichloropropane in vivo nephrotoxicity has not been investigated.

CYP-mediated oxidation at one of the carbon atoms forms a highly unstable gem-chlorohydrin that spontaneously decomposes to yield the electrophilic metabolite, 2-chloroacetaldehyde. 2-Chloroacetaldehyde may react with GSH to yield 2-(S-glutathionyl) acetaldehyde, which can then be reduced by alcohol dehydrogenase to yield S-(2-hydroxyethyl)glutathione. 2-Chloroacetaldehyde can also be oxidized by aldehyde dehydrogenase to chloroacetic acid, a major urinary metabolite of 1,2-dichloroethane. The alternative metabolic pathway involves GSH conjugation by cytosolic glutathione S-transferases to yield S-(2-chloroethyl)glutathione, half-sulfur mustard, which may rearrange to an electrophilic episulfonium ion. This episulfonium ion can either be hydrolyzed to yield S-(2-hydroxyethyl)glutathione or react with GSH to yield S,S′-(1,2-ethanediyl)bisglutathione or ethylene. An in vitro study in rat hepatocytes suggests that glutathione S-transferase-catalyzed reactions are responsible for the majority of GSH depletion induced by 1,2-dichloroethane, 1,2-dibromoethane, and 1-bromo-2-chloroethane (Jean and Reed 1992). Because chloroacetaldehyde and S-(2-chloroethyl)glutathione, and its putative metabolite S-(2-chloroethyl) cysteine, have been shown to cause nephrotoxicity in vivo and cytotoxicity in vitro, and/or can act as alkylating agents (Elfarra et al. 1985; Erve et al. 1995; Guo et al. 1990; Kramer et al. 1987; Meyer et al. 1994; Sood and O’Brien 1994; Zamlauski-Tucker et al. 1994), the formation of these metabolites is implicated in 1,2-dichloroethane-induced nephrotoxicity.

1,2-Dichloroethane metabolism by glutathione S-transferases and CYP to yield nephrotoxic metabolites may occur in both liver and kidney. The relative roles of hepatic and renal metabolism by either pathway are likely to be species-, sex-, and age-dependent (Gonzalez and Gelboin 1994; Hinchman et al. 1991; Hu et al. 1993; Rozell et al. 1993; Singhal et al. 1992; Vos and Van Bladeren 1990). For S-(2-chloroethyl)glutathione and S-(2-chloroethyl) cysteine, renal transport mechanisms may play a major role in determining the target organ of toxicity caused by these S-conjugates. Thus, conjugates formed in the liver are likely to be translocated via the systemic circulation and/or the enterohepatic circulation to the kidney, where they can be actively transported and concentrated within the tubular epithelium (Dantzler et al. 1995; Elfarra et al. 1985; Guo et al. 1990; Kramer et al. 1987; Lash and Anders 1989; Monks and Lau 1987; Schaeffer and Stevens 1987; Silbernagl and Heuner 1990).

1.10 Isomers

The physical properties of these two functional group isomers, as exemplified by their boiling points, are very different. These substances also have different chemical properties because their functional groups differ.

Positional isomers are compounds that have the same functional groups in different positions on the carbon skeleton. For example, the isomeric alcohols 1-propanol and 2-propanol differ in the location of the hydroxyl group. The chemical properties of these two compounds are similar because they both contain the same type of functional group and have identical molecular weights.

6.3.2.3.5 By electrophilic aromatic substitution of thiophenes

2.7 Isomers

Compounds that have the same molecular formula whose atoms are linked in different ways are called isomers. As we examine the structure of organic compounds in detail, we will find that subtle structural differences profoundly affect the physical and chemical properties of isomers.

We can divide isomers into two broad classes. Substances that differ in their connectivity are constitutional isomers. Isomers that have the same connectivity but differ in the arrangement of the atoms in space are stereoisomers. We will consider stereoisomers in greater detail in Chapter 8 and thereafter.

Constitutional isomers can also have different functional groups. For example, both ethyl alcohol and dimethyl ether have the same molecular formula: C₂H₆O. Although the molecular formulas of the two compounds are identical, their functional groups differ (Figure 2.5). The atomic connectivity is C─C─O in ethyl alcohol and the oxygen atom is part of an alcohol. In contrast, the C─O─C connectivity in the isomer forms an ether.

4.2.2 Plantwide control problem

The quality of the intermediate DCE must fulfil strict purity specifications. Low impurity levels imply high energetic consumption, but higher impurity amounts are not desired for operation. The intermediate DCE is conditioned mainly in the distillation column S2. In the bottom product the concentration of the two "bad impurities" I₁ and I₂ must not exceed an upper limit, of 100 and 600 ppm, respectively, while the concentration of the good impurity I₃ must be kept around optimal value of 2000 ppm.

Because the key impurities are implied in all-three reaction systems through recycles that cross in the separation system, their inventory is a plantwide control problem. This is completed by technological and environmental constraints, as mentioned.

The advanced removal of I₁ and I₂ must find a compromise with an optimal concentration of I₃ in the bottom product of column S2. It is worth to mention that these contradictory requirements cannot be fulfilled by any stand-alone design of S2. Thus, the effective control of impurities becomes possible only by exploiting the positive feedback effects of the recycle loops that are balanced by the negative feedback effects of chemical conversion and exit streams.

Hence, the plantwide control objective is the quality of DCE sent to the cracking section, for which three specifications regarding key impurities are required. These are the outputs of the plantwide control problem, available by direct concentration measurements, as by IR spectroscopy or on-line chromatography.

An analysis of the degrees of freedom indicates as first choice manipulated variables belonging to the column S2, used for quality control: D2 - distillate flow rate, SS2 - side stream flow rate, and Q2 - reboiler duty. We may also consider manipulated variables belonging to the column S4, adjacent and connected with S2 by a recycle, but dynamically much faster. Thus, supplementary inputs are: D4 - distillate flow rate, and Q4 - reboiler duty. Hence, the inputs are the variables D2, SS2, Q2, D4 and Q4.

A major disturbance of the material balance is simulated here by a step variation in the external feed (F_DCE). A second significant disturbance is X₁₃, the fraction of impurity I₃ introduced by the external DCE feed. The most probable range of frequencies for disturbance rejection is 0.1-1 rad/h for throughput, and 0.1-10 rad/h for impurities.

2.3 Catalytic measurements

4742. Dinitrogen tetraoxide (Nitrogen dioxide)

[10544-72-6]

HCS 1980, 675 (cylinder)

The equilibrium mixture of nitrogen dioxide and dinitrogen tetraoxide is completely associated at —9°C to the latter form which is marginally endothermic (ΔH°_f (g) +9.7 kJ/mol, 0.10 kJ/g). Above 140°C it is completely dissociated to nitrogen dioxide, which is moderately endothermic (ΔH°_f (g) +33.8 kJ/mol, 0.74 kJ/g).

Acetonitrile, Indium

MRH Acetonitrile 7.87/25

Addison, C. C. et al., Chem. & Ind., 1958, 1004

Shaking a slow-reacting mixture caused detonation, attributed to indium-catalysed oxidation of acetonitrile.

Alcohols

Daniels, F., Chem. Eng. News, 1955, 33, 2372

A violent explosion occurred during the ready interaction to produce alkyl nitrates.

Ammonia

MRH 6.61/33

Mellor, 1940, Vol. 8, 541

Liquid ammonia reacts explosively with the solid tetraoxide at —80°C, while aqueous ammonia reacts vigorously with the gas at ambient temperature.

Barium oxide

Mellor, 1940, Vol. 8, 545

In contact with the gas at 200°C the oxide suddenly reacts, reaches red heat and melts.

Boron trichloride

Mellor, 1946, Vol. 5, 132

Interaction is energetic.

Liquid mixtures proposed for use as explosives are stable up to 200°C [1], but can be detonated by mercury fulminate, and the vapours by sparking [2].

Carbonylmetals

Cloyd, 1965, 74

Combination is hypergolic.

Cellulose, Magnesium perchlorate

See Magnesium perchlorate: Cellulose, etc.

Cycloalkenes, Oxygen

Lachowicz, D. R. et al., US Pat. 3 621 050, 1971

Contact of cycloalkenes with a mixture of dinitrogen tetraoxide and excess oxygen at temperatures of 0°C or below produces nitroperoxonitrates of the general formula — CHNO₂—CH(OONO₂)—which appear to be unstable at temperatures above 0°C, owing to the presence of the peroxonitrate group.

See Hydrocarbons, below

Difluorotrifluoromethylphosphine

Mahler, W., Inorg. Chem., 1979, 18, 352

A reaction, to produce the phosphine oxide on 12 mmol scale, ignited.

Dimethyl sulfoxide

MRH 6.99/36

See Dimethyl sulfoxide: Dinitrogen tetraoxide

The slow (redox) reaction becomes explosive around 180°C [1], or even lower [2].

See other REDOX REACTIONS

Halocarbons

Mixtures of the tetraoxide with dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, trichloroethylene and tetrachloroethylene are explosive when subjected to shock of 25 g TNT equivalent or less [1]. Mixtures with trichloroethylene react violently on heating to 150°C [2]. Partially fluorinated chloroalkanes were more stable to shock. Theoretical aspects are discussed in the later reference [2,3]. The effect of pressure on flammability limits has been studied [4].

See Uranium: Nitric acid

See Vinyl chloride: Oxides of nitrogen

Heterocyclic bases

MRH Pyridine 7.82/22, quinoline 7.87/22

Mellor, 1940, Vol. 8, 543

Pyridine and quinoline are attacked violently by the liquid oxide.

See ROCKET PROPELLANTS

Hydrocarbons

MRH Benzene 7.99/19, hexane 7.91/17, isoprene 8.28/18, methylcyclohexane 7.87/17

A mixture of the tetraoxide and toluene exploded, possibly initiated by unsaturated impurities [1]. During attempted separation by low temperature distillation of an accidental mixture of light petroleum and the oxide, a large bulk of material awaiting distillation became heated by unusual climatic conditions to 50°C and exploded violently [2]. Subsequently, discussion of possible alternative causes involving either unsaturated or aromatic compounds was published [3,4,5,6,7]. Erroneous addition of liquid in place of gaseous nitrogen tetraoxide to hot cyclohexane caused an explosion [8]. During kinetic studies, one sample of a 1:1 molar solution of tetraoxide in hexane exploded during (normally slow) decomposition at 28°C [9]. Cyclopentadiene is hypergolic with the oxide [10]. These incidents are understandable because of their similarity to rocket propellant systems and liquid mixtures previously used as bomb fillings [11]. The liquid oxide leaking from a ruptured 6 t storage tank ran into a gutter containing toluene and a violent explosion ensued [12]. An alternative account describes the hydrocarbon as benzene [13].

See Cycloalkenes, above; Unsaturated hydrocarbons, below

Hydrogen, Oxygen

Lewis, B., Chem. Rev., 1932, 10, 60

The presence of small amounts of the oxide in non-explosive mixtures of hydrogen and oxygen renders them explosive.

Isopropyl nitrite, Propyl nitrite

Safety in the Chemical Laboratory, Vol. 1, 121, Steere, N. V. (Ed.), Easton (Pa.) J. Ch. Ed., 1967

A pressurised mixture of the cold components exploded very violently during a combustion test run. The mixture was known to be autoexplosive at ambient temperature, and both of the organic components are capable of violent decomposition in absence of added oxidant.

Laboratory grease

Arapava, L. D. et al., Chem. Abs., 1985, 102, 169310

Contact of the lubricating grease Litol-24 with the oxidant at below 80°C led to explosion on subsequent impact. This involved nitration products of the antioxidant present, 4-hydroxydiphenylamine. Above 80°C decomposition superceded nitration, and no explosion occurred.

See other NITRATION INCIDENTS

Metal acetylides or carbides

MRH values show % of oxidant

Mellor, 1946, Vol. 5, 849

Caesium acetylide ignites at 100°C in the gas.

See Tungsten carbide: Nitrogen oxides

MRH 4.02/63

Ditungsten carbide: Oxidants

MRH 3.85/67

Metals

Reduced iron, potassium and pyrophoric manganese all ignite in the gas at ambient temperature. Magnesium filings burn vigorously when heated in the gas [1]. Slightly warm sodium ignites in contact with the gas, and interaction with calcium is explosive [2].

See Aluminium: Oxidants

Nitroaniline

Anon., CISHC Chem. Safety Summ., 1978, 49, 3—4

Process errors led to discharge of copious amounts of nitrous fumes into the glass reinforced plastic ventilation duct above a diazotisation vessel. On two occasions fires were caused in the duct by vigorous reaction of the dinitrogen tetraoxide with nitroaniline dusts in the duct. Laboratory tests confirmed this to be the cause of the fires, and precautions are detailed.

Mixtures with nitrobenzene were formerly used as liquid high explosives, with addition of carbon disulfide to lower the freezing point, but high sensitivity to mechanical stimulus was disadvantageous [1]. During the recovery of acids from nitration of toluene, mixtures of the oxide with nitrotoluene or dinitrotoluene may be isolated under certain process conditions. While such mixtures are not unduly sensitive to impact, friction or thermal initiation, when oxygen-balanced they are extremely sensitive to induced shock and are capable of explosive propagation at film thicknesses below 0.5 mm. It is suspected that many explosions in TNT acid recovery operations, previously attributed to tetranitromethane, may have been caused by such mixtures [2].

Nitrogen trichloride

See Nitrogen trichloride: Initiators

Organic compounds

Riebsomer, J. L., Chem. Rev., 1945, 36, 158

In a review of the interaction of the oxidant with organic compounds, attention is drawn to the possibility of formation of unstable or explosive products.

Other reactants

Yoshida, 1980, 269

MRH values calculated for 18 combinations with oxidisable materials are given.

Ozone

See Ozone: Nitrogen oxide

Phospham

See Phospham: Oxidants

Phosphorus

MRH 9.12/35

See Phosphorus: Non-metal oxides

Sodium amide

Beck, G., Z. Anorg. Chem., 1937, 233, 158

Interaction with the oxide in carbon tetrachloride is vigorous, producing sparks.

Steel, Water

U.S. National Transportation Safety Board, Hazardous Materials Accident Brief,

Jan. 1998

A carbon steel tank for rail transportation of the tetroxide became contaminated with water, probably when a leaking valve, later replaced, was hosed down. After repair, the tank was charged with 50 tons of the oxide. This was later found to be wet, attempts were than made to empty the tanker. Acording to the single meter used to measure the transfer, this was accomplished (subsequent investigation suggested that only about 3 tons had been transferred because the dip pipes had corroded away). Water was charged to wash out the tank. The sequence of supposed emptying and washing was repeated and more water was added. It was noticed that pressure and fumes were excessive, atempts to deal with this continued some days. About a month after initial loading, and ten days after first washing, one of the heads blew off, throwing cladding about 100 m. Inspection of the remains showed several bands of corrosion, caused by nitric acid, produced from the oxide and water, reacting with steel to produce hydrogen and/or lower oxides of nitrogen which pressurised the weakened tank. Large tank cars are no longer used.

Tetracarbonylnickel

Bailar, 1973, Vol. 3, 1130

Interaction of the liquids is rather violent.

See Carbonylmetals, above

Tetramethyltin

Bailar, 1973, Vol. 2, 355

Interaction is explosively violent even at —80°C, and dilution with with inert solvents is required for moderation.

2-Toluidinium nitrate

Rastogi, R. P. et al., Indian J. Chem., Sect. A, 1980, 19A, 317—321

Reaction in this hybrid rocket propellant system is enhanced by presence of ammonium vanadate.

Triethylamine

Davenport, D. A. et al., J. Amer. Chem. Soc., 1953, 75, 4175

The complex, containing excess oxide over amine, exploded at below 0°C when free of solvent.

Triethylammonium nitrate

Addison, C. C. et al., Chem. & Ind., 1953, 1315

The two component form an addition complex with diethyl ether, which exploded violently after partial desiccation: an ether-free complex is also unstable.

See Triethylamine, above

Unsaturated hydrocarbons

Dinitrogen tetraoxide reacts explosively between —32° and —90°C with propene, 1-butene, isobutene, 1,3-butadiene, cyclopentadiene and 1-hexene, but 6 other unsaturates failed to react [1]. Reaction of propene with the oxide at 2 bar/30°C to give lactic acid nitrate was proceeding in a pump-fed tubular reactor pilot plant. A violent explosion after several hours of steady operation was later ascribed to an overheated pump gland which recently had been tightened. A similar pump with a tight gland created a hot-spot at 200°C [2].

See Nitrogen dioxide: Alkenes

Vinyl chloride

See Vinyl chloride: Oxides of nitrogen

Xenon tetrafluoride oxide

Christe, K. O., Inorg. Chem., 1988, 27, 3764

In the reaction of the pentaoxide with xenon tetrafluoride oxide to give xenon difluoride dioxide and nitryl fluoride, the xenon tetrafluoride oxide must be used in excess to avoid formation of xenon trioxide, which forms a sensitive explosive mixture with xenon difluoride dioxide.

See Xenon tetrafluoride oxide: Caesium nitrate

See other ENDOTHERMIC COMPOUNDS, NON-METAL OXIDES, OXIDANTS

Preparation of Labeled Samples

The latex was loaded with Fluoroprobe using 1,2-dichloroethane as carrier. The Fluoroprobe has been added to the aqueous latex as an emulsion in water by making use of Aerosol MA-80 surfactant (sodium dihexylsulfosuccinate, from American Cyanamid). Jeffamine T403, a multifunctional crosslinker containing primary amines, was labeled with modified Fluoroprobe, containing a maleimide functionality. The reaction occurred readily in ethanol; 1 % of the amino-functionality on Jeffamine was labeled. The Jeffamine was subsequently used in a curing reaction with a polyacrylate dispersion, equipped with acetoacetate groups. Aminogroups on functionalized silica spheres were labeled In 0.1 M sodiumhydrogencarbonate at room temperature during 2 h. In heterogeneous labeling reactions the excess label can be easily removed by application of a filtration procedure. The silica spheres have been functionalized with primary aminogroups, using γ-aminopropyltrlethoxysilane [12]. Aldehyde functionalities on latices were labeled by reaction in water at 40 °C. A reaction time of 3 hours is sufficient for quantitative conversion of the functional groups. Excess label was removed by extensive washing with methanol. The methanol was checked for any residual probe by measuring the fluorescence. The nylons have been labeled in m-cresol. Reaction is complete after 4 h at 50 °C.

8.24.1.6.2.3 Reaction media and catalyst recycling

The reaction carried out in THF or CF₃C₆F₁₁ in the presence of P(R_F)₃ or Cy₂PR_F gives a mixture of the four products, whereas the α-substituted product is cleanly formed in scCO₂/Cy₂P(R_F). Hydroboration of 2-vinylnaphthalene with PinBH catalyzed by [Rh(diphenylphosphinoethane (dppe))(cod)]BF₄ in the ionic liquid [Bu₄N]BF₄/scCO₂ is less selective, α/β 70:30.³⁶³

An alternative way of recycling the catalyst is to immobilize it on a solid support. A polymer-supported rhodium catalyst has been prepared by the copolymerization of ethylene glycol dimethyl acrylate and the p-isopropenylphenyl analog of [(nbd)Rh(dppe)]BF₄ 2% in the presence of dimethylformamide (DMF) used as a porogen.³⁶³ The polymer catalyst, 3 mol%, has been recycled three times in the hydroboration of styrene in THF, achieving 100% conversion and α/β 92:8. However, the combined crude materials from the three runs contain 4–5% of the Rh initially present in the polymeric catalyst.

In another approach, natural bentonites have been used as support of the asymmetric rhodium complex. The highest activities and enantioselectivities in the hydroboration of vinylarenes, competitive with the homogenous counterpart, have been obtained in the presence of (S)-QUINAP/Rh⁺X⁻, immobilized in predried MK-10 when X=BF₄, PF₆, and SO₃CF₃. The catalyst can be recycled and its important feature is the activity remaining even when manipulated in air between the runs.^379,380

The hydroboration of simple vinylarenes with CatBH catalyzed by rhodium complexes bound to the SiO₂-immobilized CH₂CHPPh₂ group (Si-DPP) affords preferentially the branched product.³⁸¹ In the presence of Rh(acac)(cod)₂ and Si-DPP (two equivalents), p-methoxy and p-fluorostyrene are transformed into the branched products with 100% regioselectivity. Styrene and 2-vinylnaphthalene react with the same excellent selectivity. The immobilized catalyst can be recycled with no significant loss of activity or selectivity. However, the reaction lacks selectivity with more hindered vinylarenes or when PinBH is used instead of CatBH.