3-Dichlorophenol

After exposure at 10,000 ppm on days 6 through 15 of gestation, 15 of 25 pregnant female rats had no viable femses or implantation sites on the uterine walld 

The 2003 ACGIH threshold limit valuetime-weighted average (TLV-TWA) for dichlorofluoromethane is lOppm (42mg/m ). 

Trochimowicz HJ et al Ninety-day inhalation toxicity studies on two fluorocarbons. Toxicol Appl Pharmacol 41 299 (abst), 1977 

Dichlorofluoromethane. Documentation of TLVs and BEIs, 6th ed, pp 434-435. Cincinnati, OH, American Conference of Governmental Industrial Hygienists, 1991 

Toxieology. 1,1-Dichloro-l-nitroethane is a pulmonary, skin, and eye irritant in animals it is expected that severe exposure will cause the same effects in humans. 

Submitted by D. S. Tarbell, J. W. Wilson, and Paul E. Fania. Checked by R. L. Shbinee and Arne Langsjoen. 

6-Dichlorophenol. A mixture of 250 g. (1.2 moles) of dry 3,5-dichloro-4-hydroxybenzoic acid and 575 g. (600 ml., 4.8 moles) of redistilled dimethylaniline is placed in a 2-1. round-bottomed flask provided with a thermometer and a short aircooled condenser and is heated slowly in an oil bath. Evolution of gas commences at 130° and is vigorous at 150°. The solution is heated at 190-200° for 2 hours or until the evolution of gas has ceased. After cooling, the solution is poured by portions into 600 ml. of concentrated hydrochloric add in a 3-1. separatory funnel, with cooling from litne to lime by holding the funnel under a stream of cokl water. When the solution is 

The ethyl 4-hydroxybenzoate was obtained from the Eastman Kodak Company and melted at 115.5-116°. 

If the product weighs much less than 350 g. at this point, an additional 50 ml. of sulfuryl chloride should be added and the heating continued until gas is no longer evolved. 

The ester crystallizes from dilute alcohol as the monohydrate after long drying in a vacuum desiccator over phosphorus pentoxide, it melts at 111-112°. 

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In addition to the Hquid—Hquid reaction processes, there are many cases in both analytical and industrial chemistry where the main objective of separation is achieved by extraction using a chemical extractant. The technique of dissociation extraction is very valuable for separating mixtures of weakly acidic or basic organic compounds such as 2,4-dichlorophenol [120-83-2] and 2,5-dichlorophenol [583-78-8] which are difficult to separate by... 

The reductive dechlorination of chlorinated aromatics is more compHcated in that the initial dechlorination of more highly chlorinated compounds may be either chemical or enzymatic, eg, PGP, whereas the dechlorination of less chlorinated compounds or dechlorinated products is typically enzymatic. For example, the first dechlorination of 2,4-dichlorophenol (ortho position) can occur either chemically or enzymatically the second dechlorination (para position) is enzymatic (eq. 10). 

Dichlorophenols. Among all the dichlorophenols, C H Cl O, it is 2,4-dichlorophenol that is produced in greatest quantity. 2,4-Dichlorophenol is used in manufacturing 2,4-dichlorophenoxyacetic acid [94-75-7] (2,4-D) and 2-(2,4-dichlorophenoxy)propionic acid [720-36-5] (2,4-DP). Industrially, 2,4-dichlorophenol can be obtained by chlorinating phenol, -chlorophenol, o-chlorophenol, or a mixture of these compounds in cast-iron reactors. The chlorinating agent may be chlorine or sulfuryl chloride in combination with a Lewis acid. For example ... 

Chlorination with SO2CI2, which is favorable to the para isomer at the monochlotination stage, gives an excellent yield of 2,4-dichlorophenol. Startiag with (9-chlorophenol, it is possible to attain a selectivity for 2,4-dichlorophenol of 98%, if chlotination is carried out ia Hquid SO2 at low temperature (20). 2,6-Dichlorophenol is also used as an iatermediate. It is obtained by chlotinatiag o-chlorophenol ia the presence of a catalytic quantity of an amine, with or without a solvent medium (21,22), giving a yield of 90%. 

In the chlorination of 2,4-dichlorophenol it has been found that traces of amine (23), onium salts (24), or triphenylphosphine oxide (25) are excellent catalysts to further chlorination by chlorine ia the ortho position with respect to the hydroxyl function. During chlorination (80°C, without solvent) these catalysts cause traces of 2,4,5-trichlorophenol ( 500 1000 ppm) to be transformed iato tetrachlorophenol. Thus these techniques leave no 2,4,5-trichlorophenol ia the final product, yielding a 2,4,6-trichlorophenol of outstanding quaUty. The possibiUty of chlorination usiag SO2CI2 ia the presence of Lewis catalysts has been discussed (26), but no mention is made of 2,4,5-trichlorophenol formation or content. 

Dow produces 2,4-dichlorophenol chiefly for a captive market ia the United States and Bra2il. 

In addition to the use of 2,4-dichlorophenol in the synthesis of 2,4-D herbicides (acid 2,4-D, acid 2,4-DP, acid 2,4-DB), it is also found in the selective post-emergence herbicide, diclofop-methyl [51338-27-3] (61) and as a selective pre-emergence herbicide, oxadia2on [19666-30-9] (62). A postemergence herbicide is appHed between the emergence of a seedling and the maturity of a crop plant. 

Dichlorophenol [120-83-2] M 163.0, m 42-43°, pK 7.89. Crystd from pet ether (b 30-40°). Purified by repeated zone melting, using a P2O5 guard tube to exclude moisture. Very hygroscopic when dry. 

The lens is an avascular transparent tissue surrounded by an elastic, collagenous capsule. Disturbances in the normal metabolism of the lens and rupture of the lens alter its optical characteristics, and may cause cataract, i.e., reduced transparency of the lens. For example exposure to a herbicide, 2,4-dichlorophenol, may cause cataract. 

In addition lo its use in making resins and adhesives, phenol is also the starting material for the synthesis of chlorinated phenols and the food preservatives BHT (butylated hvdroxytoiuene) and BHA (butylated bydroxyanisole). Penta-chlorophenol, a widely used wood preservative, is prepared by reaction of phenol with excess CI2- The herbicide 2,4-D (2,4-dichlorophenoxyacetjc acid) is prepared from 2,4-dichlorophenol, and the hospital antiseptic agent hexa-chlorophene is prepared from 2,4,5-trichlorophenol. 

Phenol 2,4,6-trichlorophenol p-chloro-m-cresol 2-chlorophe-nol 2,4-dichlorophenol 2,4,-dimethylphenol 2-nitrophenol 4-nitrophenol 2,4-dinitrophenol and pentachlorophenol... 

The interpretation of the above data on iodination has been questioned by Buss and Taylor217, and by Grovenstein et a/.218,219. The former workers studied the iodination of 2,4-dichlorophenol at about 25 °C using a stirred flow reactor, the advantages of which are that once a steady state has been reached there is no change in the concentration of the reactive species in the reactor with time and the rate of reaction is simply a product of extent of reaction multiplied by the reciprocal ol the contact time hence it is possible to use unbuffered solutions and low iodide ion concentrations. They found general catalysis by the base component of added phosphate buffers and the observed rate coefficients varied with [H+ ] according to... 

Uniformly labeled 2,4-dichlorophenol- C (purchased from New England Nuclear Corp, Boston, Mass.) was used in the tracer preparation. This provided a label at all carbon positions in the dibenzo-dioxin structure. 2,7-Dichlorodibenzo-p-dioxin- C after initial cleanup by fractional sublimation, contained approximately 5% of an impurity, detected by thin layer chromatography (TLC) which gave mass peaks at 288, 290, 292, and 294 in the mass spectrometer, consistent with a trichloro-hydroxydiphenyl oxide. This is probably the initial condensation product of the Ullman reaction and is most likely 2-(2,4-dichlorophenoxy)-4-chlorophenol. It was removed easily by extractions with aqueous... 

Chlorinated dibenzo ip-dioxins are contaminants of phenol-based pesticides and may enter the environment where they are subject to the action of sunlight. Rate measurements showed that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is more rapidly photolyzed in methanol than octachlorodi-benzo-p-dioxin. Initially TCDD yields 2,3,7-trichlorodiben-zo-p-dioxin, and subsequent reductive dechlorination is accompanied by ring fission. Pure dibenzo-p-dioxin gave polymeric material and some 2,2 -dihydroxybiphenyl on irradiation. Riboflavin-sensitized photolysis of the potential precursors of dioxins, 2,4-dichlorophenol and 2,4,5-trichloro-phenol, in water gave no detectable dioxins. The products identified were chlorinated phenoxyphenols and dihydroxy-biphenyls. In contrast, aqueous alkaline solutions of purified pentachlorophenol gave traces of octachlorodibenzo-p-dioxin on irradiation. 

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