Chlorophenoxy

Another appHcation of 4-chlorophenol is in the synthesis of a dmg, ethyl a, a-dimethyl-4-chlorophenoxy acetate [637-07-0] (60), used as a cholesterol-reducing agent. This synthesis involves reaction with acetone and chloroform, followed by ethanol esterification. 

Adenine, 9-(4-chlorophenoxy-2-hydroxypropyl)-biological activity, 5, 604 Adenine, 9-cyclohexyl-synthesis, 5, 585... 

TCDD is the most potent inducer of chloracne. This has been well known since the accident in Seveso, Italy, in 1976 in which large amounts of TCDD were distributed in the environment subsequent to an explosion in a factory that produced a chlorophenoxy herbicide, 2,4,5-T. TCDD is an impurity produced during the production of 2,4,5-T. The most common long-term effect of TCDD exposure was chloracne. Exposed individuals also suffered increased excretion of porphyrins, hyper-pigmentation, central nervous system effects, and liver damage and increased risk of cancer was a long-term consequence of the exposure. In addition to TCDD, polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans, and polychloronaphthalens cause chloracne as well as other effects typical of TCDD. 7i... 

The labeled aminopyridine 103 was further used for the synthesis of iV-(2-ethyl-3-chloro-4-pyiidin-2-yl-[ C]-4-(4-chlorophenoxy)phenylacetamide-[ C]-1)(98MI1). 

Chlorophenoxy acids are relatively polar pesticides which are usually determined by LC because volatile derivatives have to be prepared for GC analysis. This group of herbicides can be detected by multiresidue methods combined with automated procedures for sample clean-up, although selectivity and sensitivity can be enhanced by coupled-column chromatographic techniques (52). The experimental conditions for Such analyses are shown in Table 13.1. 

Figure 13.11 Column-switcliing RPLC trace of a surface water sample spiked with eight chlorophenoxyacid herbicides at the 0.5 p-g 1 level 1, 2,4-dichlorophenoxyacetic acid 2, 4-chloro-2-methylphenoxyacetic acid 3, 2-(2,4-diclilorophenoxy) propanoic acid 4, 2-(4-cliloro-2-methylphenoxy) propanoic acid 5, 2,4,5-trichlorophenoxyacetic acid 6, 4-(2,4-dichlorophenoxy) butanoic acid 7, 4-(4-chloro-2-methylphenoxy) butanoic acid 8, 2-(2,4,5-tiichlorophenoxy) propionic acid. Reprinted from Analytica Chimica Acta, 283, J. V. Sancho-Llopis et al., Rapid method for the determination of eight chlorophenoxy acid residues in environmental water samples using off-line solid-phase extraction and on-line selective precolumn switcliing , pp. 287-296, copyright 1993, with permission from Elsevier Science.

Chemical Name Equimolar mixture of Clofexamide which is 2-(p-chlorophenoxy)-N-[2-(diethylamino)Bthyl] acetamide with phenylbutazone... 

Chemical Name 2-(4-chlorophenoxy)-2-methylpropanoic acid ethyl ester Common Name Ethyl p-chlorophenoxylsobutyrate... 

Chemical Nama 2-Hydroxyethylnicotinate-2-(p-chlorophenoxy)-2-methyl propionate... 

A stream of ethylene oxide is passed through a solution of 107 g of 2-(p-chlorophenoxy)-2-methylpropionic acid and 2 g of zinc chloride in 200 ml of toluene, previously heated to between 55°C and 60°C, until 24 g of the gas have been dissolved. The reaction is allowed to continue for five hours, with gentle stirring. After this time has elapsed, the solution is cooled and washed successively with water, dilute ammonia and water until its pH becomes neutral. It is dried over anhydrous sodium sulfate, the solvent Is separated off under vacuum, and the resulting liquid is the monoglycol ester of 2-(p-chlorophenoxv)-2-methylpropionlc acid. 

To a solution of 93.8 g of the monoglycol ester in 500 ml of benzene, there are added 55 g of nicotinic acid chloride and 25 g of trimethylemine dissolved in 200 ml of benzene. The solution is stirred gently at a temperature of 60°C for two hours. After this time, the solution is cooled and washed successively with water, dilute hydrochloric acid, dilute ammonia and water until neutrality, it is dried over anhydrous sodium sulfate, and the sol vent Is evaporated under vacuum In this wey llOg of glycol 2-(p-chlorophenoxy)-2-methylpropionate nico-tlnate Is prepared, which represents a yield of 84%. The product is a sllghly yellow oil having a refraction index of no = 1.5422 and which is distilled with decomposition et 214°C at a pressure of 0.3 mm. 

Chemical Name 1-(Theophyllin-7-yl)ethyl 2-(p-chlorophenoxy)isobutyrete... 

The residue was then crystallized from isopropanol, yielding 58.0 g (55% yield) of 1 -(7-theo-phyllinyl)-2-athyl [2-(p-chlorophenoxy)-isobutyrate]. The compound had a melting point of 131°Cto 132°C. 

The ether extract is separated, dried over sodium sulfate, and evaporated to an oily residue (40 g) which contains ethyl o-(p-chlorophenoxy) carbanilate and is used without further purification. The crude ethyl o-(p-chlorophenoxy)carbanilate is dissolved in 20 ml of benzene, and 20 ml of 1-methylpiparazine and a small amount of sodium methylate (approximately 25 to 50 mg) are added. Benzene is then removed by slow distillation and the mixture is heated overnight under reflux (approximately 16 hours). 

A mixture of 4-methyl-2 -(p-chlorophenoxy)-1-piperazinecarboxanilide hydrochloride (6 g), 50 ml of phosphorus oxychloride and 10 g of phosphorus pentoxide is heated under reflux for about 24 hours, and then concentrated to a gummy residue by evaporation under reduced pressure. This residue is taken up in 150 ml of ether, 200 g of ice is added, and the mixture is made basic with concentrated aqueous ammonium hydroxide. The ether layer is separated, dried over potassium hydroxide pellets and evaporated to a solid residue (approximately 4 g). 

A mixture of 22 grams of Oi-(p-chlorophenoxy)isobutyric acid, 3.8 grams of 1,3-propane-dioi, 0.5 gram of p-toiuenesulfonic acid and 150 ml of xylene was refluxed. When the theoretically calculated amount of water had been removed, the xylene solution was washed with dilute aqueous sodium bicarbonate and then the xylene was distilled off. The residue was distilled under reduced pressure to give 11 grams (47% yield) of 1,3-propanediol bis[a-(p-chlorophenoxy)isobutyrate] boiling at 197° to 200°C/0.03 mm Hg. 

Bephenium hydroxy nephthoate a-(p-Chlorophenoxy)isobutyric acid Clofibrate... 

A series of 2-(4-chlorophenoxy)-3-oxoalkanoate were reduced by baker s yeast, and Kluyveromyces marxianus. Yeast reduction of ethyl 2-(4-chlorophenoxy)-3-oxo-3-phenylpropanoate (R=Ph) afforded enantiomerically pure ethyl 2R, 3S)-2-(4-chlorophenoxy)-3-hydroxy-3-phenylpropanoate out of the four possible stereoisomers in >99% de [29h]. Although baker s yeast reduction of butanoate (R = CFl3) was not selective (92% de), the use of K. marxianus afforded (2R, 3S)-isomer selectively [29i]. The products are intermediates for potential peroxisome prolifera-tor-activated receptor isoform a-agonists (Figure 8.39a). 

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