23.4.5.6- Pentachloro

In the presence of catalysts, trichloroethylene is readily chlorinated to pentachloro- and hexachloroethane. Bromination yields l,2-dibromo-l,l,2-trichloroethane [13749-38-7]. The analogous iodine derivative has not been reported. Fluorination with hydrogen fluoride in the presence of antimony trifluoride produces 2-chloro-l,l,l-trifluoroethane [75-88-7] (8). Elemental fluorine gives a mixture of chlorofluoro derivatives of ethane, ethylene, and butane. 

Chlorination of 2,6-dichlorophenol by chlorine at 70°C gives a yield of only 85%. Fifteen percent of the mixture is made up of 2,4,5,6,6-pentachloro-2-cyclohexen-l-one, the formation of which can be explained by the foUowiag mechanism ... 

The chlorination of 45 in an acetic acid-acetic anhydride mixture leads to a pentachloro-acetoxy compound (49), but in acetic... 

Chlorination. Electrophilic chlorination of quinoline (66) in neutral medium showed a positional selectivity order of 3 > 6 > 8. The 5- and 8-positions should be sterically hindered to some extent. Hammett cr+ values predict an order for electrophilic substitution of 5 > 8 = 6 > 3. Treatment with chlorine at 160-190°C converted quinoline into a mixture of 3-chloro-, 3,4-dichloro-, 3,4,6- and 3,4,8-trichloro-, 3,4,6,8-tetrachloro-, and 3,4,6,7,8-pentachloro-quinolines. At lower temperatures ( 100°C) the major product was 3-chloroquinoline, albeit in low yield. The 4-substituted species may have arisen from an addition-elimination or radical process (70JHC171). 

Vanadate, dioxybis(oxamato)-bond-length ratios, 1,57 Vanadate, heptacyano-potassium salt structure, I, 72 Vanadate, hexafluoro-dipotassium salt history, I, 21 potassium salt history, 1,21 tripotassium salt history, 1,21 Vanadate, pentachloro-stereochemistry, 1,40 Vanadate, pentafluorooxy-stereochemistry, I, 50 Vanadates biochemistry, 3,456 calcium/magnesium ATPase inhibition, 6, 567 competition with phosphates physiology, 6,665 protonation, 3,1026 sodium pump, 6, 557 in uranium purification from ore, 6, 899 Vanadates, hexafluoro-, 3. 482,531 Vanadates, oxoperoxo-, 3,501 Vanadates, pentacarbonyl-, 3, 457 Vanadium biology, 6,665 determination, 1. 548 extraction... 

Water hydrolyzes diethyl phosphorochloridate [chloro-diethoxyphosphorus(V) oxide] readily but does not affect the diene. Alternatively, the reaction mixture can be processed by fractionation. Evaporation of the petroleum ether and fractionation of the residue through a 25-cm. x 2.2-cm. column of glass helices yields 170 g. (98.5%) of diethyl phosphorochloridate, b.p. 34-36°/0.2 mm., d 1.4210-1.4250 (the refractive index indicates that it contains 5-10% of the title compound), and 240-255 g. (90-96%) of l,2,3,4,5-pentachloro-5-ethylcyclo-pentadiene, b.p. 51-53°/0.2 mm., 1.5398. 

The reaction mixture can also be processed by chromatography. The crude reaction mixture is poured on a 90-cm. x 4.5-cm. column of alumina (e.g, Fisher adsorption grade ) and eluted with about 2 1. of technical-grade pentane. This yields a pale-yellow solution that is free of diethyl phosphorochloridate. Evaporation of the pentane gives 240-255 g. (90-96%) of l,2,3,4,5-pentachloro-5-ethylcyclopentadiene. 

Ethylene carbonate, reaction with potassium thiocyanate, 42, 59 Ethylene sulfide, 42, S9 Ethyl formate, reaction with cyclo-hexylamine, 41, 14 Ethyl- -hexylamine, 43, 47 5-(2-Ethylhexyl)-l,2,3,4,5-pentachloro-cyclopentadiene, 43, 93 Ethylhydrazinium hydrogen oxalate,... 

Hexachlorocyclopentadiene, ethylation to l,2,3,4,5-pentachloro-5-ethyl-cyclopentadiene, 43, 90 Hexadecanedioic acid, 43, 39... 

Pentachloro-5-ethylcyclo-pentadiene, 43, 90 Pentacyanopropenc, 41,100 acid strength of, 41, 100 Pentane, 2,2,4-trim ethyl-4-nitro, 43, 87... 

Phosphorous pentachloride Phosphorus chloride (PCI5) (8) Phosphorane, pentachloro- (9) (10026-13-8)... 

Dichlorodibenzo-p-dioxin was prepared from isotopic potassium 2,4-dichlorophenate uniformly labeled with Ullman conditions gave a 20.5% yield. Small amounts of dichlorophenoxy chlorophenol were removed from the product by extraction with sodium hydroxide before purification by fractional sublimation and recrystallization from anisole. Chlorination of 2,7-dichlorodibenzo-p-dioxin in chloroform solution containing trace amounts of FeCls and 12 yielded a mixture of tri-, tetra-, and pentachloro substitution products. Purification by digestion in boiling chloroform, fractional sublimation, and recrystallization from anisole was effective in refining this product to 92% 2,3,7,8-tetrachloro isomer, which also contained 7% of the tri- and 1% of the penta-substituted dibenzo-p-dioxin. Mass spectroscopy was used exclusively to monitor the quality of the products during the synthesis. 

So a compound wifh five chlorine atoms would be pentachloro. Each and every substituent needs to be numbered so that we know where it goes on the parent chain, but we will learn about this after we have finished going through the five parts of the name. At that time, we will also discuss in what order to place substituents in the name. 

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