Iodobenzene dichloride, preparation

Iodoxybenzene has been prepared by the disproportionation of iodosobenzene,4Hi by oxidation of iodosobenzene with hypo-chlorous add or bleaching powder,7 and by oxidation of iodobenzene with hypochlorous acid or with sodium hydroxide and bromine.8 Other oxidizing agents used with iodobenzene include air,3 chlorine in pyridine,9 Caro s acid,19-11 concentrated chloric acid,15 and peracetic acid solution.13 Hypochlorite oxidation of iodobenzene dichloride has also been employed.14... 

Iodobenzene dichloride has always been prepared by direct combination of iodobenzene and chlorine in the presence of chloroform.1... 

Iodosobenzene has been prepared by the action of aqueous sodium or potassium hydroxide upon iodobenzene dichloride 2 and by repeated additions of water to iodobenzene dichloride.3... 

In a 1-1. three-necked flask, protected from the light and equipped with a mechanical stirrer, an inlet tube for the introduction of chlorine (Note 1), and an exit tube carrying a calcium chloride drying tube, are placed 150 cc. of dry chloroform (Note 2) and 102 g. (0.5 mole) of iodobenzene (Org. Syn. 19, 55). The flask is cooled in an ice-salt mixture, and dry chlorine (Note 3) is introduced, as rapidly as the solution will absorb it, until an excess is present (usually about three hours is required). The yellow, crystalline iodobenzene dichloride is filtered with suction, washed sparingly with chloroform, and dried in the air on filter paper. The yield is 120-134 g. (87-94 per cent of the theoretical amount) (Notes 4 and 5). The product is quite pure and may be used directly for the preparation of iodosobenzene and iodoxy-benzene. Since iodobenzene dichloride decomposes slowly on standing, it should not be stored indefinitely. 

The recovered iodobenzene is quite pure and may be used for the preparation of iodobenzene dichloride. The recovery is about 46 g. (90 per cent of the theoretical amount). 

In a 2-1. round-bottomed flask equipped with an efficient mechanical stirrer (Note 1) are placed 110 g. (0.4 mole) of freshly prepared, pulverized iodobenzene dichloride (jp. 69) (Note 2), 1.0 mole of sodium hypochlorite solution (Note 3), and 2 cc. of glacial acetic acid. The vigorously stirred mixture is heated on a water bath maintained at 65-75°. After ten to fifteen minutes the heated mixture becomes frothy and the yellow color of iodobenzene dichloride is displaced by the white color of iodoxybenzene. The stirring is stopped after one hour, and the flask is cooled in an ice bath. The product is filtered with suction,... 

Limonene (88) is known to react with one or two equivalents of hydrogen chloride the monohydrochloride (105) is conveniently prepared in carbon disulphide. The dihydrochloride (106) reacts with chlorine in a complex way Carman and Venzke have shown how the trichloride (107) and tetrachloride (108) are formed, the latter being identical with the product obtained from terpinolene (89) and iodobenzene dichloride. Zinc-alcohol reduction of the tetrachloride leads to the 1,2-cts-dichloride (109), which will, in turn, add hydrogen chloride to give a second trichloride (110). " Carman and Venzke have shown that the... 

A second method is by hypochlorite oxidation of freshly prepared, pulverized iodobenzene dichloride. A mixture of 0.4 mole of dichloride and 1 mole of commercial sodium hypochlorite solution (1.15 I. of Chlorox) and 2 ml. of acetic acid is... 

The Beecham group found that thiols add readily to the double bond of C(2)-unsubstituted 1-carbapenems, and this approach has been used to synthesise racemic PS-5 130). The A -silylated 4-allylazetidinone (157) was alkylated with ethyl iodide and the product (158) transformed to the phosphorane (159). Cyclisation to (1 ) was followed by reaction with acetamidoethane thiol to form three isomers of the addition product (161). These could be converted to the carbapenem (162) on reaction with iodobenzene dichloride in the presence of pyridine. Isomerization to (163) and deprotection afforded the racemic natural product. The ester (163) has also been prepared via the diazo-intermediate (164) derived from the 4-acetoxy azetidinone (165) 131). A total synthesis of chiral PS-5 has been achieved using the resolved acid (166) (132). This was converted to (164) and then to optically pure PS-5. It has also been possible to synthesise PS-5 and PS-7 from the olivanic acid derivatives MM 17880 and MM 13902 133). The benzyl ester of ( )-MM 22381 was obtained from the azabicyc-loheptane (167) derived from the addition of acetamidoethane thiol to the appropriate C(2)-unsubstituted nucleus 108). 

Willgerodt4 prepared iodosobenzene diacetate by adding chlorine to iodobenzene and hydrolyzing the dichloride to iodosobenzene, which was then reacted with acetic acid. Pausacker 6 used this method to synthesize a number of analogs but found it... 

Preparation. The reagent is prepared by stirring iodosobenzene diacetate with iN sodium hydroxide, collecting and drying the solid, and macerating it with chloroform to remove a little iodobenzene. This procedure is preferable to an older one involving alkaline hydrolysis of iodosobenzene dichloride because iodoso-... 

For alkylation of phosphines containing C-H bonds their alkali salts are usually treated with alkyl halides. Thus primary and secondary phosphines can be obtained by metalation of phosphine itself with sodium in liquid ammonia and subsequent alkylation 208 phosphirane, which is unstable, is also prepared in this way, from sodium phosphide and ethylene dichloride.209 High yields of primary phosphines are afforded by alkylating lithium phosphide, which is formed almost quantitatively by metalating phosphine with butyl-lithium.210 Since the hydrogen can be replaced stepwise by metal, unsymmetrical secondary and tertiary phosphines can be built up from PH3 or a primary phosphine.211 Use of alkali phosphides is not limited to alkylation potassium diphenylphosphide reacts quantitatively with iodobenzene, yielding triphenyl-phosphine.212... 

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