4-Chlorobenzenediazonium chlorid

Stronger reducing agents than Cu1 can be used for reactions that are related to the classical Meerwein reaction. Tim salts not only catalyze the formation of aryl radicals from diazonium ions but, as shown by Citterio and Vismara (1980) and Cit-terio et al. (1982 a), in stoichiometric proportions they also reduce the primary aryl-ethane radical to the arylethyl anion, which is finally protonated by the solvent SH (Scheme 10-61). This method is the subject of a contribution to Organic Syntheses (Citterio, 1990), in which 4-(4 -chlorophenyl)buten-2-one is obtained in 65-75% yield from 4-chlorobenzenediazonium chloride and but-3-en-2-one. 

Besides two older examples of classical Meerwein reactions156, there is a more recent description of the reaction of 4-chlorobenzenediazonium chloride with but-3-en-2-one, catalyzed by Tinl in stoichiometric proportions. This method was developed by Citterio and gives 4-(4 -chlorophenyl)but-3-en-2-one in 65-75% yield. 

N 37.75% yel crysts(from ale), reported as brn solid by Bekhli et al(Ref 4), mp-dec at 136-4 0° on heating slowly, explodes mildly on heating rapidly between 15 0-60° was first prepd by Walther Grieshammer (Refs 1 2) from reaction of 4 Chlorobenzenediazonium chloride dicyanodiamide in alk soln. It was later prepd by others (Refs 3, 4, 5 6).Some of its salts are mild expls Refs l)Beil 16, (4 05) 2)R. von Walther ... 

The carbocyclic nucleoside analogs 342-344 were prepared by diazo coupling of (lJ mJ-S-pyrimidylaminomethyl-l -trimethylcyclopentyl-methanol (339) with 4-chlorobenzenediazonium chloride to give 340, which upon reduction gave the triamine 341. Ring closure of 341 with nitrous acid gave (17 ,c/s)-3-[(5-amino-7-chloro-3//-l,2,3-triazolo[4,5-d]pyrimidin-3-yl)-... 

The 4-chlorobenzenediazonium chloride solution is prepared as follows finely powdered 4-chloroaniline (5.65 g, 0.044 mol) is suspended 1n 18 mL of 24% aqueous hydrochloric acid and cooled to 0 C. Sodium nitrite (3.2 g, 0.046 mol) in water (7 ml) is added dropwise during 45 m1n at 0-5°C to give a pale yellow solution of the diazonium salt. 

Chlorobenzenediazonium chloride underwent smooth coupling with A -(benzofuran-2-ylcarbonylmethyl)pyridi-nium bromide 62 to give the amidrazonium salt 63. Heating of compound 63 with ammonium acetate in acetonitrile furnished the l,4-dihydro-l,2,4,5-tetrazine derivative 64 in 60% yield (Scheme 15) <2006AP133>. 

Interaction of 2-, 3- or 4-chlorobenzenediazonium salts with (9-alkyldithiocarbon-ate ( xanthate ) solutions [8] or thiophenoxide solutions [9] produces explosive products, possibly arenediazo aryl sulfides. The intermediate diazonium xanthate produced during the preparation of m-thiocresol can be dangerously explosive under the wrong conditions [8], while the reaction of 3-nitrobenzenediazonium chloride with xanthate solution at 70—75°C proceeds with near-explosive evolution of nitrogen [4]. The product of interaction of 2-chlorobenzenediazonium chloride and sodium 2-chlorothiophenoxide exploded violently on heating to 100°C, and the oil... 

Fischer and Zollinger have studied the reaction of p-chlorobenzenediazonium chloride with 2-naphthol-l-sulfonate. A very interesting dependence of the reaction products and reaction rate on the solvent was observed The initiaUy formed complex 102 decomposes under ring fragmentation in aqueous base (see (44) in Sect. 2.2.3) it does not react in water, ethanol or dimethylsulfoxide, reacts very slowly in acetone or glacial acetic acid to give a small amount of azo compound 7dJ, while in dichloromethane, chloroform, benzene or pyridine quantitative, though slow, formation of the azo compoimd is observed. Ba on kinetic measurements an Sisil-type mechanism was postulated for the formation of the azo dye 103 from the CT-complex 102... 

Meerwein and his co-workers469 found that p-chlorobenzenesulfonyl chloride476 can be obtained from p-chlorobenzenediazonium chloride in liquid sulfur dioxide containing copper(i) chloride, and his school later elaborated... 

Hantzsch, who put forward this hypothesis as to the way in which diazonium compounds undergo decomposition, has isolated in the case of certain diazonium derivatives the intermediate s2/n-diazo compounds. When p-chlorobenzenediazonium chloride, CIC6H4N2CI, is treated with a cyanide, p-chlorobenzo-nitrile, CIC6H4CN, is not immediately formed. The resulting product reacts energetically when treated with copper-powder and nitrogen and the nitrile are formed. This intermediate compound is considered to be the syn-diazo cyanide, as it does not possess the properties of diazonium salts. The syn-compound is unstable and on standing is converted into an isomer, which does not react with copper-powder this appears to be the anti-diazo compound. 

Glutazine (IX-99) reacts with p-chlorobenzenediazonium chloride to give IX-100. 4-Amino-2,6-dichloropyridine is prepared in 60% yield from the reaction of glutazine with phosphorus oxychloride at 150° for 5 hours. ... 

DIMETHYL SULFIDE (75-18-3) C,HjS Highly flammable liquid. Vapor forms explosive mixture with air [explosion limits in air (vol %) 2.2 to 19.7 flash point -36°F/-38°C autoignition temp 403°F/206°C Fire Rating 4]. Reacts wifli water, steam, acids, and acid fumes producing hydrogen sulfide fumes, which can explode in air. Reacts violently with strong oxidizers, chlorobenzenediazonium salts, mercurous chloride oxygen (explosive... 

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