Halogen/alkali hydroxide

Because of the fact that the halogen is so very firmly attached to the benzene ring, the hydrolysis of chlorobenzene, a cheap substance, can only be carried out according to the following equation at very high temperatures and then with dilute solutions of alkali hydroxide (K. H. Meyer and F. Bergius). 

These compounds, which may be considered as chloroanhydrides of alkylsulphuric adds, have little stability. They are readily decomposed by cold water or by the action of the alkali hydroxides with splitting off of the halogen and formation of the alkyl sulphuric acids ... 

Hydroxymercuri methyl malonic ester, H0Hg.CMe(C02Me).2, is saponified with 4 mols. of Normal alkali hydroxide and the resulting solution acidified by dilute sulphuric acid. The precipitate is washed, suspended in water and boiled until the evolution of carbon dioxide ceases, a nearly quantitative yield of ester being obtained. It decomposes at 150° C., and with halogen acids yields mercuric salts. It is insoluble in organic solvents, but dissolves readily in alkalies. 

Of the three oxides only ZnO is amphoteric, the other two are purely basic. Thus zinc forms the most stable complex anion with oxygen, and mercury the most stable complex ions with the halogens. The hydroxides of zinc and cadmium are obtained as crystalline precipitates on the addition of alkali to solutions of the nitrates a hydroxide of mercury is unknown. 

ZIRCAT (7440-67-7) Finely divided material is spontaneously flammable in air may ignite and continue to bum under water. Violent reactions with oxidizers, alkali hydroxides, alkali metals (and their compounds), carbon tetrachloride, cupric oxide, lead, lead oxide, lead peroxide (combined material can burn explosively, and is sensitive to friction and static electricity), nitryl fluoride, oxygen difluoride, phosphoms, potassium, potassium compounds (potassium chlorate, potassium nitrate), sodium borate, sodium hydroxide. Explodes if mixed with hydrated borax when heated. Contact with lithium chromate may cause explosion above 752°F/450°C. Forms explosive mixture with potassium chlorate. Dusts of zirconium ignite and explode in a carbon dioxide atmosphere. Contact with ammonium-V-nitrosophenylhydroxylamine above 104°F/40°C forms an explosive material. Incompatible with boron, carbon, nitrogen, halogens, lead, platinum, potassium nitrate. In case of fire, use approved Class D extinguishers or smothering quantities of dry sand, crushed limestone, clay. 

Lustrous, silver-white surface (when freshly cut) face-centered cubic structure below 300 C. Ignites in air when finely divided, then burns with crimson flame. Much harder than sodium, but softer than aluminum or magnesium. Acquires bluish-gray tarnish on exposure to moist air. dj° 1.54. mp 85C. bp 1440. Electrical resistivity at 20 3.5 ohm cm. Brinell hardness 17. Heat of combustion 15l.9cal/g. sp ht (0-100 ) 0,149 cal/g. Considerably less reactive than sodium. E (aq) CaJ + /Ca —2.87 V. Reacts with water, alcohols, and dd acids with evolution of hydrogen. Reacts with halogens. Dissolves in liquid ammonia to form a blue soln. Contact with alkali hydroxides or carbonates may cause detonation. Bums in air. Calcium salts impart brick red color to a flame. Insol in and inert towards benzene, kerosene. 

The halogen of trihalides may be replaced analogously to that of mono- and gew-di-halides, no new considerations being involved. The usual reagents are slaked lime at 50°, alcoholic alkali hydroxides, acids, or iron(m) chloride in aqueous solution. Some trichloromethyl compounds are converted into carboxylic acids in excellent yield by heating them in chloroform in the presence of anhydrous iron(m) chloride whilst the appropriate amount of water is dropped in.549... 

The dehalogenating agent may be a metal such as copper, magnesium, zinc, aluminum, iron, or an alkali metal, etc., or may be an alkali hydroxide or alkali iodide in ethanol or acetone. The removal of halogen generally liberates a considerable amount of heat, so that presence of a solvent is advisable.65... 

Choline876 and potassium amide877 have also given good results as dehydro-halogenating agents. Nitro- and cyano-benzyl chlorides are mostly converted very smoothly into stilbene derivatives when treated with alcoholic alkali hydroxide, as exemplified by Walden and Kernbaum for 4,4 -dinitrostilbene 878... 

CHEMICAL PROPERTIES Red AT (500°F) ignites at boiling point reacts only at high temperatures less reaetive than white phosphorus White AT (86°F) spontaneously ignites in air reaets with sulfur, halogens, metals, nitrie acid, alkali hydroxides ineompatible with iodine, oil or turpentine and potassium chlorate. 

CHEMICAL PROPERTIES flammable solid volatile ignites at about 30 C in moist air forms tri- or pentahalides on direct combination with the halogens combines with sulfur to form sulfides reacts with several metals to form phosphides treatment with nitric acid yields orthophosphoric acid reaction with alkali hydroxides leads to the formation of phosphine and sodium hypophosphite FP (spontaneously flammable in air) LFLAJFL (NA) AT (30 C, 86°F). 

Pyrazoles either do not react with nucleophiles, or react with them only very slowly. For instance, pyrazoles unsubstituted in the 3-position undergo ring opening on heating with alkali hydroxides. Nucleophilic substitution of a halogen in halopyrazoles is also difficult. 

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