Chlorides general preparation

Thiazolecarboxylic acid chlorides, generally prepared from the corresponding acid and thionyl chloride (Scheme 13), are relatively unstable (2,... 

Meanwhile, during the cooling of the cuprous chloride solution, prepare a solution of benzenediazonium chloride by dissolving 20 ml. (20-5 g.) of aniline in a mixture of 50 ml. of concentrated hydrochloric acid and 50 ml. of water, and after cooling to 5°, adding slowly a solution of 17 g. of sodium nitrite in 40 ml. of water. Observe carefully the general conditions for diazotisation given in the preparation of iodobenzene (p. 184). 

Stannic and stannous chloride are best prepared by the reaction of chlorine with tin metal. Stannous salts are generally prepared by double decomposition reactions of stannous chloride, stannous oxide, or stannous hydroxide with the appropriate reagents. MetaUic stannates are prepared either by direct double decomposition or by fusion of stannic oxide with the desired metal hydroxide or carbonate. Approximately 80% of inorganic tin chemicals consumption is accounted for by tin chlorides and tin oxides. 

Solutions of anhydrous stannous chloride are strongly reducing and thus are widely used as reducing agents. Dilute aqueous solutions tend to hydrolyze and oxidize in air, but addition of dilute hydrochloric acid prevents this hydrolysis concentrated solutions resist both hydrolysis and oxidation. Neutralization of tin(II) chloride solutions with caustic causes the precipitation of stannous oxide or its metastable hydrate. Excess addition of caustic causes the formation of stannites. Numerous complex salts of stannous chloride, known as chlorostannites, have been reported (3). They are generally prepared by the evaporation of a solution containing the complexing salts. 

Stannous Oxide. Stannous oxide, SnO ((tin(II) oxide), mol wt 134.70, sp gr 6.5) is a stable, blue-black, crystalline product that decomposes at above 385°C. It is insoluble in water or methanol, but is readily soluble in acids and concentrated alkaHes. It is generally prepared from the precipitation of a stannous oxide hydrate from a solution of stannous chloride with alkaH. Treatment at controUed pH in water near the boiling point converts the hydrate to the oxide. Stannous oxide reacts readily with organic acids and mineral acids, which accounts and for its primary use as an intermediate in the manufacture of other tin compounds. Minor uses of stannous oxide are in the preparation of gold—tin and copper—tin mby glass. 

Prepa.ra.tlon, Triorganotin chlorides of the general formula R.SnX are the basic starting materials for other triorganotins. They are generally prepared by Kocheshkov redistribution from the cmde tetraorganotin ... 

Organolithium compounds can readily be prepared from metallic Li and this is one of the major uses of the metal. Because of the great reactivity both of the reactants and the products, air and moisture must be rigorously excluded by use of an inert atmosphere. Lithium can be reacted directly with alkyl halides in light petroleum, cyclohexane, benzene or ether, the chlorides generally being preferred ... 

A detailed discussion of individual halides is given under the chemistry of each particular element. This section deals with more general aspects of the halides as a class of compound and will consider, in turn, general preparative routes, structure and bonding. For reasons outlined on p. 805, fluorides tend to differ from the other halides either in their method of synthesis, their structure or their bond-type. For example, the fluoride ion is the smallest and least polarizable of all anions and fluorides frequently adopt 3D ionic structures typical of oxides. By contrast, chlorides, bromides and iodides are larger and more polarizable and frequently adopt mutually similar layer-lattices or chain structures (cf. sulfides). Numerous examples of this dichotomy can be found in other chapters and in several general references.Because of this it is convenient to discuss fluorides as a group first, and then the other halides. 

Deposition temperature rangeis 1000-1250°C and best deposits are obtained at low pressure (< 20 T orr). This reaction usually gives a more ductileandpurermaterialthandoesReaction(l)althoughhighertempera-ture is necessary. The chloride is generally prepared in situ by direct chlorination by heating the metal at 500-600°C (see Ch. 4).Pi... 

This reaction, parallel with 10-77, is the standard method for the preparation of sulfonyl halides. Also used are PCI3 and SOCI2, and sulfonic acid salts can also serve as substrates. Sulfonyl bromides and iodides have been prepared from sulfonyl hydrazides (ArS02NHNH2, themselves prepared by 10-126) by treatment with bromine or iodine.Sulfonyl fluorides are generally prepared from the chlorides, by halogen exchange. 

General preparative procedures for the preparation of A -alkyl phos-phoramidic dichlorides (10) and A TV -dialkyl phosphorodiamidic chlorides (11) from the appropriate amine and phosphoryl chloride have been described. With weakly basic amines, pyrophosphoryl chloride was... 

These precursors are generally prepared by alkane elimination (Equation (7a)) or—especially useful with bulkier substituents—the coupling of metal chlorides with lithium pnictides or silyl arsines (Equation (7b)) or salt elimination or silyl halide elimination reactions (Equation (7c)) ... 

Alkylidene sulfenes (75), generally prepared by the dehydrohalogenation of alkylsulfonyl chlorides, add readily to electron-rich multiple bonds. For example, with enamines, the thietane dioxide (e.g., 76) is formed diazoalkanes yield thiirane dioxides (episulfones) and imines (Schiff bases) afford 1,2-thiazetidine 1,1-dioxides. There are available numerous reviews of sulfenes, including cycloaddition reactions.102... 

These materials, generally prepared from the corresponding Grignard reagents by the addition of cadmium chloride, provide a milder reagent system than the Grignard that allows selectivity in reaction with phosphorus trichloride (Equation 4.21).34-43-63... 

Benzenedlazonlum chloride is prepared by the reaction of anUme with nitrous acid at 273-278K. Nitrous acid is produced In the reaction mixture by the reaction of sodium nitrite with hydrochloric acid. The conversion of prlmaiy aromatic amines into diazonium salts is known as diazotisation. Due to its Instability, the diazonium salt Is not generally stored and is used immediately after its preparation. 

The in situ generation of an afkyllithium reagent, from an alkyl chloride 13 and lithium in the presence of a catalytic amonnt of naphthalene (10%), and its reaction with carboxylic acids 14 allowed a general preparation of ketones 15 in a one-pot procednre (Scheme 6) °. 

The chiral dimethyl derivatives RR)-M and (SS)-84 of tetraethylene glycol have been employed (126) in the preparation of chiral macrocyclic polyether diesters such as (JU )-85 and (SS)S6. The reactions of the chiral diols with the appropriate diacid chlorides generally proceed (Scheme S) in good yield in warm benzene under high dilution conditions. 

Alkaline earth metal oxides are generally prepared by thermal decomposition of alkaline earth compounds, such as hydroxides, chlorides, sulfates, and carbonates. 

Oxetanones can be generally prepared by displacement processes on various /3-substituted carboxylic acids or by halolactonization of /3,y-unsaturated acids. A very general and reliable method consists of treatment of a /8-hydroxy acid with benzenesulfonyl chloride and pyridine at 0°C (equation 91). The yields of /3-lactones are usually in excess of 80% (79JOC356, 74JOC1322). An alternative method involves cyclization of the benzenethiol ester of a /3-hydroxy carboxylic acid by means of mercury(II) methanesulfonate in acetonitrile (equation 92). The yields were excellent in the two cases reported (76JA7874). 

Dithiocoumarins (50) are generally prepared by treatment of thiocoumarins with phosphorus pentasulfide, isolation being best effected by formation of a mercury complex by addition of mercurous chloride, followed by decomposition of this complex with sodium sulfide. An alternative ring-closure approach involves heating o-allylphenols (49) with sulfur in... 

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