Compounds with Halogen

It is possible to introduce sulfonic acid groups by alternative methods, but these ate Htde used in the dyes industry. However, one worth mentioning is sulfitation, because it provides an example of the introduction of a sulfonic acid group by nucleophilic substitution. The process involves treating an active halogen compound with sodium sulfite. This reaction is used in the purification of m-dinitrohen7ene. 

A new route to optically active amino-acids has been achieved by treatment of halogen compounds with Fe° or Ni° diastereoisomeric complexes of a-methylbenzyliminoglyoxylic acid ethyl ester. ... 

Avoidance or ban of unsafe techniques in the laboratory, e.g., oral suction of chemicals in pipettes, sucking of halogenated compounds with a water-jet pump because of effluent contamination. 

Reactions at o -Position. Many studies have been concerned with the reactions of alkyl halides with cyanide in the presence of various metal ions, and with the direct alkylation of cyanide complexes. The classic synthesis of isonitriles was accomplished by the use of silver cyanide, whereas the corresponding reaction of organic halogen compounds with alkali cyanides yields nitriles (Equations 40 and 41) (34,36). 

Halogen Compounds.—Practically all of the elements unite with chlorine, bromine, and iodine to form the corresponding halogen compounds. With the metals, well-defined solid salts are formed, save in cases in which the metal has a high valence and is a metallo-acid... 

Several commercially important photochemical processes involve the reaction of a halogenated compound with an organic substrate, and although it is the non-organic component that is excited, it is appropriate to describe them in this section. 

The more detailed conclusions that can be drawn from the studies of halogen compounds with benzene (Figures 7-9) are ... 

Reaction XLIV. (b) Condensation of Alkyl and Aryl Halogen Compounds with the Sodio- and other Metallo-derivatives of Ethyl Aceto-acetate and its Homolognes. (A., 186, 214 201, 143 213, 143.)—Like malonic ester, acetoacetic ester contains two 1 3-carbonyl groups with a methylene group in position 2. It is only to be expected then that it yields with metallic sodium or sodium alcoholate sodio-derivatives from which mono- and di-, alkyl and aryl homologues can be obtained by treatment with a suitable halide, including halogen esters. Acetoacetic acid... 

The degradation of many other halogenated compounds with Ti02 photocatalysis has been studied [112,122,144-148], as has the degradation of a number of other model compounds including carboxylic acids [110,130,149-151]. Other... 

B. Carbon-Halogen Compounds with Electronegative Substituents (EWG-C-X)... 

Carbenes are also formed by reactions of halogenated compounds with bases. If a carbon atom has bonds to at least one hydrogen and to enough halogen atoms to make the hydrogen slightly acidic, it may be possible to form a carbene. For example, bro-moform (CHBr3) reacts with a 50% aqueous solution of potassium hydroxide to form dibromocarbene. 

Bases are added frequently as promoters in catalytic dehalogenations to neutralize the liberated halogen acid that may inhibit the action of catalyst.196 Denton et al. studied the effects of added potassium acetate to the rates of hydrogenolysis of various halogen compounds with a Pd-C as catalyst in methanol (Table 13.8).196... 

The alkyl ethers of phenols, naphthols and hydroxyanthraquinones can be prepared, in many cases, by treatment of the halogen compounds with alcoholates at high temperature under pressure (e.g., anisole, page 97). Of course, the phenols themselves can be etherified (cf., page 148), and the cheaper method is used in each case. The dialkyl sulfates serve as active alkylating reagents in certain instances, as in the preparation of Caledon jade green (dimethoxydibenzanthrone). 

Direct Reaction of Organic Halogen Compounds with the Metal... 

A few nitro compounds have been obtained in good yields by the interaction of reactive halogen compounds with aci-nitro alkanes. The reaction is usually complicated in that both C- and 0-alkylation occurs. If the stability of the aci form of the nitro compound is high, then the tendency is toward alkylation on carbon rather than on oxygen. An example is the condensation of p-nitrobenzyl chloride with the sodium salt of nitro-ethane to give an 83% yield of 1-p-nitrobenzylnitroethane, P-OjNC.H CHjCHCNOjXIHj. ... 

Reactions of halogen compounds with nitric oxide and carbon monoxide... 

The question also arises how far the comparison may be extended to reactions which are not ionic. In the first instance we can only say that reactions must at least exist which are related to the polar nature of the linkage, e.g. the hydrolysis of halogen compounds or esters, but not (as one might expect) the reduction of halogen compounds with hydrogen. 

IV. Chalcogen-Halogen Compounds with Homonuclear Chalcogen-Chalcogen Bonding... 

Mainly halogenated compounds with enough halogens to activate the hydrogens CHCU, G2HGlj, etc. and possibly G2H2 protons... 

Poly [p-(cc-lithiumalkyl)styrenes] with n = 1 to 4 were synthesized by the reaction of the corresponding halogen compounds with n-butyllithium. The application of these organometallic polymers as metallatir agents to halogen-containing... 

Considerably less work has been done on the kinetic aspects of the radiolysis of fluorine compounds than on other halogen compounds. With °Co y-radiation, perfluoromethane produces perfluoroethane , and perfluoroethane produces (refs. 351, 352) a mixture of perfluoromethane, -propane, -butane, -cyclopropane, and -acetylene. Similar radiolysis studies on perfluorocyclobutane , perfluoro-cyclohexane and other perfluoro-compounds show that the dominant process is one of rupture of the carbon-carbon bond with the formation of a variety of perfluoro-compounds as products. 

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