Chloro-substituted methanes

Figure 5. The four upper curves show the derivative of transmitted current in the chloro-substituted methanes. The vertical arrows indicate the experimental midpoints of the resonances. The vertical lines locate the theoretical anion energies and show the orbital symmetries. The theoretical energies are normalized to the experimental data only at the resonance in CHClt.3. Reproduced with permission from Ref. 43. Copyright 1982, American Institute of Physics.

Muller, R., Reichel, S., Dathe, C. Trifluorsilyl substituted methanes and chloro-methanes. Chem. Ber. 97, 1673 (1964). 

Molecular Structure and Vibrational IR Spectra of Fluoro, Chloro and Bromo-substituted Methanes, Silanes and Germanes An Ab Anitio Approach (J. S. Kwiatkowski J. Leszczynski)... 

Substituting a diird chlorine on the methane molecule results in the compound whose proper name is trichloromediane (tri- for three chloro- for chlorine and methane, the hydrocarbon s name for die one-carbon chain). It is more commonly known as chloroform. Its molecular formula is CHC13. Chlorofonn is a heavy, colorless, volatile liquid with a sweet taste and characteristic odor. It is classified as non-flammable, but it will bum if exposed to high temperatures for long periods of time. It is narcotic by inhalation and toxic in high concentrations. It is an insecticide and a fumigant and is very useful in the manufacture of refrigerants. 

A simple example of a substitution reaction is the formation of chloro-methane from methane and chlorine ... 

A series of monosubstituted acetonitriles were treated with disulfur dichloride at room temperature in dichloro-methane to afford 5-substituted-4-chloro-l,2,3-dithiazolium chlorides 179 <2005MI346> (Equation 49). Several of the dithiazolium chlorides 179 were converted into corresponding 4-substituted-3-chloro-l,2,5-thiadiazoles by treatment with aqueous ammonia. 

Acyclic 295 and cyclic 296 hemithioacetals have been shown as precursors of formyl-lithium intermediates13. For the preparation of the starting methoxy(phenylsulfanyl) methane 295466 two main procedures can be used (a) nucleophilic substitution of chloro-methyl methyl ether with thiophenol under basic conditions467,468 and (b) boron trifluoride etherate-catalyzed condensation of thiophenol and dimethoxymethane166. 1,3-Oxathiane and its derivatives can be prepared by acetalization of the corresponding carbonyl compound with 3-mercaptopropanol. 

Ttie second large-scale use of methane is its halogenation [I], where chlorine and fluorine are the most important halogens for methane substitution. Chloro-methanes aie formed by thermal chlorination or catalyzed uxychlorination of methane. Monochlorination is controlled by using a ten-fold excess of methane. 

D-Berine methyl ester is converted into the IJ-triphenylmethyl derivative which, when heated in the presence of methane sulphonyl chloride, yielded the substituted ethylene-amine (2). Reaction of (2) with hydroxyl-amine and sodium methoxide gives the corresponding hydroxamic acid (3) This product is converted, by the action of hydrochloric acid, into D-a amiso-3-chloro-H-hydroxypropionamide (k), which undergoes cyclization to D-cycloserine (5) when treated with a strongly basic ion exchange resin. 

Enamines derived from cyclohexanone and and a-tetralones react with chloro-(phenyl)carbene [generated from dichloro(phenyl)methane and potassium tert-butoxide] to give either 1-chloro-l-phenyl-substituted cyclopropanes, or other products.The type of products formed depends on the structure of the amine moiety in the starting enamines (Table 7). 

Notice that each step in the process involves replacement of a C—H bond by a C—Cl bond. Thaf is, a chlorine afom substitutes for a hydrogen atom. The names of the products of fhese reactions use the term chloro for fhe chlorine substituents with a prefix that gives the number of chlorine atoms present di- for two, tri- for three, and tetra- for four. No number is used to describe the chlorine positions in this case, because methane has only one carbon atom. Note that the products of fhe last two reactions have two names, the systematic name and the common name in parentheses. 

There is evidence of analogous hyperconjugative interaction in F-substituted compounds. In particular, the v(C-H) for methyl fluoride is 16 cm" red-shifted relative to methane (2976 vs. 2992 cm" ). Because hybridization effects imposed by Bent s rule should increase s-character in the C-H bonds and lead to the blue-shift, the experimental red-shift observation indicates the importance of np->-o C-H interactions. Additional fluorine substituents remove most of the red-shift (v(C-H) for CH F and CHFj are 2984 vs. 2990cm" respectively) suggesting the increasing importance of rehybridization (progressive s-character increase in the C-H bond(s)) and, possibly, the importance of Up o C-F interactions that partially neutralize the donor capacity of the fluorine lone pairs. Small blue-shifts are observed for the chloro- and bromoderivatives of methane. 

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