Group fluorine iodine

The halogens are a family of elements appearing on the right side of the periodic table, in the column just before the inert gases. The elements in this group—fluorine, chlorine, bromine, iodine, and astatine—show some remarkable similarities and some interesting trends in chemical behavior. The similarities are expected since the... 

Sec also Bromine Carbon Chlorine Chlorinated Organics Fluorine Halogen Group anil Iodine. 

Like Paneth, he believed that the elements are essentially unobservable. He also believed that the periodic system should classify the unobservable basic substances in preference to simple substances. For example, the elements in the halogen group (fluorine, chlorine, bromine, and iodine) are rather different if we focus on the isolable simple substances that are gaseous, liquid, and solid, respectively. The similarity between the members of the group are more noticeable when it comes to the compounds of each one with sodium, for example, which are all crystalline white powders. The point is that in these compounds—fluorine, chlorine, bromine, and iodine—are not... 

Bollard and Butler (1966) in their discussion of functional elements include several others in addition to the above four. They state that fluorine, iodine, and selenium fall in this class for in some plant species they are metabolized, forming definite organic compounds. Bromine, rubidium, and strontium are also placed in this class because they exert a sparing effect on the utilization of chloride, potassium and calcium. Cobalt may perform that same function. They state further that our knowledge of the beneficial effects produced by aluminum, beryllium, and barium are not as yet adequate to justify including these in the group of functional elements. Further research will probably add other elements to this group. 

Any of a group of five chemically related nonmetallic elements chlorine, bromine, fluorine, iodine, and astatine. Chlorine compounds are used as EP additives in certain lubricating oils, and as constituents of certain petrochemicals (e.g., vinyl chloride, chlorinated waxes). Chlorine and fluorine compounds are also used in some synthetic lubricants. 

The most widely used reactions are those of electrophilic substitution, and under controlled conditions a maximum of three substituting groups, e.g. -NO2 (in the 1,3,5 positions) can be introduced by a nitric acid/sul-phuric acid mixture. Hot cone, sulphuric acid gives sulphonalion whilst halogens and a Lewis acid catalyst allow, e.g., chlorination or brom-ination. Other methods are required for introducing fluorine and iodine atoms. Benzene undergoes the Friedel-Crafts reaction. ... 

The order of alkyl halide reactivity in nucleophilic substitutions is the same as their order m eliminations Iodine has the weakest bond to carbon and iodide is the best leaving group Alkyl iodides are several times more reactive than alkyl bromides and from 50 to 100 times more reactive than alkyl chlorides Fluorine has the strongest bond to car bon and fluonde is the poorest leaving group Alkyl fluorides are rarely used as sub states m nucleophilic substitution because they are several thousand times less reactive than alkyl chlorides... 

Fluorination and iodination reactions are used relatively littie in dye synthesis. Fluorinated species include the trifluoromethyl group, which can be obtained from the trichi oromethyl group by the action of hydrogen fluoride or antimony pentafluoride, and various fluorotria2iQyl and pyrimidyl reactive systems for reactive dyes, eg, Cibacron F dyes. 

A nitro group in the artho or para position to fluonne is known to enhance its replacement by hydroxyl [II, 12] Bromine and iodine are much less prone to hydrolysis under similar conditions The effect is much less pronounced with the meta nitro derivative (equation 11) With o-nitro-p-fluoroaniline, it is the amino group ortho to the nitro group, rather than meia fluorine, that is replaced by hydroxyl (equation 12)... 

Chlorination is cariied out in a manner similar- to bromination and provides a ready route to chlorobenzene and related ar-yl chlorides. Fluorination and iodination of benzene and other arenes are rarely perfor-med. Fluorine is so reactive that its reaction with benzene is difficult to control. Iodination is very slow and has an unfavorable equilibrium constant. Syntheses of aryl fluorides and aryl iodides are nor-mally cariied out by way of functional group transformations of arylffluines these reactions will be described in Chapter 22. 

Polarizability (Section 4.6) A measure of the ease of distortion of the electric field associated with an atom or a group. A fluorine atom in a molecule, for example, holds its electrons tightly and is very nonpolarizable. Iodine is very polarizable. 

Perhaps the most reactive compound of the group is BiFs- It reacts extremely vigorously with H2O to form O3, OF2 and a voluminous brown precipitate which is probably a hydrated bismuth(V) oxide fluoride. At room temperature BiFs reacts vigorously with iodine or sulfur above 50° it converts paraffin oil to fluorocarbons at 150° it fluorinates UF4 to UF and at 180° it converts Brs to BrFs and BrFs, and CI2 to CIF. 

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