Chlorine chemical reactivity

The reaction of an alcohol with a hydrogen halide is a substitution A halogen usually chlorine or bromine replaces a hydroxyl group as a substituent on carbon Calling the reaction a substitution tells us the relationship between the organic reactant and its prod uct but does not reveal the mechanism In developing a mechanistic picture for a par ticular reaction we combine some basic principles of chemical reactivity with experi mental observations to deduce the most likely sequence of steps... 

Chlorendic anhydride is the common name of the Diels-Alder adduct of maleic anhydride and hexachlorocyclopentadiene, 3,4,5,6,7,7-hexachloroendomethylene-l,2,3,6-tetrahydrophthahc anhydride (HET). The resultant resins from HET contribute to the flame retardancy of the alkyd coatings. HET gives a greater reaction rate than phthaUc anhydride, to the extent that at 204—210°C the reaction rate approximates that of phthaUc anhydride at a temperature of 238°C (8). However, the resins tend to develop darker color, particularly at high processing temperature. Tetrachlorophthahc anhydride [117-08-8] made by conventional chlorination of phthaUc anhydride, would also impart flame retardancy to its alkyds. However, it is appreciably less soluble in the usual processing solvents than is phthaUc anhydride, and is reported to be of appreciably lower chemical reactivity (8). 

Reactivities of several chlorinated solvents, including chloroform, with aluminum, iron, and 2inc in both dry and wet systems have been deterrnined, as have chemical reactivities in oxidation reactions and in reactions with amines (11). Unstabilized wet chloroform reacts completely with aluminum and attacks zinc at a rate of >250 //m/yr and iron at <250 //m/yr. The dry, uiiinhibited solvent attacks aluminum and zinc at a rate of 250 )J.m/yr and iron at 25 ]lni / yr. 

Chemical Reactivity - Reactivity with Water Reacts violently with water forming hydrogen chloride (hydrochloric acid), chlorine gases, and chromic acid Reactivity with Common Materials Causes severe corrosion of common metals Stability During Transport Stable Neutralizing Agents for Acids and Caustics Flood with water and rinse with sodium bicarbonate Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

The lactam-lactim tautomerism of hydroxyquinazolines is reflected in their chemical reactivity. Thus they are chlorinated to 4-chloro-quinazolines (see Section VI,A), and both 0- and A-methylation have been observed. When a substituent is already present on a nitrogen atom, as in 3-methyl-4(3i7)quinazolinone, chlorination gives 4-chloroquinazoline with loss of the methyl group (see la). 2-... 

As we saw in Chapter 19, chlorine represents the other extreme in chemical reactivity. Its most obvious chemical characteristic is its ability to acquire electrons to form negative chloride ions, and, in the process, to oxidize some other substance. Since the tendency to lose or gain electrons is a result of the details of the electronic structure of the atom, let us try to explain the chemistry of the third-row elements on this basis. 

Of all the elements, fluorine is the most chemically reactive. It combines directly with other elements. Chlorine is slightly less reactive. Both are gases at room temperature which is an important advantage in delivery and metering. Because of their reactivity, they form halides readily, but also attack most materials which makes them difficult to handle and requires equipment designed with inert materials such as Monel or Teflon. Halogens are also toxic, fluorine more so than chlorine by an order of magnitude. 

Bonse G, Urban T, Reichert D, et al. 1975. Chemical reactivity, metabolic oxirane formation, and biological reactivity of chlorinated ethylenes in the isolated perfused rat liver preparation. Biochem Pharmacol 24 1829-1834. 

Lower chemical reactivity with non-target molecules is useful for another performance-related reason. Microorganisms prefer the protection and luxuriant environment in biofilms (the adherent microbial communities that cause detrimental surface-fouling effects in water cooling systems). Most (>99%) of the viable microorganisms in industrial systems are found in biofilms, not floating around freely in the bulk recirculating water. Compared to unstabilized chlorine or bromine, STABREX more effectively removes and disinfects biofilms as shown in Table 6. 

There is a marked difference in chemical reactivity between bridging and terminal hydrogens. Terminally bonded hydrogens readily react in a similar manner to that observed for mononuclear hydrides. Thus reactions with chlorinated hydrocarbons such as carbon tetrachloride yield the chloro cluster complexes and chloroform. In contrast, bridging hydrides are stable and may be studied in chlorinated sol-... 

Also other Type B and C series from Table II are consistent with the above elimination mechanisms. The dehydration rate of the alcohols ROH on an acid clay (series 16) increased with the calculated inductive effect of the group R. For the dehydrochlorination of polychloroethanes on basic catalysts (series 20), the rate could be correlated with a quantum-chemical reactivity index, namely the delocalizability of the hydrogen atoms by a nucleophilic attack similar indices for a radical or electrophilic attack on the chlorine atoms did not fit the data. The rates of alkylbenzene cracking on silica-alumina catalysts have been correlated with the enthalpies of formation of the corresponding alkylcarbonium ions (series 24). Similar correlations have been obtained for the dehydrosulfidation of alkanethiols and dialkyl sulfides on silica-alumina (series 36 and 37) in these cases, correlation by the Taft equation is also possible. The rate of cracking of 1,1-diarylethanes increased with the increasing basicity of the reactants (series 33). 

The double bond difference between the olefins and the paraffins is the quintessential difference between the petrochemicals and petroleum products— the petrochemicals industry depends much more on the chemical reactivity of the double-bonded molecules. While paraffins can be manipulated in refineries by separation or reshaping, olefins in a petrochemical plant are usually reacted with other organic compounds or another kind of atom or compound such as oxygen, chlorine, water, ammonia, or more of itself. The results are more complicated compounds useful in an increasing number of chemical applications. More on this in later chapters. 

Iodine has had limited application for disinfection of swimming pools [7] and small public water supplies [8]. One application in a reverse osmosis system has also been reported by Turby and Watkins [9]. Advantages of iodine are greater stability than chlorine, lower residual requirement, and diminished chemical reactivity toward dissolved organic compounds. 

Similarly, the chemical reactivity of these two chlorine oxyfluorides differs vastly whereas ClFsO is extremely reactive and cannot be handled even in a well-dried glass vacuum system, FCIO3 reacts only slowly with water. 

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