Molecular chlorine

An earlier report51 that phenanthridone is brominated at C-2 on treatment with bromine in acetic acid has been confirmed291 chlorination (molecular chlorine) and iodination (iodine-iodate) in acetic acid give the corresponding 2-halogeno compounds in excellent yield.291 The bromination of 2-acetamidophenanthridone has also been described, although the orientation was not established with certainty.291... 

Chlorine-containing Polymers. Polymers containing one chlorine atom in various environments (other sustituents) were studied by XPS poly(vinyl chloride) PVC, poly(chlorotrifluoro-ethylene) PCTFE, an (ethylene-chlorotrifluoroethylene) copolymer, and poly(epichlorohydrine) PEPI, were chosen because besides carbon atoms they contain chlorine in presence of hydrogen, fluorine, and oxygen atoms. The valence band spectra of these compounds (see Figure 9) show that features can be easily and unambiguously assigned to a contribution from the chlorine molecular orbitals. 

The mono and dichlorobenzenes do not show parent negative ions at 373 K or 523 K. This does not imply that the electron affinity is negative, but rather that other processes occur. Both dissociative and nondissociative capture are observed for the tri and tetrachlorobenzenes. For the penta and hexachlorobenzenes no dissociative attachment is observed. For the biphenyls with two chlorines ion molecule reactions predominate. With three chlorines, two on one ring and the third on the other ring, molecular ions are observed at 373 K. With four or more chlorines molecular ions are observed at both high and low temperatures, and dissociative electron... 

Research has shown that the presence of catalytic surfaces and particles increases the yields and rates of formation of PCDD/F in combustion systems over the reaction temperature range of 200-600 °C. Transition metals such as copper can increase the rate of chlorination, molecular growth, and aromatic condensation reactions to form PCDD/F. Also, reactive species can attack a carbon matrix to chlorinate and fragment the carbon lattice-forming PCDD/F as well as other chlorinated hydrocarbons. Although research to date has focused on surface-me-... 

Chlorine dissolves in water to form chlorine water. At 10°C about 10 g 1 can be dissolved, and the above reactions (3.78) take place. The solution of chlorine has both chlorinating and oxidizing effects. In hydrochemistry the term active chlorine denotes all forms of chlorine which oxidize iodides into iodine in acid media. It is necessary to differentiate between free active chlorine (molecular chlorine, hypochlorites, chlorine dioxide) and bonded active chlorine (active chlorine in chloramines). In water, chloramines are slowly hydrolysed into hypochlorites, and they are weaker oxidizing agents than chlorine. The oxidation of Fe(II) and Mn(II) by chloramines is not very effective. 

Aroclor series, the first two digits define the type of molecular structure and the last two are the weight percent of chlorine. Molecular structural types are 12 for PCBs, 25 and 44 for blends of PCBs and PCTss (polychlorinated triphenyls), and 54 for PCTs. Thus, Aroclor 1221 would indicate a composition of PCBs with biphenyl structure having 21% chlorine by weight. The most common Aro-clors are 1221, 1232, 1242, 1248, 1254, 1260, and 1262. 

Common name Chlorine Molecular formula CI2 Atomic weight 35.453 Molecular weight 70.906 CAS number 7782-50-5 UN number 1017 RTECS number F02100000 Labels Corrosive gas Specific hazards Corrosive... 

Variational Transition State Theory With Least-Action Tunneling Calculations for the Kinetic Isotope Effects in the Atomic Chlorine + Molecular Hydrogen Reaction Tests of Extended-LEPS, Information-Theoretic, and Diatomics-in-Molecules Potential Energy Surfaces. 

A second family is based on isobutene polymers (PIB) having molecular weights from 600 to 2000 that are equally important raw materials for detergent additives. So as to render them reactive with the hydrophilic part, they can be chlorinated or condensed with the maleic anhydride. A third way is based on the utilization of polypropylphenols of molecular weights between 600 and 3000. 

Derivatives of polyisobutylene (6. in Figure 9.1) offer the advantage of control over the molecular weight of the polyisobutylene obtained by cationic polymerization of isobutylene. Condensation on maleic anhydride can be done directly either by thermal activation ( ene-synthesis reaction) (2.1), or by chlorinated polyisobutylene intermediates (2.2). The condensation of the PIBSA on polyethylene polyamines leads to succinimides. Note that one can obtain mono- or disuccinimides. The mono-succinimides are used as... 

Chang J P, Arnold J C, Zau G C H, Shin H-S and Sawin H H 1997 Kinetic study of low energy ion-enhanced plasma etching of polysilicon with atomic/molecular chlorine J. Vac. Sc/. Technol. A 15 1853-63... 

Barone M E and Graves D B 1995 Molecular dynamics simulations of direct reactive ion etching of silicon by fluorine and chlorine J. Appi. Phys. 78 6604-15... 

The range of systems that have been studied by force field methods is extremely varied. Some force fields liave been developed to study just one atomic or molecular sp>ecies under a wider range of conditions. For example, the chlorine model of Rodger, Stone and TUdesley [Rodger et al 1988] can be used to study the solid, liquid and gaseous phases. This is an anisotropic site model, in which the interaction between a pair of sites on two molecules dep>ends not only upon the separation between the sites (as in an isotropic model such as the Lennard-Jones model) but also upon the orientation of the site-site vector with resp>ect to the bond vectors of the two molecules. The model includes an electrostatic component which contciins dipwle-dipole, dipole-quadrupole and quadrupole-quadrupole terms, and the van der Waals contribution is modelled using a Buckingham-like function. 

Rodger P M, A J Stone and D J Tildesley 1988. The Intermolecular Potential of Chlorine. A Three Phase Study. Molecular Physics 63 173-188. 

His data suggested values for y of — 12 and — 6 kcal mol for molecular chlorination and nitration respectively, indicating that the transition states in nitration resemble the reactants more than do the transition states in chlorination. 

The high regioselectivity ( stereoelectronic control ) in the ring cleavage by chlorination of sulfur was anticipated. It had been found before that in corresponding bicyclic systems such as in the scheme below oxidation of the sulfur atom always led to the undesired cleavage of the S—Cg bond. This was rationalized through the observation on molecular models that... 

Structural drawings (molecular models too) can be deceiving For example the chlonne atoms in 1 2 dichlorocyclohexane seem much closer to each other in a drawing of the trans stereoisomer than in the cis Make a molecular model of each and measure the distance between the chlorines What do you find" ... 

Step 3 Reaction of methyl radical with molecular chlorine... 

Among the isomenc alkanes of molecular formula C5H12 identify the one that on photo chemical chlorination yields... 

Unlike the case of benzene in which ionization involves loss of a tt electron from the ring electron impact induced ionization of chlorobenzene involves loss of an elec tron from an unshared pair of chlorine The molecular ion then fragments by carbon-chlorine bond cleavage... 

Chlorination of 2 butanone yields two isomeric products each ) having the molecular formula C4H7CIO Identify these two compounds I... 

Because carbon is sp hybridized m chlorobenzene it is more electronegative than the sp hybridized carbon of chlorocyclohexane Consequently the withdrawal of electron density away from carbon by chlorine is less pronounced m aryl halides than m alkyl halides and the molecular dipole moment is smaller... 

In a process similar to that described in the previous item, the stored data can be used to identify not just a series of compounds but specific ones. For example, any compound containing a chlorine atom is obvious from its mass spectrum, since natural chlorine occurs as two isotopes, Cl and Cl, in a ratio of. 3 1. Thus its mass spectrum will have two molecular ions separated by two mass units (35 -i- 2 = 37) in an abundance ratio of 3 1. It becomes a trivial exercise for the computer to print out only those scans in which two ions are found separated by two mass units in the abundance ratio of 3 1 (Figure 36.10). This selection of only certain ion masses is called selected ion recording (SIR) or, sometimes, selected ion monitoring (SIM, an unfortunate... 

Naturally occurring isotopes of any element are present in unequal amounts. For example, chlorine exists in two isotopic forms, one with 17 protons and 18 neutrons ( Cl) and the other with 17 protons and 20 neutrons ( Cl). The isotopes are not radioactive, and they occur, respectively, in a ratio of nearly 3 1. In a mass spectrum, any compound containing one chlorine atom will have two different molecular masses (m/z values). For example, methyl chloride (CH3CI) has masses of 15 (for the CH3) plus 35 (total = 50) for one isotope of chlorine and 15 plus 37 (total = 52) for the other isotope. Since the isotopes occur in the ratio of 3 1, molecular ions of methyl chloride will show two molecular-mass peaks at m/z values of 50 and 52, with the heights of the peaks in the ratio of 3 1 (Figure 46.4). 

This example can be used in reverse to show the usefulness of looking for such isotopes. Suppose there were an unknown sample that had two molecular ion peaks in the ratio of 3 1 that were two mass units apart then it could reasonably be deduced that it was highly likely the unknown contained chlorine. In this case, the isotope ratio has been used to identify a chlorine-containing compound. This use of mass spectrometry is widespread in general analysis of materials, and it... 

A diagrammatic illustration of the effect of an isotope pattern on a mass spectrum. The two naturally occurring isotopes of chlorine combine with a methyl group to give methyl chloride. Statistically, because their abundance ratio is 3 1, three Cl isotope atoms combine for each Cl atom. Thus, the ratio of the molecular ion peaks at m/z 50, 52 found for methyl chloride in its mass spectrum will also be in the ratio of 3 1. If nothing had been known about the structure of this compound, the appearance in its mass spectrum of two peaks at m/z 50, 52 (two mass units apart) in a ratio of 3 1 would immediately identify the compound as containing chlorine. 

For other elements that occur with major relative abundances of more than one isotope in the natural state, the isotope pattern becomes much more complex. For example, with chlorine and bromine, the presence of these elements is clearly apparent from the isotopes Cl and for chlorine and Br and Br for bromine. Figure 47.2a shows the molecular ion region for the compound chlorodecane. Now, there are new situations in that C, C, C1, and Cl isotopes all have probabilities of occurring together. Thus, there are molecular ion peaks for + Cl, C + Cl, + Cl, and so on. Even so, the isotopic ratio of 3 1 for Cl to Cl is very clear... 

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