The Rise of Trichlorides Enabling an Improved Chlorine Technology

Chlorine plays a central role for the industrial production of numerous materials with global relevance. More recently, polychlorides have been evolved from an area of academic interest to a research topic with enormous industrial potential. In this minireview, the value of trichlorides for chlorine storage and chlorination reactions are outlined. Particularly, the inexpensive ionic liquid [NEt₃Me][Cl₃] shows a similar and sometimes even advantageous reactivity compared to chlorine gas, while offering a superior safety profile. Used as a chlorine storage, [NEt₃Me][Cl₃] could help to overcome the current limitations of storing and transporting chlorine in larger quantities. Thus, trichlorides could become a key technique for the flexibilization of the chlorine production enabling an exploitation of renewable, yet fluctuating, electrical energy. As the loaded storage, [NEt₃Me][Cl₃], is a proven chlorination reagent, it could directly be employed for downstream processes, paving the path to a more practical and safer chlorine industry.     

Determination of low chlorine concentrations in air using semiconductor chemical sensors

Comparative studies of electophysical gas-sensitive properties of semiconductor metal oxides (NiO, WO₃, and In₂O₃) in detecting trace concentrations of chlorine in air at 250–300°C were performed. WO₃ and In₂O₃ film sensors were found to have the best sensitivity, selectivity, and stability. However, WO₃ films are characterized by a longer relaxation time (3 min) compared to In₂O₃ films, for which it is no longer than 30 s. The kinetic and steady-state relative conductivity values of In₂O₃ films as functions of the chlorine concentration in air fall on the same curve in the range 0.01–0.7 ppm. This suggests that the concentration of chlorine in air can be determined from the initial rates of the variation of the relative conductivity of films, which significantly decreases the time of analysis (from 40 to 5 s at a sensor working temperature of 300°C). Changes in air humidity in the range from 40 to 80% have no effect on the initial rates of the variation of the relative conductivity of In₂O₃ films under kinetic conditions. The mechanism of the variation of In₂O₃ film conductivity in detecting chlorine in air was discussed.     

Effect of structural features of molecules (Cl<Subscript>3</Subscript>PNZ)<Subscript>2</Subscript> (Z = CH<Subscript>3</Subscript> and CH<Subscript>2</Subscript>CH<Subscript>2</Subscript>Cl) on the position exchange of chlorine atoms in the P-Cl fragments

Based on the analysis of structural parameters of molecules (Cl₃PNCH₃)₂ (I) and (Cl₃PNCH₂CH₂Cl)₂ (II) by the quantum-chemical nonempirical calculations the following was revealed. The structure of I and II dimers has geometric features, which have a decisive influence on the degree of inhibition of positional exchange of the chlorine atoms in the P-Cl fragments known for the chlorine derivatives of pentacoordinated phosphorus atom. The obstacles to this dynamic process in the mentioned intramolecular dimers is shown to result from the spatial nonvalent interactions due to the short contacts of the chlorine and hydrogen atoms.     

Olefin Polymerization and Copolymerization with Alkylaluminum-lnitiator Systems. VII. Initiation by Electrophilic Halogens

Abstract

The discovery of initiation of cat ionic polymerization of isobutylene and styrene by electrophilic chlorine generated by the reaction of chlorine and trimethylaluminum in the temperature range -40 to -100° is reported. Bromine and trimethylaluminum is a very poor initiating system, and iodine and trimethylaluminum does not initiate the polymerization of either isobutylene or styrene. Polymerization of isobutylene initiated by chlorine and trimethylaluminum shows a linear plot of log M_v vs 1/T with an overall E_DPof ～1.9 kcal, mole. The molecular weights (M_w) of polystyrene obtained with the Cl₂/Me₃Al system appear to be the highest ever reported for cationic polymerization of this monomer under comparable conditions. The mechanism of initiation has been investigated by model experiments: The reaction between Cl₂/ Me₃Al and 2,2,4-trimethyl-l-pentene gave three chlorinated products (2-chloromechyl-4,4-dimethyl-l-pentene, 1-chloro-2,4,4-trimethyl-1-pentene, and 2-chioromethyl-2,4,4-trimethyl-pentane). The position of chlorine in these compounds indicate initiation by electrophilic chlorine, Cl. Some preliminary results obtained using diethylaluminum chloride-halogens as coinitiator-initiator systems are also described.     

Reaction of chlorine fluorosulfate with 1-trifluoromethoxy-1,2-dichlorotrifluoroethane and 1,2-dichlorohexafluoropropane

Conclusions The reactivity of chlorine fluorosulfate increases with increasing acidity of the medium. In HSO₃F/SbF₅, chlorine fluorosulfate under mild conditions replaces the terminal chlorine atom in 1,2-dichlorohexafluoropropane and both chlorine atoms in 1-trifluoromethoxy-1,2-dichlorotrifluoroethane by fluorosulfate groups.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1669–1672, July, 1985.     

Measurement of the Rate Constant of a Reaction of Chlorine Atoms with CH<Subscript>3</Subscript>Br in a Temperature Range of 298–358 K Using the Resonance Fluorescence of Chlorine Atoms

The rate constant of the reaction of chlorine atoms with CH₃Br was measured in a temperature range of 298–358 K using the resonance fluorescence of chlorine atoms. The possible role of this reaction in atmospheric chemistry and fire extinguishing was discussed. It was found that this reaction is homogeneous in contrast to the previously studied reaction of chlorine atoms with CH₃I, with occurs at the reactor surface.     

Quantum mechanical studies of isomeric and conformeric structures of methyl‐chloro‐peroxide

Ab initio quantum mechanical studies are carried out for the isomeric structures and the torsional potential of methyl‐chloro‐peroxide. These species are important intermediates in the atmospheric reactions of methyl, methoxy, and methylperoxy radicals with chlorine dioxide, chlorine monoxide, and atomic chlorine, respectively. The calculations indicate that the peroxide form, CH₃OOCl, with a skew geometry for C, O, O, and Cl atoms, is the lowest minimum energy structure followed by CH₃OClO. The CH₃ClO₂ adduct is found to be much higher in energy. The calculated isomerization barriers are found to be relatively high to permit possible interconversion pathways. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

Measurements of the apparent rate constant for the reaction of iodine monoxide with chlorine monoxide to form iodine atoms

An apparatus for measuring the resonance fluorescence signals of iodine and chlorine atoms is constructed to study iodine monoxide reaction with chlorine monoxide. A technique using the reaction of chlorine atoms with C₂H₆ is developed to calibrate the sensitivity of the apparatus to chlorine atoms. The apparent rate constants for the reaction between 10^• and CIO^• radicals producing iodine atoms was measured at 295 K k_app = (2.62 ± 0.57) x 10-^-11 cm³ molecule^-1 s^-1.     

Hydroalumination of a Chlorotrialkynylsilane: Spontaneous Stepwise 1,3‐Dyotropic Rearrangement via an Intermediate Silyl Cation

A new functionalised alkynylsilane, Cl‐Si(C?C‐CMe₃)₃ ( 3 ), was obtained by a facile multistep synthesis. Treatment of 3 with equimolar quantities of the hydrides H‐M(CMe₃)₂ (M=Al, Ga) gave the mixed alkenyl‐di(alkynyl)silanes, in which the chlorine atom adopts a bridging position between the aluminium and silicon atoms. Dual hydrogallation of 3 resulted in the formation of a di(alkenyl)‐alkynylsilane containing two gallium atoms, one of which is coordinated to the chlorine atom, and the second is bonded to the α‐carbon atom of the remaining alkynyl group. A tert‐butylsilane was unexpectedly formed by a unique 1,3‐dyotropic chlorine–tert‐butyl exchange for the corresponding dialuminium compound. One aluminium atom is bonded to a tert‐butyl group, a terminal chlorine atom and the α‐carbon atom of the ethynyl moiety; the second is coordinatively unsaturated, with two terminal tert‐butyl substituents. High‐level quantum‐chemical calculations favour a stepwise dyotropic rearrangement with an intermediate cationic silicon species over a simultaneous tert‐butyl–chlorine migration via a five‐coordinate silicon atom in the transition state.     

Investigations of oxidizing additives in flash combustion of organic chlorine compounds

Summary The suitability of V₂O₅ and Co₃O₄ deposited on porous silica as the combustion aids for flash combustion of organic chlorine compounds has been studied. The chlorine recovery as a function of sweep-out time with a stream of dry or moist oxygen was determined. Quantitative removal of chlorine from a tube inca. 10 min can be achieved only with a stream of moist oxygen. Combustion in a stream of moist oxygen in the presence of Co₃O₄ precludes final gravimetric determination of chlorine by binding it on metallic silver, because the capacity of the silver for reaction with chlorine in the form of HCl rapidly decreases, falling to about 30% of the initial value after only 5 determinations. Iodogravimetric determination of the chlorine yields correct results and allows simultaneous determination of carbon, for samples up to 45 mg.

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Untersuchungen über Oxydationszusätze bei der Entflammungsmineralisation organischer Chlorverbindungen

Zusammenfassung Die Eignung von V₂O₅ und Co₃O₄ als Zusatzmittel auf porösem Kiesel zur Förderung der Schnellverbrennung von organischen Chlorverbindungen wurde untersucht. Die Chlorausbeute als Funktion der Ausspülzeit mit trockenem oder feuchtem Sauerstoff wurde bestimmt. Die quantitative Entfernung des Chlors aus dem Verbrennungsrohr in ca. 10 min gelingt nur mit einem Strom feuchten Sauerstoffs. Die Verbrennung in feuchtem Sauerstoff bei Gegenwart von Co₃O₄ schließt die gravimetrische Chlorbestimmung durch Bindung an metallisches Silber aus, da dessen Reaktionskapazität mit Chlor in der Form von HCl rasch abfällt, so daß sie bereits nach fünf Bestimmungen nur mehr etwa 30% beträgt. Die jodgravimetrische Bestimmung des Chlors gibt korrekte Ergebnisse und erlaubt bei Einwaagen bis zu 45 mg die gleichzeitige Bestimmung des Kohlenstoffs.

     

Esr spectral determination of the relative rate constants for the abstraction of halogen by M(CO)4L species (L=CO,PPh3; M=Cr,Mo, W)

Conclusion The rate constants for the abstraction of bromine from PhCH₂Br and of chlorine from CCl₄ by M(CO)₅ and M(CO)₄PPh₃ species (M=Cr, Mo, and W) are two orders of magnitude greater than the rate constants for chlorine abstraction from PhCH₂Cl; the difference in the rates of chlorine abstraction from CCl₄ and C₂Cl₆ by these species is within an order of magnitude.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1149–1151, May, 1987.     

High Power- and Energy-Density Supercapacitors through the Chlorine Respiration Mechanism

Supercapacitor represents an important electrical energy storage technology with high-power performance and superior cyclability. However, currently commercialized supercapacitors still suffer limited energy densities. Here we report an unprecedentedly respiring supercapacitor with chlorine gas iteratively re-inspires in porous carbon materials, that improves the energy density by orders of magnitude. Both electrochemical results and theoretical calculations show that porous carbon with pore size around 3 nm delivers the best chlorine evolution and adsorption performance. The respiring supercapacitor with multi-wall carbon nanotube as the cathode and NaTi₂(PO₄)₃ as the anode can store specific energy of 33 Wh kg⁻¹ with negligible capacity loss over 30 000 cycles. The energy density can be further improved to 53 Wh kg⁻¹ by replacing NaTi₂(PO₄)₃ with zinc anode. Furthermore, thanks to the extraordinary reaction kinetics of chlorine gas, this respiring supercapacitor performs an extremely high-power density of 50 000 W kg⁻¹.     

Interaction of –CClx (x=1–3) with Ru2 and RuSn dimers: a density functional study

Density functional calculation were performed on the Ru₂ and RuSn metal dimers and the species formed from their interaction with –CCl_x (x=1–3) fragments. The importance of these fragments in the hydrodechlorination of carbon tetrachloride has been motivated this study aiming to contribute to understand the effect of the tin in the performance of the noble metals based catalysts. We have observed that the carbon tetrachloride does not form a precursor with the metal dimers. The CCl₄ readily dissociates forming adsorbed chlorine and –CCl₃ complexes. The chlorine atoms prefer to adsorb on the bridge sites and the RuSn–Cl binding energy is about 5 kcal mol⁻¹ larger than the Ru₂–Cl binding energy. The Ru₂–CCl_x (x=1–3) binding energies are larger than the respective RuSn–CCl_x (x=1–3) binding energies. However, the reaction energy of the dechlorination of CCl₄ leading to adsorbed –CCl_x (x=1–3) and chlorine is thermodynamically more favorable for RuSn than the Ru₂. The differences between Ru₂ and RuSn systems have been discussed based on the different interaction mechanism due to the presence of the tin center and its affinity for the chlorine atoms.     

Ligandenaustauschreaktionen von Fluoratomen mit Chloratomen bei Phosphorverbindungen der Koordinationszahl 3 und 4

Ligand-exchange reactions of fluorine versus chlorine atoms in phosphorus compounds with coordination number 3 or 4 Fluorine versus chlorine ligand-exchange reactions were carried out on the following phosphorus-based central moieties: CH₃P <, CH₃P(O)<, CH₃P(S)< and CH₃P(Se)<. The measured equilibrium distributions were shown to favour the species which result from an accumulation of like substituents on the central moieties, whereas the equilibrium distribution of chlorine vs bromine on CH₃P(O) < was found to be almost random. These fluorine exchanging systems thus represent the unusual case of large positive deviation from random distribution. It is also noteworthy that the equilibrium distributions depend only very little on the nature of the atom which is bonded to phosphorus in the “isolated” position. System CH₃PF₂/CH₃PCl₂ could not be studied quantitatively owing to the competitive dismutation of CH₃PF₂; however, evidence is given for fast initial redistribution of the halogens on the methylphosphorus moiety and for the transient formation of CH₃PFCl.     

Abstraction of chlorine atoms from polychloroalkanes. II. Neighboring group effect on the rates of chlorine abstraction by cyclohexyl radicals

The kinetics of chlorine atom abstraction from trichloromethyl groups of the haloethanes (XCCl₃), CF₃CCl₃, CH₃CCl₃, C₂Cl₆, C₂Cl₅H, and CH₂ClCCl₃, by radiolytically generated cyclohexyl radicals was studied in the liquid phase by a competitive method. The chlorine atom abstraction data were put on an absolute basis by comparing the rates of the metathetical reactions with the known rate of addition of cyclohexyl radicals to C₂Cl₄. The following Arrhenius parameters were obtained: The error limits are the standard deviations from least mean square Arrhenius plots. It is shown that the neighboring group effect on the rate of chlorine atom abstraction from the trichloromethyl groups can be correlated with Taft polar substituent constants.     

Triäthanolaminkomplexe. II. Die Kristallstruktur von 2 ZnCl2 · C6H15O3N · H2O

The crystal structure of 2 ZnCl₂ · C₆H₁₅O₃N · H₂O has been determined by direct methods. The triethanolamine complex crystallizes in space group P 2₁/c with a₀ = 10.86, b₀ = 10.08, c₀ = 14.09 Å, β = 93.5° und Z = 4. The structure has been refined by least squares methods. Final R₁ index is 4.4% for 579 reflexions. One half of the zinc atoms are octahedrally coordinated by a chlorine atom, a water molecule and by the nitrogen and the three oxygen of the triethanolamine molecule. The other half is tetrahedrally surrounded by chlorine. The two zinc complexes are connected via a common chlorine atom.     

Solvent dependence of peak frequencies and bandwidths of the ν4 vibration of the series CH3MCl3, M  C,Si, Ge,Sn

The Raman spectra of the carbon—chlorine symmetric stretching mode, ν₄, of the Group IVA methylmetal trichlorides (CH₃MCl₃, M  C, Si, Ge, Sn) were acquired in a number of solvents of varying molecular properties. Non-linear curve fitting procedures were used to separate the four band components resulting from chlorine isotope splitting.The band maxima of the two lighter members of the series were observed to shift to lower frequency with increasing solvent polarizability, indicating the predominance of solute—solvent dispersion forces. In the germanium and tin compounds, on the other hand, the peak frequencies were correlated, instead, with solvent dipole moment. This result is in contrast to earlier studies on the ν₁ (CH₃ symmetric stretching) vibration, for which dispersion interactions are the dominant frequency displacement mechanism in all four compounds.The bandwidths of the ν₄ vibration were found to depend on dipolar interactions in the germanium and tin compounds. However, this correlation was not observed for the two lighter series members, nor for the carbon—chlorine antisymmetric stretching vibration in CH₃SnCl₃.     

Stoichiometry and products of ozone reaction with chloride ion in an acidic medium

It is shown by means of direct spectrophotometry in the UV and visible ranges that the only product of the O₃ reaction with Cl⁻(aq) in an acidic medium is molecular chlorine Cl₂; in solutions, it is in equilibrium with the complex ion Cl₃⁻. It is found that the consumption of one ozone molecule corresponds to the formation of one chlorine molecule. The stoichiometric equation for the reaction is obtained.     

Reactivity of main grouptransmittion metal bonds : III. Reactions of halogens with Ph3SiMn(CO)5 and Ph3SnMn(CO)5

The products of the reaction of Ph₃MMn(CO)₅ (M = Si or Sn) with chlorine, bromine and iodine in tetrachloromethane, have been determined.Ph₃SiMn(CO)₅ does not react with iodine, and the SiMn bond is cleaved by chlorine and by bromine.Ph₃SnMn(CO)₅ reacts in a much more complex manner, PhSn bond cleavage occurring with all three halogens to give mono-, di-, and, with the exception of iodine, tri-halogenated derivatives. Bromine, in high concentration, and iodine also cleave the SnMn bond.     

O2(1Δ) Yield Measurement by Raman Spectroscopy With Elimination of Chlorine Fluorescence Interference

Deleterious chlorine fluorescence was found to occur at the same frequency as the Raman scattering of O₂(1Δ) and O2(³∑), seriously affecting the O₂(1Δ) yield measurement in the re-action of chlorine with basic hydrogen peroxide by use of the Raman spectroscopy technique. To solve this problem we have taken advantage of the fact that Raman radiation is always strongly polarized while fluorescence is essentially non-polarized in a gaseous medium. When chlorine utilization of a singlet oxygen generator is 88%, O₂(1Δ) yield reaches (42.4±7.4)% with the effect of chlorine fluorescence completely eliminated.