A Facile Route to Unsymmetrical Sulfide

Unsymmetrical sulfides can be generated by the reaction of chlorine substituted aromatic compounds in sulfoxide in the presence of fluorine anion in fair yield.A likely mechanism was proposed.     

Certified reference materials for the quality control of fluorine in coal, fly ash and clay

A group of laboratories has worked in various intercomparisons in the frame of the BRC-programme (European Commission) to improve their methods for fluorine determination, especially for coal analysis. These exercises allowed to detect and remove sources of error. Methods were improved to such an extent that the certification of fluorine and chlorine in different materials could be envisaged and the BCR consequently decided to produce coal, fly ash and clay materials certified for their F content. In addition, chlorine was certified in the fly ash CRM.     

Controlled chlorine plasma reaction for noninvasive graphene doping

We investigated the chlorine plasma reaction with graphene and graphene nanoribbons and compared it with the hydrogen and fluorine plasma reactions. Unlike the rapid destruction of graphene by hydrogen and fluorine plasmas, much slower reaction kinetics between the chlorine plasma and graphene were observed, allowing for controlled chlorination. Electrical measurements on graphene sheets, graphene nanoribbons, and large graphene films grown by chemical vapor deposition showed p-type doping accompanied by a conductance increase, suggesting nondestructive doping via chlorination. Ab initio simulations were performed to rationalize the differences in fluorine, hydrogen, and chlorine functionalization of graphene.     

5- and 7-substituted 2-methyl-8-quinolinols

The synthesis and characterization of the 5- and 7-monosubstituted 2-methyl-8-quinolinols where the substituents are fluorine, chlorine, bromine, iodine, nitro, amino, and sulfonic acid groups were carried out. The bischelates with copper(II) of those ligands containing hydrogen, fluorine, chlorine, bromine, iodine, and nitro are also reported.     

Bombes calorimetriques en atmosphere fluorante

Several calorimetric bombs models using fluorine gas or other volatils fluorinated compounds are described for gas/gas, liquide/gas and liquide/liquide reactions.Five experiments and results are given.     

Comparative study of activation analyses for the determination of trace halogens in geological and cosmochemical samples.

Halogens (fluorine, chlorine, bromine and iodine) were determined by activation analyses (neutron activation analysis (NAA), photon activation analysis (PAA) and prompt gamma-ray analysis (PGA)) for geological and cosmochemical solid samples. We studied how each analytical method was for the determination of trace amounts of halogens in rock samples. Radiochemical NAA (RNAA) showed the highest analytical reliability for three halogens (chlorine, bromine and iodine), whereas a set of four halogens (fluorine, chlorine, bromine and iodine) could be determined in principle by radiochemical PAA (RPAA) from a single specimen. Although it is a non-destructive method, PGA showed an analytical sensitivity for chlorine comparable to those of RNAA and RPAA.     

Determination of fluorine in silicate and phosphate rocks,micas and stony meteorites

By making certain modifications to a published procedure for fluorine in rocks, it has been possible to improve stability and extend the range of the method. The modified method has been successfully applied to silicate and phosphate rocks, micas, glass and stony meteorites, containing from 60 p.p.m. to 8% fluorine. Some precautions are recommended for reliable determination of chlorine.     

Adsorption and sequential thermal release of F2, Cl2, and Br2 molecules by a porous organic cage material (CC3-R): Molecular dynamics and grand-canonical Monte Carlo simulations

The adsorption–desorption behavior of fluorine, chlorine, and bromine molecules onto a crystalline porous organic cage, namely CC3-R was calculated at different temperatures using molecular dynamics (MD) and grand-canonical Monte Carlo (GCMC) simulations. Self-diffusion coefficients, radial distribution functions (RDF), and adsorption isotherms were calculated for this purpose. The results show that CC3-R has varied capacities to capture these halogens at ambient and high temperatures, so that the thermal release of fluorine is completed with increasing temperature up to around 70°C and chlorine molecules remain at the CC3-R surface up to 100°C and all bromine molecules are removed from the CC3-R surface at 200°C. We found that bromine self-diffusion was almost independent of temperature between 0 and 100°C in contrast to fluorine and chlorine. Among different diffusion regimes, Knudsen diffusion appears to have an important role in the adsorption of heavy halogens at higher temperatures.     

离子色谱测定农用硫酸铵中4种杂质阴离子

建立了离子色谱法同时测定农用硫酸铵中氟、氯、溴、硫氰酸盐的分析方法。样品经水提取,Ba离子柱净化后,离子色谱法测定。4种阴离子浓度在各自线性范围内与相应峰面积呈线性关系,相关系数r＞0.999,加标回收率为80.23%～111.50%,精密度（RSD）为0.62%~9.08%。称样量为0.1g时,氟、氯的方法检出限为10mg/kg;溴、硫氰酸盐方法检出限为20mg/kg。该方法样品前处理简单、快捷,重复性及回收率均能达到检测分析要求,可以应用于农用硫酸铵中杂质阴离子的检测。     

石墨炉碱溶消解-离子色谱法同时测定硫磺中氟、氯,硫酸根

建立了石墨炉碱溶消解-离子色谱法同时测定硫磺中氟、氯、硫元素的方法,选择各元素的分析谱线,采用外标法绘制曲线,方法的检出限0.0019~0.022μg/mL,方法的加标回收率在81.0%~113%,测定值的相对标准偏差(n=5)小于3.4%。方法的研究成功填补了硫磺中氟、氯、硫酸根测定的空白。     

Direct and initiated halogenation of carbon nanomaterials at low temperatures

Cryochemical reactions of the direct and initiated (by photolysis and radiolysis) halogenation of carbon nanomaterials (C₆₀ fullerene, nanotubes, and nanofibers) at 77–240 K were investigated by the ESR, IR spectroscopy, and elemental analysis techniques. A high reactivity of C₆₀ in reactions with fluorine and chlorine with the formation of corresponding derivatives was shown. High concentrations of radical intermediates indicating the radical chain halogenation of C₆₀ were detected (the kinetic chain length for the chlorination process reaches 10⁴–10⁶ units). The amount of chlorine attached to fullerene is ～35% and practically does not depend on the initiation mode (UV or γ-irradiation at doses up to 350 kGy). The mechanism of the cryochemical halogenation of C₆₀ is considered within the limits of the model of multicenter synchronous transitions in a molecular complex consisting of several reactant molecules including molecular fluorine or chlorine and ensuring a net exothermic effect. The amount of chlorine added to nanotubes and nanofibers did not exceed 2.5–8%, thereby indicating a low reactivity of these materials under cryogenic conditions.     

The trifluoromethoxy group as a fluorine twin in the Diels-Alder reactions of halogenated quinones

We describe here a study devoted to the comparison of the relative influence of chlorine, fluorine, and trifluoromethoxy substituents on the regiochemical outcome of the Diels-Alder reaction. For this purpose, we examined the behavior of mixed ‘halogenated’ quinones bearing these groups in their cycloadditions with simple dienes. Contrary to the expectation based on its known electronic properties, the trifluoromethoxy group behaves very much more like a fluorine than a chlorine atom in such reactions. On the basis on an endo transition state demonstrated here for these additions, we tentatively suggest that non-bonded interactions are the main factor controlling the regiochemistry.     

Spin-spin coupling and substituent and halogen isotope shift effects in the fluorine NMR spectra of fluorinated cyclopropanes and cyclopropyl ethers

The (19)F NMR spectra of a series of fluorinated cyclopropanes, most of which contain chlorine or bromine on the ring, have been observed and analyzed. A scheme has been developed to assign the resonances and the molecular stereochemistry, based on substituent effects, comparison of related molecules, and isotope shifts induced by the halogens. Replacement of fluorine by chlorine shifts cis fluorine resonances to lower field, and bromine has an even greater downfield influence. However, the shift effect of bromine compared to chlorine on gem or trans fluorines is variable. The magnitude of the isotope shifts is found to be regularly related to the geometrical relationship of the halogen to the observed fluorine and thus makes a significant contribution to the fluorine assignments. The three-bond spin-spin coupling constants between fluorine atoms in cyclopropanes display unusual behavior and are not helpful for assignment of the fluorine resonances. The signs of the coupling constants have been investigated by spin-tickling experiments, and the previously developed relation of the coupling constant sign to its temperature dependence has been found to be violated for some molecules.     

氟氯有机化合物对HZSM-5分子筛改性过程中氟和氯的作用

利用ＸＲＤ，ＭＡＳ，ＮＭＲ，ＩＲ和ＸＰＳ等手段研究了ＣＦ４－ｎＣｌｎ改性的ＨＺＳＭ－５分子筛的体相和表面结构的变化。结果表明，改性过程中Ｆ和Ｃｌ均能使ＨＺＳＭ－５脱铝和脱硅。Ｃｌ可以使沸石骨架ＳｉＯ２／Ａｌ２Ｏ３升高，而Ｆ除使沸石骨架脱铝外，还会极化其晶格。Ｆ比Ｃｌ更容易在沸石表面富集。Ｆ和Ｃｌ是通过取代Ｏ或ＯＨ与沸石表面Ｓｉ或Ａｌ作用的。改性后的沸石表面有数种含氟表面物种存在。     

Preparation and characterization of simple dihalomethylidene platinum dihalide complexes in reactions of laser-ablated Pt atoms with tetrahalomethanes

Platinum atoms react with tetrachlorofluoromethanes upon laser-ablation and with ultraviolet irradiation to form dihalomethylidene platinum dihalide complexes, CX(2)=PtX(2). These new molecules are identified from carbon-13 and chlorine isotopic shifts, displacements in functional group frequencies as chlorine is replaced with fluorine, and comparison to frequencies calculated by density functional theory. The PtC bond lengths calculated here, 1.810 to 1.816 A, are shorter than analogous bond lengths measured earlier for Pt(II) carbene complexes (1.943-1.950 A). The computed effective Pt-C bond orders range from 1.41 to 1.70 as chlorine is replaced by fluorine since the more electronegative halogen appears to concentrate the Pt 5d orbitals and make them bond better with carbon. These platinum methylidene complexes thus have a substantial amount of double bond character from d(pi)-p(pi) bonding.     

Zur Dismutierung von C1-Fluorchlorkohlenwasserstoffen an Metalloxid- und Halogenidoberflächen

Dismutation of C₁ – Fluorine Chlorine Hydro Carbons at Surfaces of Metal Oxides and halides Dismutation of C₁-fluorine chlorine hydro carbons has been investigated at surfaces of aluminium and chromium chlorides respectively fluorides. Dismutation reactions have been observed only after halogen exchange at such surfaces of solids which contain both, chloride and fluoride. A mechanism of dismutation is suggested which underlies a concerted chlorine/fluorine and fluorine/chlorine exchange between the solid and the gas phase. The results are discussed in connection with thermodynamically considerations.     

Removal of fluorine from and introduction of fluorine into polyhalopyridines: an exercise in nucleophilic hetarenic substitution

Starting from six industrially available fluorinated pyridines, an expedient access to all three tetrafluoropyridines (2-4), all six trifluoropyridines (5-10), and the five non-commercial difluoropyridines (11-14 and 16) was developed. The methods employed for the selective removal of fluorine from polyfluoropyridines were the reduction by metals or complex hydrides and the site-selective replacement by hydrazine followed by dehydrogenation-dediazotation or dehydrochlorination-dediazotation. To introduce an extra fluorine atom, a suitable precursor was metalated and chlorinated before being subjected to a chlorine/fluorine displacement process.     

Joint determination of fluorine and chlorine in granitic rocks with ion-selective electrodes

This enables both fluorine and chlorine in granitic rocks to be determined with a single sample. A rapid technique, using fusions in culture tubes, and a slower technique, employing fusions in platinum crucibles are described. The culture-tube technique is suitable for geochemical exploration and employs an oxidizing flux so that sulphide-bearing rocks can be analysed. The platinum-crucible technique yields fluorine and chlorine results for the standard rocks G-2 and GSP-1 that are comparable in value and precision to those obtained by other analytical methods. It is faster, easier to manipulate and yields higher fluorine values than the existing joint spectrophotometric method.     

大同烟煤增压富氧燃烧过程中硫、氯和氟的析出特性

利用高压热重结合傅里叶红外研究了大同烟煤在增压富氧燃烧过程中硫、氯和氟的释放行为,主要考察压力对其析出特性的影响。实验结果表明,压力的改变对煤中硫、氯和氟的迁移转化均有显著影响。随着压力的升高,黄铁矿硫向COS等中间产物的转化率逐渐增加,导致SO2的收率逐步上升,但在3 MPa时,燃煤SO2收率却有所降低。此外,压力升高后反应气氛中CO分压的增加促进了COS的生成,导致其收率逐渐上升。因为煤中有机氯析出和转化与挥发分的释放密切相关,所以高压下挥发分释放量的增加使得煤中有更多的有机氯析出并转化为HCl,而且压力升高后,挥发分燃烧速率和温度的升高促进了无机氟化物分解,HF生成量相应增加。此外,高压下水解反应的强化也提高了HF的收率。     

Fluorinated heterocyclic compounds: Selective chlorine/fluorine exchange reactions on pyrimidines

Selective chlorine/fluorine exchange reactions on tetrachloropyrimidine, 6-methyl-, 6-chloromethyl-, 6-dichloromethyl-, and 6-trichloromethyl-2,4,5-trichloropyrimidine are described. Sodium fluoride, potassium fluoride, hydrogen fluoride, and antimony trifluoride were used as the fluorinating agents. It was found that NaF and KF fluorinate only in the heterocyclic nucleus, HF in the nucleus and in the chlorinated methyl group, and SbF₃ only in the chlorinated methyl group. In the first stage of fluorination with NaF only chlorine bound in position 4 of the pyrimidine ring is exchanged. The HF reaction is an equilibrium reaction in which the substitution of the fluorine for the first chlorine atom occurs preferentially in position 2. The behaviour of partly fluorinated pyrimidines in nucleophilic exchange reactions is also discussed.