CHCl2 Group Research Articles

Theoretical investigation on the kinetics of reaction of methoxyflurane (CH3OCF2CHCl2) with OH radical and its atmospheric impact

The H-abstraction reaction between methoxyflurane (CH3OCF2CHCl2) and OH radical is studied by employing the DFT-based M06-2X/6-311++G(d,p) method along with kinetic calculations by using the transition state theory (TST) and Eckart’s tunneling correction. The H-abstraction from the –CHCl2 group is found to be the most favorable reaction channel both kinetically and thermodynamically at lower temperature region. The rate coefficients for the title reaction are computed over a temperature range of 250–500 K and found to agree well with the available experimental values. Atmospheric lifetime, Radiative efficiency and Global Warming Potential (GWP) of CH3OCF2CHCl2 are also reported to highlight its atmospheric impact.

Computational study on night-time reaction of 1, 1-Dichlorodimethylether (DCDME) CH3OCHCl2 with NO3 radical and the fortuity of alkoxy radical CH3OC(O[rad])Cl2

Degradation of 1,1-Dichlorodimethylether by NO3 radical in the troposphere has been modelled theoretically by employing Gaussian09 suite at BHandHLYP/6-311++G(d,p) level. Energies of all optimized electronic structures have been further refined at CCSD(T) method along with the same basis set to characterize stationary points on the potential energy surface including transition states. The rate constants of the titled reaction are obtained over the temperature range 200–450 K. Results show that H-abstraction is highly favourable for CHCl2 group of CH3OCHCl2. The atmospheric lifetime and global warming potential of the titled molecule have been reported. The thermal decomposition of CH3OC(O)Cl2 has also been explored.

ATRA-like alkylation–peroxidation of alkenes with trichloromethyl derivatives by the combination of tBuOOH and NEt3

This protocol provides a unique and innovative approach to the construction of α-tert-butylperoxy-β-dichloromethyl alkanes, employing CHCl3 as an alkylating reagent to provide a –CHCl2 group, and TBHP as an oxidant to provide an α-tBuOO group.

A computational perspective on the kinetics and thermochemistry of the gas phase reactions of 1, 1-dichlorodimethylether (DCDME) with OH radical at 298 K

Kinetics and thermochemistry of the gas phase reactions between CH3OCHCl2 (DCDME) and OH radical are investigated theoretically. The geometries and all the stationary points on the potential energy surface are calculated at BHandHLYP/6-311G(d,p) method. The energy information is further refined at CCSD(T)/6-311G(d,p) level of theory. Reaction profiles are modelled including the formation of two pre-reactive and post-complexes. The rate constants, which are evaluated by Canonical Transition State Theory (CTST) including tunnelling correction at 298 K, are in very good agreement with the available experimental data. The percentage contributions of both reaction channels are also reported at 298 K. The hydrogen abstraction reaction from the –CHCl2 group is found to be dominant leading to the formation of CH3OCCl2 + H2O. Using group-balanced isodesmic reactions, the standard enthalpies of formation for CH3OCHCl2, CH3OCCl2 and CH2OCHCl2 are also reported.

Molecular structure and conformational transitions of dichloroacetylchloride

RHF and MP2 techniques in 6–31G(d) basis set have been used to determine the structure of the isolated molecule CHCl2COCl in two stable conformations (cis-and gosh-), as well as in transition states arising due to the rotary motion of CHCl2 group around the C—C bond. The energy gap between the conformers and the relevant potential barriers has been calculated using the obtained potential dependence of the internal rotation. Plausible conformation of dichloroacetylchloride is discussed on the basis of 35Cl NQR.

Structure of the Toxaphene Compound 2,5-endo,6- exo,8,9,9,10,10-Octachlorobornene-2: A Temperature-Dependent Formation of Two Rotamers

The irradiation of 2,2,3-exo,5-endo,6-exo,8,9,9,10,10-decachlorobornane in n-hexane at 254 nm leads to a spontaneous Cl2 elimination as the major reaction pathway. This results finally in the main product 2,5-endo,6-exo,8,9,9,10,10-octachlorobornene-2, of which the structure could be elucidated with the help of X-ray, 1H and 13C NMR, IR, and MS. Temperature-dependent 1H NMR spectroscopic investigations have shown that the -CHCl2 groups located at C1 and C7 are able to rotate slowly under normal circumstances. If such measurements, however, are exerted at low temperatures (-10 to -60 degrees C), so can be seen that two rotamers are formed due to the hindrance of the free rotation about the bonds C1-C10, C7-C8, and C7-C9, which for the first time could be revealed for a toxaphene compound. Furthermore, as all 1H NMR chlorobornane spectra known so far show only sharp and clear signals, it can be assumed that chlorobornane compounds as main toxaphene components have fixed bonds, which requires to indicate chlorine atoms within the tentacles such as "a", "b", and "c" for characterizing the correct position. Those fixed tentacles are probably the reason that many toxaphene congeners remain very stable in environmental compartments, and particularly the biotic and abiotic transformation may strongly be hindered by the inflexibility of the tentacles.

Conformational Analysis with Both Experimental and Computational Data for Both Gaseous and Crystalline Phases: Unexpected Interactions in N-Methyldichloroacetamide

The structure of N-methyldichloroacetamide (MeNHCOCHCl2) has been elucidated in the gaseous and solid states experimentally by gas electron diffraction and X-ray crystallography, and computationally with ab initio and plane-wave DFT methods. Although the main structural parameters generally agree well, the orientation of the CHCl2 group relative to the carbonyl oxygen was found to be very different in the solid and gas phases. X-ray crystallography and solid-state plane-wave DFT methods indicate that the bond torsion angle φ(HCCO) is 180.0°, while ab initio and gas electron diffraction methods return φ(HCCO) as −13.1° and −31.8(22)°, respectively. Further investigation of this phenomenon was carried out by using various computational methods. The possibility of intermolecular H···O and Cl···O bonds, which would stabilize the solid-state structure, was investigated by both solid-state plane-wave DFT and single-point ab initio methods. Ab initio SCRF calculations were also employed to evaluate solvent effec...

Studies of molecular dynamics of thiazides by35Cl NQR spectroscopy and DFT calculation

Molecular dynamics of three derivatives of 1,2,4-benzothiadiazine-1,1-dioxide, hydrochlorothiazide (HCTZ), althiazide (ATZ) and chlorothiazide (CTZ), was studied by35Cl nuclear quadrupole resonance (NQR) spectroscopy. The temperature dependence of the resonance frequency was analyzed within the 6 known standard models. The activation energies estimated from the temperature dependence of the35Cl NQR frequency assuming the Bayer model were 1.07, 2.35 and 2.76 kJ/mol for HCTZ, ATZ and CTZ respectively, which confirms that HCTZ is less rigid than CTZ and ATZ is much more rigid than HCTZ, and suggests that the mechanism of relaxation is based on small amplitude librations. The characteristic temperatures estimated from the Bayer model, with that for CTZ (332.5 K) being much higher than for HCTZ (132.1 K), mean that the intermolecular interactions in CTZ are much stronger than in HCTZ, as suggested by the melting point of CTZ being higher than that for HCTZ. For ATZ the characteristic temperature (288 K) takes an intermediate value, which suggests that the intermolecular interactions in this compound are stronger than in HCTZ and weaker than in CTZ. A significant narrowing of the resonance35Cl NQR line observed for all these compounds at room temperature, relative to that at the liquid nitrogen temperature, suggests an averaging of dipolar interactions as a result of fast rotation of nonquadrupole nuclei in the vicinity of the quadrupole nuclei, when 2πνQτc ≫ 1 (a rotation of the −NH2 group in the direct neighborhood of the chlorine nuclei) or a change in the gradient orientation with its value preserved (which is equivalent to rotation of the quadrupole nucleus Cl). The influence of the rotations of the −NH2 and −CH2SCH2CH=CH2 groups (ATZ) or −CHCl2 group (TCTZ) on the35Cl NQR frequency was modelled by the B3LYP/6-31G* method. The frequencies of the libration vibrations calculated from the temperature dependence of the NQR resonance frequency were compared with experimental ones and those implied by the density functional theory, infrared and Raman spectra. For HCTZ the anomalies in the temperature dependence of the35Cl NQR frequency, the lack of hysteresis and small but notable changes in the slope and the jump in the frequency observed at 253 K which does not exceed 0.05 MHz suggest a second-order phase transition at 253 K.

Study of the conformers of dichloromethylmethyldifluorosilane by vibrational spectroscopy and ab initio methods

Dichloromethylmethyldifluorosilane (CHCl2SiF2CH3) was synthesized for the first time. Raman spectra of the liquid were obtained at various temperatures between 298 and 163 K. Spectra of the amorphous solid were recorded at 85 K and spectra of crystalline solids cooled by different techniques were obtained. The infrared spectra were recorded of the vapor and of the amorphous and crystalline states at liquid nitrogen temperature. Two different crystals were observed after careful annealing of the amorphous solid to 202 K (crystal I) and 208 K (crystal II). Both the Raman and infrared spectra of these crystals were different, interpreted as different conformers being present in the two crystal lattices. When the liquid was cooled, crystal II was invariably formed, suggesting this crystal to be stable, whereas crystal I appeared to be metastable. Additional infrared spectra were obtained of the compound trapped in argon and nitrogen matrices at 5 and 15 K. The compound exists in two different conformations (anti and gauche) due to restricted rotation of the —CHCl2 group. Approximately 32 of the infrared and/or Raman bands present in the vapor and liquid vanished in one or other of the two crystals formed, giving 18 pairs of bands each belonging to one conformer. The remaining vibrational bands were present in both crystals, suggesting overlapping bands of the anti and gauche conformers. Raman temperature studies gave an enthalpy difference ΔHconf°=0±0.2 kJ mol-1 between the conformers in the liquid. The bands vanishing in the infrared matrix isolation spectra upon annealing to ca. 31–34 K suggested that the anti conformer had lower energy than gauche in both argon and nitrogen matrices, and the conformational barrier was estimated to be 6–7 kJ mol-1. Ab initio calculations at the HF/6–311G* level gave optimized geometries, infrared and Raman intensities and vibrational wavenumbers for the anti and gauche conformers. An assignment of the vibrational spectra into anti and gauche conformers was carried out and reasonably good agreement was obtained between the experimental and scaled ab initio calculated wavenumbers for the two conformers. © 1998 John Wiley & Sons, Ltd.

Effects of 35Cl/37Cl, 13C Residual Dipolar Coupling on the Variable‐Temperature 13C CP/MAS NMR Spectra of Solid, Chlorinated Sodium Acetates

Agreement between theory and practice: Solid‐state NMR studies on organic compounds with CH2Cl, CHCl2, and CCl3 groups show that residual dipolar coupling between 35Cl/37Cl and 13C nuclei influences the splitting of the signals depending on the magnetic field strength B. When molecular motions are slow enough to prevent self‐decoupling, signals for C nuclei affected by a single Cl nucleus appear as symmetric doublets at B0 >5 T and as asymmetric triplets at lower fields.

Factors Affecting Infrared Group Frequencies: Carbonyl Stretching Absorption Bands

The data presented show that infrared group frequencies are only applicable for specific spectra structure identification when the infrared spectrum of the unknown material is recorded in the same manner as that used to record the infrared spectra used to build the IR group-frequency data base. IR spectra recorded of compounds in different phases such as the liquid, solution, and vapor phase are useful in helping one to determine whether a compound exists in more than one rotational molecular configuration such as rotation of a CHCl2 group about a C-C=O single bond in compounds of form CHCl2-C=O.

The Infrared Spectra of Dichloroacetic Acid Derivatives: Characteristic Absorption Frequencies of the -CHCl2 Group

The infrared spectra of seven compounds containing the -CHCl2 group attached to various carbonyl functionalities have been carefully recorded under a variety of conditions. Group frequency ranges for the CH, CC, and CCl (two) stretching modes and two CH bending modes have been developed. With the exception of the CC stretching mode, these vibrations fall in rather narrow regions of the spectrum. The conformational equilibria present in chlorine-substituted acetic acid derivatives are reflected by their infrared spectra in various ways. The situation with regard to the observed carbonyl stretching frequencies as related to conformational equilibria is reviewed.

Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, XLVII [1]. Einschiebungsreaktionen von phasentransferkatalytisch in situ erzeugten Dihalocarbenen in P-haltige Manganacycloalkane – Struktur und chemisches Verhalten der Reaktionsprodukte / Preparation and Properties of and Reactions with Metal-Containing Heterocycles, XLVII [1]. Insertion Reactions of Phase-Transfer-Catalytically in situ Generated Dihalocarbenes into P-Containing Manganacycloalkanes – Structure and Chemical Behaviour of the Reaction Products

Abstract The phase-transfer-catalytically in situ generated dihalocarbenes CCl2 and CBr2 are inserted into a β-C-H bond of the five-and six-membered phosphamanganacycloalkanes (OC)4[xxx] (1a, b) [n = 1(a), 2(b)] to give the functionalized metallacycles (OC)4[xxx](2a, a′, b, b′) [X = Cl: n = 1(a), 2(b); X = Br: n = 1(a′), 2(b′)]. 2b crystallizes in the orthorhombic space group Pbca with Z = 8 and has a distorted chair conformation with equatorial position of the CHCl2 group. The envelope conformation of 2a in solution was elucidated by means of 1H and 13C{1H} NMR spectroscopic investigations.

The individual CH bond as a Raman spectroscopic probe to the internal rotation of the CHCl2 Group in C6H5CHCl2

AbstractEvidence is provided concerning the internal rotation of the CHCl2 group in the C6H5CHCl2 molecule in the condensed phase using mainly the Raman spectra of the alkylic carbon‐hydrogen stretching vibration of C6H5CHCl2 and its deuteriated analogues. Comparison of the Raman bands observed in the region of the CH stretching vibrations for the hydrogenated compound with its deuteriated derivatives allows the assingnment of two Raman bands to the CH vibrator of the CHCl2 group. The dependence of the profiles of these bands on temperature and dilution in a series of solvents suggests a conformational equilibrium. Comparision of two different theoretical treatments of the isolated molecule enables us to reconize the importance of non‐boarded interactions operating during the internal rotation of the dichloromethyl group. The experimental results, used together woth the theoretical studies, lead to the evidence for two probable rotational isomers, designated CH⊥ and CH‖ which are responsible for the two observed Raman bands.

Reduction of trichloromethyl group to the dichloromethyl group by thiols in the presence of metal carbonyls

1. The carbonyls Fe(CO)5, Mn2(CO)10, Mo(CO)6, and W(CO)6 initiate the selective reduction of the CC13 group to the CHCl2 group by thiols. The reduction systems thiol + Mn, Mo, and W carbonyls have been used for the first time. 2. The reduction of CCl3(CO2)nCl (n=4, 6, 8), CCl3(CH2)5CH3, CCl3CH2CH(CH3)CH2CHCl-CH3, and CCl3CHC1(CH2)3Cl showed that Fe(CO)5 and Mn2(CO)10 were the most effective initiators.

Transformation of chlorofluoroethyldiethylamines to N,N-diethyldifluoroacetamide

Hydrolysis of 2-chloro-1,1,2-trifluoroethyldiethylamine (I) and 2,2-dichloro-1,1-difluoroethyl-diethylamine (II) in the presence of triethylamine afforded N,N-diethylchlorofluoroacetamide (VII) and N.N-diethyldichloroacetamide (VIII), respectively. Triethylamine hydrofluoride, arising in the reaction, was used for fluorination and transformation of the amides VII and VIII to N,N-diethyldifluoroacetamide (VI). The C-Cl bond of the CHClF group in VII proved to be more reactive in nucleophilic substitution with fluoride ion than the corresponding bond in the CHCl2 group of VIII.

ChemInform Abstract: REARRANGEMENT OF POLYCHLOROALKYL RADICALS WITH 1,4, 1,5, AND 1,6 MIGRATION OF HYDROGEN ATOM

1. During the reduction of 1,1,1,7-tetrachloroheptane with isopropanol in the presence of Fe(CO)5, together with the main reaction product 1,1,7-trichloroheptane (II), 1,1,5,7-tetrachloroheptane (III), 1,1,4,7-tetrachloroheptane (IV) and 7,7-dichloro-1-heptene (V) are formed in a total yield of 7% of theoretical. 2. The formation of (III), (IV), and (V) is explained by an unusual rearrangement of the CCl2(CH2)6Cl radicals into less stable radicals with 1,5-, 1,4-, and 1.6-migration of hydrogen atoms, respectively, with preferential formation of the rearrangement product and 1,5-migration of the hydrogen atom. 3. Certain regularities in the13C NMR spectra of polychlorohydrocarbons with a normal structure, containing the CHCl2, CH2Cl, and CHCl groups with different disposition of the CHCl group in the chain are discussed.

Rearrangement of polychloroalkyl radicals with 1,4-, 1,5- and 1,6-migration of hydrogen atom

1. During the reduction of 1,1,1,7-tetrachloroheptane with isopropanol in the presence of Fe(CO)5, together with the main reaction product 1,1,7-trichloroheptane (II), 1,1,5,7-tetrachloroheptane (III), 1,1,4,7-tetrachloroheptane (IV) and 7,7-dichloro-1-heptene (V) are formed in a total yield of 7% of theoretical. 2. The formation of (III), (IV), and (V) is explained by an unusual rearrangement of the CCl2(CH2)6Cl radicals into less stable radicals with 1,5-, 1,4-, and 1.6-migration of hydrogen atoms, respectively, with preferential formation of the rearrangement product and 1,5-migration of the hydrogen atom. 3. Certain regularities in the13C NMR spectra of polychlorohydrocarbons with a normal structure, containing the CHCl2, CH2Cl, and CHCl groups with different disposition of the CHCl group in the chain are discussed.

Isotope Effect of the Pure 35Cl and 37Cl Quadrupole Resonance Spectra in CHCl2COOH and CDCl2COOD

Abstract The temperature dependence of the pure nuclear quadrupole resonance of 35Cl and 37Cl in solid CHCl2COOH and CDCl2COOD has been measured. The spectra are doublets according to two dif­ferent sites, Cl (I) and Cl (II), of the chlorine atoms in the CXCl2 group (X = H,D). In CHCl2COOH and CDCl2COOD the 37Cl spectra became unobservable above 198 K and 175 K and the 35Cl spectra vanished at 238 K and 226 K, respectively. The temperature dependence was calculated using the Bayer-Kushida theory which gives a satisfactory approach in the case of the compounds investigated here. A small difference has been found in the temperature dependence of the resonance frequen­ cies for CI (I) and CI (II) in both the CHCl2 and CDCl2 group, which is probably due to differences in the bond lengths of CI (I) and CI (II). Furthermore, there is a different temperature dependence of the resonance frequencies of the chlorine isotopes at the sites CI (I) and CI (II). This gives evi­ dence for the so-called isotope effect: i. e. there are slightly different thermal motions for the chlorine isotopes which are involved in the averaging of the electric field gradient tensor. The re­ placement of protons by deuterons gave a shift of the resonance frequencies of about 20 kHz to lower values. This may be primarily caused by effects of deuteration on the electronic structure.

Dynamic Structure of Water in Aqueous Solutions of Chloroacetate. I. Temperature Dependence of Limiting Mobilities of Mono-, Di-, and Tri-chloroacetate Ions

Abstract Electric conductivities of the sodium salts of mono-, di-, and tri-chloroacetic acids were measured in water at 15, 25, and 35 °C. The molar conductivities were analyzed by the Fuoss-Onsager equation to obtain the limiting mobility. On the basis of the temperature dependence of the limiting mobilities, the dynamic structure of Water around these anions was investigated by means of Samoilov’s theory, Chloroacetate ions are structure maker and the degree of the positive hydration is in the order TCA−>acetate ion>DCA−>MCA−. From the results, it is shown that a competition between the different orientation of water molecules in the surroundings of –CH2Cl and –CHCl2 groups occurs, and consequently, shown that the water molecules around DCA− and MCA− ions more mobile than those around TCA− and acetate ions.