Deuterium Chloride Research Articles

Solvent‐Free Hydrohalogenation and Deuteriohalogenation by Ex Situ Generation of HX and DX Gas

AbstractThe hydrohalogenation of olefins is one of the most straightforward methods to access alkyl halides. Despite safety hazards, using pure hydrogen halide gas remains the most atom economic way of performing hydrohalogenation reactions. In this work, we describe the solvent‐free hydro‐ and deuteriohalogenation of olefins using down to near‐stoichiometric amounts of hydrogen and deuterium halide gas. Two‐chamber reactors are employed as an enabling platform to access these reactive gases in a laboratory setting. Ex situ generation from inexpensive and readily available precursors provides on‐demand access to these gases (hydrogen chloride, deuterium chloride, hydrogen bromide, deuterium bromide, hydrogen iodide, and deuterium iodide) with precise stoichiometric control. Upon chemo‐ and regioselective conversion of the substrate, the halide products may be isolated without the need for any work‐up or purification steps making it a clean and labor‐, waste‐ and cost‐effective method.

Evidence for Oxonium Ions in Ethereal "Hydrogen Chloride".

Although solutions of hydrogen chloride in ethereal solvents like diethyl ether or dioxane are commonly employed in the laboratory, the solution structure of these reagents has yet to be firmly established. Here, we analyze solutions of ethereal hydrogen chloride or deuterium chloride in toluene, in dichloromethane, or in the absence of a co-solvent by in situ infrared spectroscopy. The resulting spectra are inconsistent with free HCl or often-proposed 1:1 HCl-ether complexes but closely match the predicted spectra of oxonium ions generated via protonation of diethyl ether. Molecular dynamics simulation of the oxonium chloride complexes provides evidence for an outer-sphere contact ion pair. These results suggest new approaches for tuning the acidity of strong Brønsted acids in organic solvents and demonstrate the importance of conducting spectroscopic measurements under reaction-relevant conditions.

Aspartic acid enantiomer quantification using ultraperformance liquid chromatography–tandem mass spectroscopy combined with deuterium‐chloride hydrolysis to improve age estimation in Antarctic minke whale Balaenoptera bonaerensis

AbstractAspartic acid racemization is a useful tool for estimating age in marine mammals; however, acid hydrolysis during sample preparation may increase the D‐ to L‐enantiomer ratio. To improve age estimation in Antarctic minke whale (Balaenoptera bonaerensis), we optimized the quantification of aspartic acid enantiomers in ocular lens by using ultraperformance liquid chromatography–tandem mass spectrometry combined with sample preparation by hydrolysis with deuterium chloride. Using this approach, we determined D/L in fetal and adult whale lens, examined the degree of racemization induced by acid hydrolysis, and constructed equations for age estimation. In the fetal lens, D/L obtained after hydrolysis with HCl or DCl were positively correlated with gestation age. Estimates of D/L at birth using a DCl‐hydrolysis model were much lower than those obtained using a HCl‐hydrolysis model, indicating that racemization during hydrolysis with HCl reduces the precision of subsequently derived age estimates. Furthermore, the D/L0 unaffected by Asp‐D generated during hydrolysis was estimated. The loge[(1 + D/L)/(1 − D/L)] value was exponentially increased with increasing earplug‐derived age, and the standard error of the age estimates after hydrolysis with DCl was lower than that after HCl. We conclude that our method can provide precise age estimates without methodological bias.

Raman spectroscopy study of the slow order-order transformation of deuterium atoms: Ice XIX decay and ice XV formation.

The nature of the hydrogen substructure of a deuterated and deuterium chloride (DCI)-doped ice VI sample after cooling at 1.8GPa has been a topic of recent interest-especially because the novel ice polymorph ice XIX was discovered in the course of such studies. We here investigate deuterated samples containing 5% H2O using Raman spectroscopy to probe for transitions associated with rearrangement of D-atoms in ice XIX. The protocol involving heating at subambient pressure (10mbar) in this study follows closely the one used in our earlier neutron diffraction study. Heating of ice XIX induces a complex cascade of processes involving both ordering and disordering of D atoms. Our Raman spectra demonstrate that the transition sequence is ice XIX → ice VI‡ → ice XV, in accordance with our earlier neutron diffraction result. First signs for ice XIX decay are evident at 100K, while ice XV build-up is seen only at 108K and above. Between 100 and 108K, a transiently disordered D-substructure appears, where at 108K, ice VI‡ forms from ice XIX and simultaneously decays to produce ice XV-thereby establishing a dynamic equilibrium. Using isothermal, time-resolved Raman spectroscopy in real time, we here determine rate constants, Avrami exponents, and activation energies for both slow processes, ice XIX decay and ice XV build-up. The first transition in this sequence, ice XIX decay, is faster than the second transition, ice XV build-up, so that ice VI‡ accumulates. On the basis of the Johnson-Mehl-Avrami-Kolmogorov data obtained from the isothermal Raman experiment, we additionally report kinetic models for the development of fractions of ices XIX, XV, and VI‡ in non-isothermal heating experiments at different heating rates. These models consider the two coupled first-order transitions as separated processes, where the phase fractions are calculated for incrementally small temperature (or time) steps. These models compare favorably with our previous observations for slowly or rapidly heated ice XIX samples, such as in calorimetry or neutron diffraction experiments.

Electrochemical Generation of Individual Nanobubbles Comprising H2, D2, and HD.

The electrochemical reduction of deuterons (2D+ + 2e- → D2) at Pt nanodisk electrodes (radius = 15-100 nm) in D2O solutions containing deuterium chloride (DCl) results in the formation of a single gas nanobubble at the electrode surface. Analogous to that previously observed for the electrochemical generation of H2 nanobubbles, the nucleation and growth of a stable D2 nanobubble is characterized in voltammetric experiments by a highly reproducible and well-resolved sudden drop in the faradaic current, a consequence of restricted mass transport of D+ to the electrode surface following the liquid-to-gas phase transition. D2 nanobubbles are stable under potential control due to a dynamic equilibrium existing between D2 gas dissolution and electrochemical generation of D2 at the circumference of the Pt nanodisk electrode. Remarkably, within the error of the experimental measurement (<6%), the electrochemical current required to nucleate a D2 gas phase in a D2O solution is identical to that for the H2 gas phase in a H2O solutions, indicating that the concentration required for nucleating a D2 nanobubble in D2O (0.29 M) is ∼1.25 times larger than that for a H2 nanobubble (0.23 M), while the supersaturation is ∼300 in each case. We further demonstrate that individual nanobubbles can be electrogenerated in mixed D2O/H2O solutions containing both D+ and H+ at respective individual concentrations well below those required to nucleate a gas phase containing either pure D2 or H2. This latter finding indicates that the resulting nanobubbles comprise a mixture of D2, H2, and HD molecules with the chemical composition of a nanobubble determined by the concentrations and diffusivities of D+ and H+ in the mixed D2O/H2O solutions.

Quantum State and Doppler-Resolved Scattering of Thermal/Hyperthermal DCl at the Gas–Liquid Interface: Support for a Simple “Lever Arm” Model of the Energy-Transfer Dynamics

Supersonically cooled deuterium chloride (10 K, DCl(J ≈ 0, 1)) has been scattered from the gas–liquid interface under thermal (Einc = 1.5(1) kcal/mol) and hyperthermal (Einc = 11.5(5) kcal/mol) conditions for a series of prototypical liquids (perfluoropolyether (PFPE), squalane, and glycerol), with the final DCl quantum states detected with narrow-band IR laser absorption methods to achieve rotational (J) and transverse Doppler (vy) resolutions. First of all, we see direct evidence for both trapping desorption (TD) and impulsive scattering (IS) components in the DCl distributions, with both TD rotational and transverse velocity components fully equilibrated with the liquid (TS ≈ Trot ≈ TDopp). Second, high-resolution laser dopplermetry on the IS component reveals quite efficient transfer from Einc into out-of-plane scattering of the DCl, in contrast with the notably inefficient channeling of the collision energy into end-over-end rotation. Third, though the rotational excitation efficiency is low, the imp...

A d-Amino Acid-Containing Neuropeptide Discovery Funnel.

A receptor binding class of d-amino acid-containing peptides (DAACPs) is formed in animals from an enzymatically mediated post-translational modification of ribosomally translated all-l-amino acid peptides. Although this modification can be required for biological actions, detecting it is challenging because DAACPs have the same mass as their all-l-amino acid counterparts. We developed a suite of mass spectrometry (MS) protocols for the nontargeted discovery of DAACPs and validated their effectiveness using neurons from Aplysia californica. The approach involves the following three steps, with each confirming and refining the hits found in the prior step. The first step is screening for peptides resistant to digestion by aminopeptidase M. The second verifies the presence of a chiral amino acid via acid hydrolysis in deuterium chloride, labeling with Marfey’s reagent, and liquid chromatography–mass spectrometry to determine the chirality of each amino acid. The third involves synthesizing the putative DAACPs and comparing them to the endogenous standards. Advantages of the method, the d-amino acid-containing neuropeptide discovery funnel, are that it is capable of detecting the d-form of any common chiral amino acid, and the first two steps do not require peptide standards. Using these protocols, we report that two peptides from the Aplysia achatin-like neuropeptide precursor exist as GdYFD and SdYADSKDEESNAALSDFA. Interestingly, GdYFD was bioactive in the Aplysia feeding and locomotor circuits but SdYADSKDEESNAALSDFA was not. The discovery funnel provides an effective means to characterize DAACPs in the nervous systems of animals in a nontargeted manner.

Identification of nitrate source using isotopic and geochemical data in the lower reaches of the Yellow River irrigation district (China)

Nitrate contamination in both surface water and groundwater has received considerable attentions in irrigated agricultural areas. Nitrate concentrations, and its nitrogen and oxygen isotopic compositions, as well as oxygen and deuterium isotopic compositions and chloride concentrations of surface water and groundwater from a typical area in the lower reaches of the Yellow River irrigation district were analyzed to ascertain spatial variations of nitrate and its possible sources and transformations. The results of this study showed nitrate in the Yellow River mainly derived from mineralization of organic matter in sediments and nitrification of atmospheric deposition, and nitrate in other important tributaries were greatly affected by agricultural activities, especially synthetic fertilizer. Nitrate in irrigation canals which go through concentrated residential zone mainly originated from domestic effluent and experienced nitrification. Nitrate in groundwater is not only affected by surface nitrate sources, but also closely related to hydraulic conditions which make nitrate source discrimination more complex. In areas belonging to the Yellow River basin with shallow water tables, nitrate is mainly derived from synthetic fertilizer, and denitrification processes controlled nitrate isotopic compositions in extremely shallow groundwater with low hydraulic gradients. While in places belonging to the Haihe River basin with deep water table, groundwater nitrate is largely affected by mixing process of irrigation water. The main sources of nitrate in groundwater are manure and sewage and soil organic matter, while chemical fertilizer and atmospheric deposition in large amount of rainfall are its minor contributors.

Convergent Synthesis of Solamargine and Analogues Thereof: Structural Revision of 16‐epi‐Solamargine and Cytotoxic Evaluation

AbstractAn effective and stereoselective protocol for convergent synthesis of solamargine, a representative of spirosolane‐type glycoalkaloids, is reported. HB(C6F5)4‐catalyzed coupling of 26‐azido‐pseudodiosgenin with chacotriosyl trichloroacetimidate as the key step for synthesis of solamargine proceeded in high yield and with excellent stereoselectivity. Three analogues of solamargine were synthesized by the method. Protonation of the nitrogen atom by deuterium chloride had a significant influence on the 1H NMR spectrum of solamargine. On the basis of these results, the structure of 16‐epi‐solamargine was revised to solamargine hydrochloride. The cytotoxicity of solamargine together with its analogues against cancer cell lines was evaluated.

Six-dimensional quantum dynamics study for the dissociative adsorption of DCl on Au(111) surface.

We carried out six-dimensional quantum dynamics calculations for the dissociative adsorption of deuterium chloride (DCl) on Au(111) surface using the initial state-selected time-dependent wave packet approach. The four-dimensional dissociation probabilities are also obtained with the center of mass of DCl fixed at various sites. These calculations were all performed based on an accurate potential energy surface recently constructed by neural network fitting to density function theory energy points. The origin of the extremely small dissociation probability for DCl/HCl (v=0, j=0) fixed at the top site compared to other fixed sites is elucidated in this study. The influence of vibrational excitation and rotational orientation of DCl on the reactivity was investigated by calculating six-dimensional dissociation probabilities. The vibrational excitation of DCl enhances the reactivity substantially and the helicopter orientation yields higher dissociation probability than the cartwheel orientation. The site-averaged dissociation probability over 25 fixed sites obtained from four-dimensional quantum dynamics calculations can accurately reproduce the six-dimensional dissociation probability.

Simultaneous Quantification of Hydride Ions and Electrons Incorporated in 12CaO·7Al2O3 Cages by Deuterium-Labeled Volumetric Analysis

An extended volumetric method, combined with quadrupole mass spectroscopy (QMS), is proposed. This method enables us to distinguish and simultaneously quantify hydride (H–) ions and electrons (e–) incorporated in cages of 12CaO·7Al2O3 (C12A7), which is accomplished upon annealing with CaH2. When a sample is dissolved in a deuterium chloride solution, most of the H– ions and electrons released from cages react to form HD and D2 molecules, respectively. These isotope-labeled molecules are then detected by QMS. We have used this method to follow the concentrations of H– ions and electrons in C12A7-treated CaH2 over the thermal treatment time. We found that during the initial seven days of treatment, both concentrations increased. Thereafter, the electron concentration begins to decrease, while the H– ion concentration continues to increase toward the theoretical maximum. This diverging behavior is due to differences in their diffusion ratios and thermodynamic stabilities.

Carrier envelope phase effects in photofragmentation: Orientation versus alignment

The optically induced fragmentation of deuterium chloride ions (DCl+) has been investigated by means of computer simulation within the Schrodinger wave-function formalism for three lowest 2gV electronic states coupled by IR-laser pulse with 34.6 fs duration. We demonstrate that the dependence of dissociation yields as function of the carrier envelope phase (CEP) of few-cycle laser pulses can be fundamentally different (2π or π periodicity) for oriented and aligned ions. To achieve a deep insight in mutual electronic nuclear dynamics we investigate the time dependence of fragmentation yields and vibrational populations as well as the space-time representation of electronic wave function probability dynamics for few selected cases. Ultimately we suggest an approach for distinguishing oriented from aligned molecular ensembles. Further-more the current concept provides access to directional product ion beams (D+ or/and Cl+) by proper selection of the CEP.

A Selective Preparation of Highly Deuterated Hydroxybenzoic Acids

A practical method to prepare selected deuterated hydroxybenzoic acids was developed. A hydroxybenzoic acid was dissolved or suspended in deuterium oxide (D2O), then deuterium chloride (DCl) was added to adjust the pD to 0.32, and the mixture was refluxed under nitrogen for one to six hours. After removing D2O and DCl by lyophilization, 2,6-dihydroxybenzoic-3,5-d2 acid, 3,5-dihydroxybenzoic-2,4,6-d3 acid, 3,5-dimethoxy-4-hydroxybezoic-2,6-d2 acid, and 3,4,5-trihydroxybenzoic-2,6-d2 acid were obtained quantitatively. Aromatic carbons with double substituent effects of hydroxy or methoxy groups were selectively deuterated. It was shown that the deuterium exchange reactions, which were electrophilic substitution reactions of deuterium cations to the aromatic carbons on the hydroxybenzoic acids, were regulated by the substituent effects. Deuteriums on all aromatic carbons were stable under a physiological condition and were detected in plasma by mass spectrometry analysis after oral administration to rats.

Investigating the Mechanism of Heteroaromatic Decarboxylation Using Solvent Kinetic Isotope Effects and Eyring Transition-State Theory

An upper-level mechanistic organic experiment is outlined where undergraduates measure kinetic rate constants for decarboxylation of pyrrole-2-carboxylic acid by the initial-rates method. UV spectroscopy is used to monitor reactant disappearance in both hydrochloric acid and deuterium chloride at different temperatures. Individual data are pooled and utilized by the class to calculate solvent kinetic isotope effects and reaction activation parameters (the latter from Eyring plots). Students interpret experimental results and additional literature data to deduce likely operative decarboxylation mechanisms at varying acidities.

Theoretical Investigations of Vibrational – Rotational Energy of some Hydrogen Halide Molecules

A theoretical study by using computer model is presented to study the energy characteristics of the vibrational – rotational levels as a function of the vibrational and rotational quantum number, respectively. The calculations were based on the basis of a multilevel model taking into account the non-equilibrium population of the rotational levels. The computational investigation has been performed to examine the vibrational-rotational characteristics of some hydrogen halides chemical laser molecules. This program takes into account the various molecules of chemical lasers such as, Hydrogen Fluoride (HF), Deuterium Fluoride (DF), Hydrogen Chloride (HCl), and Deuterium Chloride (DCl). The practical difficulties associated with this type of lasers suggested that alternative route might be quite useful. Thus particular attention was paid to the development of computer program to investigate various energy characteristics. Comparison of the calculated results for different molecules shows that the highest values for the HF molecule probably due to their higher constants in comparison with the other molecules.

Theoretical Investigations of Vibrational – Rotational Energy of some Hydrogen Halide Molecules

A theoretical study by using computer model is presented to study the energy characteristics of the vibrational – rotational levels as a function of the vibrational and rotational quantum number, respectively. The calculations were based on the basis of a multilevel model taking into account the non-equilibrium population of the rotational levels. The computational investigation has been performed to examine the vibrational-rotational characteristics of some hydrogen halides chemical laser molecules. This program takes into account the various molecules of chemical lasers such as, Hydrogen Fluoride (HF), Deuterium Fluoride (DF), Hydrogen Chloride (HCl), and Deuterium Chloride (DCl). The practical difficulties associated with this type of lasers suggested that alternative route might be quite useful. Thus particular attention was paid to the development of computer program to investigate various energy characteristics. Comparison of the calculated results for different molecules shows that the highest values for the HF molecule probably due to their higher constants in comparison with the other molecules.

Laser pulse control of photofragmentation in DCl +: The effect of carrier envelope phase

The optically induced fragmentation of deuterium chloride ions (DCl +) has been investigated by solving coupled time dependent Schrödinger equations. We demonstrate that the branching ratio D +:Cl + of competing reaction channels leading to either D + or Cl + can be controlled by up to a factor of 100 by means of the carrier envelope phase (CEP). This CEP effect depends on the wavelength, the intensity and on the chirp of the fs laser pulses.

On the Competition between Predissociation and Direct Dissociation in Deuterium Chloride Ions (DCl(+)).

The competition between direct dissociation and predissociation in DCl(+) ions prepared in the A(2)Σ(+) state has been investigated numerically by solving the time dependent Schrödinger equation. This work concentrates on the rovibronic states (vA;NA) with vA = 8 and NA = 60-65, which are close to the top of a centrifugal barrier. We find that the relative yield of D(+) (by direct dissociation) and Cl(+) (by predissociation) strongly depends on the excitation frequency, intensity, and duration. Investigation of the time dependence of the product yields provides evidence for significant multichannel interactions.

Foil cycling technique for the VESUVIO spectrometer operating in the resonance detector configuration

This article reports a novel experimental technique, namely, the foil cycling technique, developed on the VESUVIO spectrometer (ISIS spallation source) operating in the resonance detector configuration. It is shown that with a proper use of two foils of the same neutron absorbing material it is possible, in a double energy analysis process, to narrow the width of the instrumental resolution of a spectrometer operating in the resonance detector configuration and to achieve an effective subtraction of the neutron and gamma backgrounds. Preliminary experimental results, obtained from deep inelastic neutron scattering measurements on lead, zirconium hydride, and deuterium chloride samples, are presented.

Control of Branching Ratios in the Dissociative Ionization of Deuterium Chloride

The dissociative ionization of deuterium chloride (DCl) has been investigated by employing femtosecond laser pulses at 805 nm. The product branching ratio D(+)/Cl(+) of the fragments D(+) and Cl(+) is strongly affected by the chirp alpha of the laser pulses. The ratio can be controlled by a factor of 3 ranging from D(+)/Cl(+) = 0.7 at alpha = -800 fs(2) to D(+)/Cl(+) = 1.9 at alpha = +150 fs(2). The observation can be rationalized by a model where negative chirp favors intra-electronic state excitation, and positive chirp favors inter-electronic state excitation in the dissociation of the molecular ion. Complementary experiments on hydrogen chloride (HCl) are discussed.