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Using solid-state molecular organometallic (SMOM) techniques, in particular solid/gas single-crystal to single-crystal reactivity, a series of σ-alkane complexes of the general formula [Rh(Cy2PCH2CH2PCy2)(ηn:ηm-alkane)][BArF4] have been prepared (alkane = propane, 2-methylbutane, hexane, 3-methylpentane; ArF = 3,5-(CF3)2C6H3). These new complexes have been characterized using single crystal X-ray diffraction, solid-state NMR spectroscopy and DFT computational techniques and present a variety of Rh(I)···H–C binding motifs at the metal coordination site: 1,2-η2:η2 (2-methylbutane), 1,3-η2:η2 (propane), 2,4-η2:η2 (hexane), and 1,4-η1:η2 (3-methylpentane). For the linear alkanes propane and hexane, some additional Rh(I)···H–C interactions with the geminal C–H bonds are also evident. The stability of these complexes with respect to alkane loss in the solid state varies with the identity of the alkane: from propane that decomposes rapidly at 295 K to 2-methylbutane that is stable and instead undergoes an acceptorless dehydrogenation to form a bound alkene complex. In each case the alkane sits in a binding pocket defined by the {Rh(Cy2PCH2CH2PCy2)}+ fragment and the surrounding array of [BArF4]− anions. For the propane complex, a small alkane binding energy, driven in part by a lack of stabilizing short contacts with the surrounding anions, correlates with the fleeting stability of this species. 2-Methylbutane forms more short contacts within the binding pocket, and as a result the complex is considerably more stable. However, the complex of the larger 3-methylpentane ligand shows lower stability. Empirically, there therefore appears to be an optimal fit between the size and shape of the alkane and overall stability. Such observations are related to guest/host interactions in solution supramolecular chemistry and the holistic role of 1°, 2°, and 3° environments in metalloenzymes.

A novel ZIF-8-CMC hybrid material was fabricated from the hybridization of ZIF-8 and carboxymethylcellulose (CMC) by impregnation method for n-hexane/3-methylpentane separation. The surface properties of ZIF-8 were tailored by introducing CMC into ZIF-8 nanoparticles. In this work, adsorption separation of n-hexane (nHEX) and 3-methylpentane (3MP) on ZIF-8-CMC were investigated by batch vapor-phase adsorption and liquid-phase breakthrough adsorption. The adsorption selectivity of nHEX/3MP reversed from preferable adsorption of nHEX to preferable adsorption of 3MP upon the increasing of CMC containing in the hybrid materials. As the temperature increases, the adsorption amounts of nHEX and 3MP decrease. With the increasing of CMC contents, the nHEX uptake decreased, the uptake capacity of 3MP increased gradually. For liquid-phase breakthrough adsorption, the dynamic adsorption capacity of nHEX also decreased with the increasing of temperature.

In this work, we present densities at high pressures of three branched hydrocarbons: 3-methylpentane, 2,4-dimethylpentane, and 2,3,4-trimethylpentane from 283.15 to 363.15 K and at pressures up to ...

The isothermal vapour-liquid equilibria of R-23 + 1-hexene, R-23 + 3-methylpentane, R-116 + 1-hexene and R-116 + 3-methylpentane were measured at temperatures of between (293.1 and 313.3) K with a static-analytic apparatus. Vapour-liquid-liquid equilibria was exhibited by the R-116 + 1-hexene system. The equilibrium data was modelled with the PR EOS, modified with the MC alpha function, and the WS mixing rule with either the NRTL or the UNIQUAC activity coefficient model. Both the temperature dependent and the temperature independent forms of the models were regressed to the experimental data. The method of Ungerer et al. was used to extrapolate the subcritical co-existence data to the mixture critical loci, while the method of Heidemann and Khalil was used to estimate the critical locus curves for the systems. Each of the four systems were also categorised according to the classification system of van Konynenburg and Scott.

Equations of state for three hexane isomers, 3-methylpentane, 2,2-dimethylbutane, and 2,3-dimethylbutane, have been developed based on experimental thermodynamic property data from the literature. These equations are explicit in the Helmholtz energy with independent variables of temperature and density. The temperature, pressure, and density validity ranges of the equations of state were determined by the available measured data for these three fluids. The uncertainties in densities, vapor pressures, saturated liquid and vapor densities, and caloric properties were estimated by comparisons with experimental data of these properties. The behavior of various thermodynamic properties was analyzed to assess the quality of the equations of state. Physically correct behavior within the region of validity and at extremely high temperatures and pressures, and temperatures far below the triple-point temperature, was obtained through fitting multiple constraints of various properties.

3-Methylpentane (C6H14, CAS No. 96-14-0), isomer of hexane, is a colorless liquid originating naturally from petroleum or natural gas liquids. 3-Methylpentane has been used as a solvent in organic synthesis, as a lubricant, and as a raw material for producing carbon black. There is limited information available on the inhalation toxicity of 3-methylpentane, and the aim of this study was to determine its subacute inhalation toxicity. According to OECD Test Guideline 412 (subacute inhalation toxicity: 28-day study), Sprague Dawley rats were exposed to 0, 284, 1,135, and 4,540 ppm of 3-methylpentane for 6 hr/day, 5 days/week for 4 weeks via whole-body inhalation. Mortality, clinical signs, body weights, food consumption, hematology, serum chemistry, organ weights, and gross and histopathological findings were compared between control and all exposure groups. No mortality or remarkable clinical signs were observed during the study. No gross or histopathological lesions, or adverse effects on body weight, food consumption, hematology, serum chemistry, and organ weights were observed in any male or female rats in all exposure groups, although some statistically significant changes were observed in food consumption, serum chemistry, and organ weights. In conclusion, the results of this study indicate that no observable adverse effect level (NOAEL) for 3-methylpentane above 4,540 ppm/6 hr/day, 5 days/week for rats.

Consistent vapor–liquid equilibrium (VLE) data for the ternary systems 3-methylpentane + ethanol + methylcyclohexane and ethanol + tert-butyl alcohol (TBA) + methylcyclohexane are reported at 101.3 kPa. The VLE data have been correlated by Wilson, UNIQUAC and NRTL equations. The ternary systems do not present azeotrope and are well predicted from binary interaction parameters.

Although abundant literature data are available on liquid–liquid phase equilibrium for select hydrocarbon–water systems at ambient or near ambient temperatures, a deficiency exists for data at elevated temperatures. In this study, we sought to (a) evaluate existing mutual hydrocarbon–water liquid–liquid equilibrium (LLE) data, (b) develop an experimental apparatus capable of measuring accurately the hydrocarbon–water (LLE) mutual solubilities, and (c) perform measurements on the benzene–water, toluene–water, and 3-methylpentane–water systems. A continuous flow apparatus was utilized to measure the LLE mutual solubilities at temperatures ranging from ambient to 500 K, which is near the three-phase critical end point of the benzene–water and toluene–water systems. The well-documented benzene–water system was used to validate the reliability of the sampling and analytical techniques employed. Generally, the present measurements showed adequate agreement with available literature data. An error propagation an...

The isomerization on sulphated zirconias of the 3-methyl(3-13C)pentane, molecule chosen to distinguish between the methyl and ethyl migrations, is studied. The products distribution shows 0% for the 3-methylpentane isotopomers (not detected? or not formed?), what makes the interpretations difficult. Supposing these molecules formed in low proportions but not detected, a reaction pathway involving protonated cyclopropanes is proposed: the isotopomers are obtained from one- two- or three-step reactions. However, it is envisaged the possible non-formation of these molecules and a reaction pathway involving protonated cyclopropanes, cyclobutanes and bicyclopropanes is suggested: the 13C-label scrambling would be a two-step isomerization and the other isotopomers would be formed via a one-step reaction. The relative proportions of methyl migration (MM) and ethyl migration (EM) are assessed. The MM/EM ratio could be appreciated as an intrinsic characteristic of the catalyst because of correlations with, e.g. the crystalline structure, the sulphate content and the activity. Such correlations knowledge could help preparing catalysts with high activity and selective reactivity.

A new flexible ligand, 1,5-bis(8-oxaquinoline)-3-methylpentane (C5MeOQ), was synthesized and used in the preparation of the new dinuclear copper(II) complex 1: [Cu2(μ-OMe)2(μ-C5MeOQ)(NO3)2]. Single crystal X-ray analysis revealed that complex 1 contains dinuclear Cu(II) units with bridging methoxo groups. The ligand, C5MeOQ, takes on a bent conformation in order to connect to and complete the square planar coordination environment of both copper centers; and one of the two Cu(II) centers adopts a distorted square planar configuration as a result of the ligand conformation. The magnetic properties of complex 1 were investigated by variable-temperature magnetic susceptibility measurements in the 100–300 K range. Interestingly, the susceptibility data for complex 1 reveals that the compound is diamagnetic, suggesting the presence of very strong antiferromagnetic coupling interactions between the adjacent Cu(II) centers.

Excess molar enthalpies, measured at 298.15 K in a flow microcalorimeter, are reported for the two ternary mixtures formed by mixing either methyl tert-butyl ether with binary mixtures of 3-methylpentane and either n-decane or n-dodecane. Smooth representations of the ternary results are presented and used to construct constant excess molar enthalpy contours on Roozeboom diagrams. It is found that the Liebermann and Fried model also provided good representation of the ternary results, using only the physical properties of the components and their binary mixtures.

Microcalorimetric measurements of excess molar enthalpies, at 298.15 K, are reported for the two ternary systems formed by mixing either diisopropyl ether or tetrahydrofuran with binary mixtures of 3-methylpentane and n-dodecane. Smooth representations of the results are presented and used to construct constant excess molar enthalpy contours on Roozeboom diagrams. It is shown that useful estimates of the ternary enthalpies can be obtained from the Liebermann and Fried model, using only the physical properties of the components and their binary mixtures.

The photokinetic behaviour of 5,6-benzo(2H)dimethylchromene was investigated in 3-methylpentane solution by spectrophotometric methods using monochromatic irradiation wavelengths in the UV and visible regions. This molecule only exhibits photochromism at low temperature (T240 K), since the rate of the back thermal reaction (bleaching) is very fast (k10(2) s(-1)) at ambient temperature. The colour-forming kinetics were followed under continuous irradiation using UV light (318 nm) in two low temperature ranges (160-140 and 235-219 K). In the 160-140 K interval, the temperature is low enough to reduce the thermally activated processes and UV irradiation produces one coloured form, C1 (phi(C1) = 0.42). Visible light irradiation converts C1 (phi(-C1) = 0.10) to a photoproduct, P, which is thermally and photochemically stable in that temperature range. In the 235-219 K temperature interval, both thermal and photochemical processes were detected: two coloured forms, C1 and C2, are produced in consecutive steps, one of them is thermoreversible, whereas the other is photoreversible. Quantum yields of the photoreactions and kinetic parameters (rate coefficient and activation energy) of the thermal ring-closure reaction were determined. Based on the results obtained, a plausible reaction mechanism is proposed.

The influence of the loading on the self-diffusion of 3-methylpentane within silicalite-1 has been studied with Positron Emission Profiling technique. A monotonous decrease in the self-diffusivities of alkane was observed with zeolite loading, which could be approximated by a stretched exponential. As a consequence, the apparent activation energy increases with partial pressure.

Measurements of excess molar enthalpies at the temperature 298.15 K in a flow microcalorimeter, are reported for the two ternary mixtures { X 1 C 4 H 8 O + X 2 CH 3 CH 2 CH(CH 3 )CH 2 CH 3 + (1− X 1 − X 2 )CH 3 (CH 2 ) v −2 CH 3 } with v =8 and 10. Smooth representations of the results are described and used to construct constant-enthalpy contours on Roozeboom diagrams. It is shown that useful estimates of the ternary enthalpies can be obtained from the Liebermann–Fried model, using only the physical properties of the components and their binary mixtures.

Measurements of excess molar enthalpies at 25°C in a flow microcalorimeter are reported for the two ternary mixtures 2-methyltetrahydrofuran + 3-methylpentane + n-decane and di-n-butyl ether + 3-methylpentane + n-decane. Smooth representations of the results are described and used to construct constant-enthalpy contours on Roozeboom diagrams. It is shown that useful estimates of the ternary enthalpies can be obtained from the Liebermann–Fried model using only the physical properties of the components and their binary mixtures.

Excess molar enthalpies, measured at 298.15 K in a flow microcalorimeter, are reported for diisopropyl ether + 3-methylpentane + octane and for diisopropyl ether + 3-methylpentane + decane. Smooth representations of the results are described and used to construct constant excess molar enthalpy contours on Roozeboom diagrams. The latter are compared with diagrams obtained when the model of Liebermann and Fried is used to estimate the excess molar enthalpies of the ternary mixtures from the physical properties of the components and the excess molar enthalpies of their constituent binary mixtures.

The reactivity of 3-methylpentane (3MP) and hexane (H) on HZSM-5 at 120–160 °C changes from gas (H > 3MP) to liquid phase (3MP > H), as does product selectivity. The liquid phase reactivity ratio is similar on HZSM-5 and in trifluoromethanesulfonic acid (TFMSA), where the reaction involves initiation by oxidation to allyl cations. In both cases, olefins are intermediates, but do not appear in the products. Because hydride transfer catalysis is absent in the reaction of H and the steric requirements for hydride transfer are smaller than for cracking, the mechanism involving protonation of sigma bonds, as in liquid superacids, does not operate in zeolites. The H:3MP reactivity ratio does not measure steric constraints in cavities.

Consistent vapor–liquid equilibria (VLE) at 101.3 kPa has been determined for the ternary system 3-methylpentane+diisopropyl ether (DIPE)+methylcyclohexane and the binary subsystems 3-methylpentane+methylcyclohexane and DIPE+methylcyclohexane in the temperature range from 336 to 374 K. According to the experimental results, the systems exhibit slight positive deviation from ideal behavior and no azeotrope is present. The VLE data have been correlated with the composition using the Wilson, UNIQUAC and NRTL relations. These models allow good prediction of the VLE properties of the ternary system from those of the pertinent binary subsystems.

This article has no abstract. Keywords: 2-methylpentane; isohexane; 3-methylpentane; 2,2-dimethylbutane; neohexane; 2,3-dimethylbutane; gas chromatography; GC; double capillary technique; adsorption on charcoal; workplace measurement; air analysis; occupational monitoring; analytical method; hazardous substance; measurement procedure; expanded uncertainty; personal sampling; stationary sampling

Isothermal vapor−liquid equilibrium data were measured for two binary systems, 3-methylpentane + 2-methyl-2-propanol at 331 K and 3-methylpentane + 2-butanol at 331 K. The measurements were made with a recirculation still. The results were correlated with the Soave−Redlich−Kwong equation of state and the Wilson activity coefficient model.

Isobaric vapor−liquid equilibria data were obtained for the 3-methylpentane + 2-methyl-2-propanol binary system and methyl 1,1-dimethylethyl ether + 3-methylpentane + 2-methyl-2-propanol ternary system at 101.3 kPa in a temperature range from 329 to 356 K. The data were found to be thermodynamically consistent according to the Van Ness−Byer−Gibbs method for the binary system and according to the McDermott−Ellis method for the ternary one. The binary system shows a minimum boiling azeotrope that boils at 333.4 K and contains 82.6 mol % of 3-methylpentane. The binary interaction parameters obtained from this work and literature data are used to predict the vapor−liquid equilibrium for the ternary system using the UNIQUAC, NRTL, and Wilson models. The ternary system is well predicted from binary data.

Pure-component vapor pressure of 3-methylpentane and vapor–liquid equilibrium (VLE) for the binary systems of 3-methylpentane with methyl 1,1-dimethylethyl ether (MTBE) and with methyl 1,1-dimethylpropyl ether (TAME) at 101.3 kPa have been measured. Both systems exhibit small positive deviations from ideality. They can be described as regular solutions and do not present azeotrope. The activity coefficients and boiling points of the solutions were correlated with its composition by Wilson, UNIQUAC, NRTL, and Wisniak–Tamir equations.

Photochemical properties of the lowest triplet state of 4H-1-benzopyran-4-thione (BPT) in 3-methylpentane were studied in the thione concentration range 10−7 − 10−3 M. The quantum yield of the photochemical decomposition of BPT was found to be highly concentration dependent. For low BPT concentrations ( 10−4 M, the BPT triplet decays almost entirely in a self-quenching process. HPLC analysis showed that five different photoproducts, including an oligomer, are formed. Knowledge of earlier studied photophysical properties of BPT in 3-methylpentane and perfluoroalkanes permitted a quantitative explanation of the mechanism of photochemical reactions of 3(BPT). The studies indicate, for BPT concentrations

The enthalpies of solution at infinite dilution of 2-chloro-2-methylpropane in 9 dialcohols and of 2-chloro-2-methylbutane and 3-chloro-3-methylpentane in 19 mono- and dialcohols, at 298.15 K, were measured using a solution calorimeter. These values are discussed in terms of solute-solvent interactions. Together with previous data, this information provides a thermodynamic picture of the effect of the size of the alkyl chlorides and the structure of the alcohols.

A circular (CD) and linear dichroism (LD) study of the water adducts of the green plant chlorophylls a (Chl a) and b (Chl b) in hydrocarbon solvents 3-methylpentane and paraffin oil is presented. A strong red shift of the Qy-absorption band from 663 to 746 nm (1678 cm−1) is observed as the water adduct of Chl a is formed. The Chl a-water adduct shows a strong, nonconservative CD signal, which is characterized by a positive peak at 748 nm and two negative peaks at 720 and 771 nm. The maximum CD (AL - AR) is only one order of magnitude smaller than the isotropic absorption maximum. We propose that this exceptionally strong signal is the so-called psi-type CD. The LD spectrum was measured in a flow of paraffin oil. The isotropic absorption maximum peaks at 742 nm in paraffin oil, whereas the maximum of the LD signal is at 743 nm. The LD signal is positive over the whole water-adduct absorption band indicating that the transition dipole of the 742 nm transition is preferentially oriented along the long axis of the aggregate. The structure of the Chl b-water adduct is less well defined. The preparations of the Chl b-water adduct are unstable. The Chl b-water adduct absorption band maximum is at 683 nm. The CD signal of the Chl a-water adduct is about 200-fold the CD of the Chl b-water adduct. We could not orient the Chl b-water adducts by flow, which suggests that the adducts are small or disordered.

The structural relaxations of 3-methylpentane and 1-propanol have been investigated around their glass transition temperatures at several constant pressures between 0 and 200 MPa. The structural relaxation was observed as a temperature evolution due to the enthalpy relaxation by using a high-pressure adiabatic calorimeter. The initial states for the relaxations (glassy states) were prepared through two different paths on the pressure-temperature plane; one was a rapid cooling at constant pressure (temperature jump: TJ) and the other a rapid pressurization at nearly constant temperature (pressure jump: PJ). It was found that both of the relaxation processes of the PJ and TJ glasses were quite non-exponential. The relaxation function of the PJ glass was different from that of the TJ glass. The relaxations for the TJ experiments were well analyzed in terms of the Adam-Gibbs (entropy) theory in the entire pressure and temperature regions investigated.

Vapour pressures of n -butanol with 2-methylpentane and 3-methylpentane between 283.15 and 313.15 K were measured at 5 K intervals by a static method. Excess enthalpies and excess volumes, at 298.15 K, were also measured. Experimental excess volumes are compared with predictions of an extended real associated solution (ERAS) model. The model reproduces qualitatively the experimental curves of V E and gives a good description of the experimental results of G E at 298.15 K.

The fluorescence properties of 4-methyl-2,6-diacetylphenol (MAOH) are examined in 3-methylpentane and quantum yield measurements are made at room temperature and 77 K. The fluorescence quantum yield is temperature and excitation wavelength dependent. The emission properties of MAOH at 77 K have been examined in relation to those of 4-methyl-2,6-diformylphenol (MFOH). At this temperature, unlike MFOH, MAOH does not show any phosphorescence in 3-methylpentane. From this observation it is confirmed that phosphorescence appears due to the rotation of the formyl group in MFOH. The fluorescence decay rate of MAOH is relatively faster than that of MFOH and non-radiative decays are dominant in the decay processes of the excited states of both compounds.

Static viscosity measurements of two mixtures of 3-bromopentane in 3-methylpentane are presented in the temperature range from 94 to 112 K and over a range of viscosities from 3 × 107 to 280 Pa s. The data are fitted to the Vogel-Fulcher-Tamman equation. Estimates of the glass transition temperatures for these mixtures based on the reference viscosity of 1 × 1012 Pa s are 90.1 and 98.8 K for 0.500 mole fraction and 0.750 mole fraction of 3-bromopentane in 3-methylpentane, respectively. Additionally, viscosity measurements on pure 3-methylpentane, previously reported, have been extended to higher temperatures. These viscosity values and those measured in this laboratory on 3-bromopentane, along with estimates of their glass transition temperatures, are also presented for comparison purposes.

The (vapour + liquid) equilibria of (3-methylpentane + heptane) at T = 308.15 K, 318.15 K, and 328.15 K; of (3-methylpentane + octane) at T = 338.15 K; and of (toluene + octane) at T = 333.15 K, have been obtained by using a dynamic still, and excess volumes of these mixtures have been measured at T = 298.15 K using an Anton-Paar densitometer. The VLE results were analysed by applying the maximum-likelihood principle and are well correlated by the Wilson, NRTL, and modified UNIQUAC equations. They are also compared satisfactorily with a group-contribution equation of state.

The heat capacities of 1-propanol and 3-methylpentane were measured in the temperature range 50–180 K (50–130 K for the latter) and at three different pressures (0, 108, 198 MPa) using an adiabatic high-pressure calorimeter. For both substances, the glassy state was readily realized by cooling the liquid and glass transitions were observed calorimetrically at every pressure. Thermodynamic quantities associated with the fusion of the crystalline phase were measured at three pressures for 1-propanol and at 108 MPa for 3-methlpentane. Pressure dependences of the glass transition and fusion were accurately determined. Experimental data for the entropy of fusion and the heat capacity difference between the glass and the liquid were combined to calculate the temperature dependence of the configurational entropy, Sc, at each pressure. The pressure dependence of the Kauzmann temperature, T0, at which Sc tends to vanish, was also determined. It was found that the quantity TSc was almost constant at Tg for respective pressures, indicating the validity of the entropy theory proposed by Adam and Gibbs.

Experimental time-average conversions and selectivities for reactions of 3-methylpentane and 2-methylpentane have been measured on USHY at 400[degrees]C to provide additional confirmation of the proposal that initiation of the cracking of saturated compounds takes place via the protolysis of a feed molecule and is always followed by some degree of conversion via a bimolecular, carbenium-ion-induced chain process. 11 refs., 4 tabs.

The H–D exchange of deuteriated Y zeolites, silica–alumina and γ-alumina with 3-methylpentane has been studied by IR spectroscopy. At 373 K exchange ocurred only in the zeolites. Silica–alumina required higher temperatures (523–623 K) and exchange did not occur in γ-alumina in the range of temperature studied. Ultrastable Y zeolite with non-framework alumina (NFA), showed a higher reactivity for H–D exchange and hexane cracking than Y zeolite dealuminated by (NH4)2SiF6. These findings were explained by the difference in acid strength between the zeolites, probably due to the presence of NFA as proposed in the literature, and stress the dependence of H–D exchange on acid strength. The IR study of H–D exchange between 3-methylpentane and Y zeolites having pyridine pre-adsorbed, neutralizing some of the hydroxy groups, showed that the high-frequency (hf) hydroxy group is responsible for the exchange. The low-frequency (If) and NFA hydroxy groups appear to exchange via hydrogen bridges with the hf hydroxy group, rather than by direct interaction with the hydrocarbon. The H–D exchange between solid acids and alkanes could be a qualitative test for acid strength, since only very strong acids would attack σ bonds.

The standard ( p o = 0.1 MPa) molar enthalpy of formation of the crystalline complex of iron(III) with 3-methylpentane-2,4-dione (HMe acac ) was determined at the temperature 298.15 K, by solution-reaction calorimetry as −(1360.3 ± 5.8) kJ · mol −1 . The enthalpy of sublimation at the temperature 298.15 K, determined by microcalorimetry, was found to be (164.5 ± 2.8) kJ · mol −1 . From the standard molar enthalpy of formation of the gaseous complex, the mean molar bond-dissociation enthalpy, 〈 D m 〉(Fe-O), was derived as (172 ± 11) kJ · mol −1 .

The standard ( p o = 0.1 MPa) molar enthalpy of combustion in oxygen at 298.15 K of liquid 3-methylpentane-2,4-dione (HMe acac ) was measured by static bomb calorimetry as −(3353.2±1.7) kJ · mol −1 . The standard molar enthalpy of formation of the crystalline copper(II) complex with 3-methylpentane-2,4-dione was determined, at the temperature 298.15 K, by solution-reaction calorimetry. The vapour pressures of the complex were measured as function of temperature by the Knudsen-effusion technique, and the standard molar enthalpy of sublimation Δ g cr H o m (396.70 K)/(kJ · mol −1 ) = 130.7 ± 1.0, was derived by the Clausius-Clapeyron equation. From this value, the standard molar enthalpy of sublimation was calculated as Δ g cr H o m (298.15 K)/(kJ · mol −1 ) = 135.6 ± 1.0. Measurement of the standard molar enthalpy of sublimation using a direct microcalorimetric method, confirmed the value from the Knudsen technique.