Physical Properties of 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (mTBD)

Abstract

7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (mTBD) has useful catalytic properties and can form an ionic liquid when mixed with an acid. Despite its potential usefulness, no data on its thermodynamic and transport properties are currently available in the literature. Here we present the first reliable public data on the liquid vapor pressure (temperature from 318.23 K to 451.2 K and pressure from 11.1 Pa to 10 000 Pa), liquid compressed density (293.15 K to 473.15 K and 0.092 MPa to 15.788 MPa), liquid isobaric heat capacity (312.48 K to 391.50 K), melting properties, liquid thermal conductivity (299.0 K to 372.9 K), liquid refractive index (293.15 K to 343.15 K), liquid viscosity (290.79 K to 363.00 K), liquid-vapor enthalpy of vaporization (318.23 K to 451.2 K), liquid thermal expansion coefficient (293.15 K to 473.15 K), and liquid isothermal compressibility of mTBD (293.15 K to 473.15). The properties of mTBD were compared with those of other relevant compounds, including 1,5-diazabicyclo(4.3.0)non-5-ene (DBN), 1,8-diazabicyclo[5.4.0]undec-7ene (DBU), and 1,1,3,3-tetramethylguanidine (TMG). We used the PC-SAFT equation of state to model the thermodynamic properties of mTBD, DBN, DBU, and TMG. The PC-SAFT parameters were optimized using experimental data.

Vapor Pressures, Densities, and PC-SAFT Parameters for 11 Bio-compounds

“…Our data falls in line with the literature data, although it has a somewhat larger scatter than some of the literature data sets. In more recent experiments with the gas saturation equipment, we were able to improve the repeatability by making repeat measurements of the cell mass and taking the average of them, [75] so it seems that uncertainty in the sample weight was the largest contribution to the uncertainty for the gas saturation measurements presented here. We did not observe any systematic bias in our data when compared to the model or other data.…”

Densities, Viscosities, and Thermal Conductivities of the Ionic Liquid 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium Acetate and Its Mixtures with Water

“…The first sample of 7-methyl-1,5,7-triazabicyclo [4.4.0]dec-5-ene (mTBD) was synthesized and purified at the University of Helsinki. A second sample was purchased from BOC Sciences, and later this was further purified via distillation (see the description in our earlier article [13]). Two samples of acetic acid were also used.…”

“…The gas chromatograph had a flame ionization detector, and because water does not give a signal with this detector the water content from Karl Fischer titration was taken into account when calculating the purity. The purity of the mTBD was determined using a capillary electrophoresis method described in our earlier article [13].…”

“…After further analyzing the data from the purity analysis, it was found that the actual purity was only 97.2 wt%, and that the mTBD also contained 1.6 wt% of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as an impurity. To see how much the impurities affected the density and viscosity, measurements for the mTBD from BOC Sciences were compared to earlier measurements we had performed with mTBD synthesized at the University of Helsinki [13]. No difference could be detected in the viscosity data, and so the influence of these impurities could be neglected for the viscosity measurements.…”

“…The mTBD was purified via distillation, as described in our earlier article [13]. This was done using a 0.55 m Vigreux column and a reflux ratio of 3:8.…”