I. INTRODUCTION
Methoxetamine, MXE [2-(ethylamino)-2-(3-methoxyphenyl)cyclohexan-1-one] is a structural and pharmacological analog of ketamine (Morris and Wallach, Reference Morris and Wallach2014). For the first time it was synthetized in the UK by a synthetic chemist known as “M”. Structurally MXE belongs to the group of arylcyclohexylamines and has anesthetic and sedative effects (Zanda et al., Reference Zanda, Fadda, Chiamulera, Fratta and Fattore2016). This designer drug emerged on the black market in 2010 and by 2015 was involved in 120 non-fatal and 22 fatal intoxications (EMCDDA, 2014; Zanda et al., Reference Zanda, Fadda, Chiamulera, Fratta and Fattore2016). Though important pharmacological data have been published (e.g. metabolism, behavioral tests), there is still the lack of information about this compound (Menzies et al., Reference Menzies, Hudson, Dargan, Parkin, Wood and Kicman2014; Zawilska, Reference Zawilska2014; Hajkova et al., Reference Hajkova, Jurasek, Sykora, Palenicek, Miksatkova and Kuchar2016; Horsley et al., Reference Horsley, Lhotkova, Hajkova, Jurasek, Kuchar and Palenicek2016; Zanda et al., Reference Zanda, Fadda, Chiamulera, Fratta and Fattore2016). MXE had been offered as the legal alternative for ketamine, but because of the dozens of severe intoxications it was banned in most EU states (Jurasek and Kuchar, Reference Jurasek and Kuchar2016; Zanda et al., Reference Zanda, Fadda, Chiamulera, Fratta and Fattore2016). Even though MXE (Figure 1) is banned by law, its analogs are available on the black market and may be still legal (e.g. methoxphenidine and deschloroketamine) (Hofer et al., Reference Hofer, Degrandi, Müller, Zürrer-Härdi, Wahl, Rauber-Lüthy and Ceschi2014; Frison et al., Reference Frison, Zamengo, Zancanaro, Tisato and Traldi2016).
Figure 1. Structural formula of 2-(ethylamino)-2-(3-methoxyphenyl)cyclohexan-1-one hydrochloride.
We have not found this compound in the CSD database or in the PDF4+ database (Allen, Reference Allen2002; ICDD, 2015). Therefore, we have decided to characterize this compound by X-ray powder diffraction (XRD) technique. In our study, we present powder data for MXE hydrochloride (C15H22ClNO2).
II. EXPERIMENTAL
A. Synthesis
The synthesis of MXE hydrochloride was carried out according to Hays et al. (Reference Hays, Casale and Berrier2012) instructions and Stevens and Parke (Reference Stevens and Parke1966) patent. 1-((Ethylimino)(3-methoxyphenyl)methyl)cyclopentan-1-ol (600 mg, 2.4 mmol) was dissolved in decalin (2 ml) and stirred 15 h at 190 °C in a microwave reactor. The reaction mixture was cooled, diluted with 15% hydrochloric acid, and extracted with dichloromethane. The aqueous layer was separated, and then it was made alkaline and extracted with diethyl ether. The organic layer was dried over MgSO4 and suction filtered. The filtrate was treated with a solution of hydrogen chloride in diethyl ether and the solvent was evaporated. Further purification was done by recrystallization from isopropyl alcohol. MXE hydrochloride was isolated as a yellowish solid and confirmed by NMR (nuclear magnetic resonance) analysis (130 mg, 19% yield) (Stevens and Parke, Reference Stevens and Parke1966; Hays et al., Reference Hays, Casale and Berrier2012).
B. Specimen preparation
The sample was prepared by careful grinding in an agate mortar and was then front-loaded into the specimen holder.
C. Diffraction data collection and reduction
The diffraction pattern for the title compound was collected at room temperature with an X'Pert3 Powder θ–θ powder diffractometer with parafocusing Bragg–Brentano geometry using CuKα radiation (λ = 1.5418 Å, Ni filter, generator setting: 40 kV, 30 mA). An ultrafast PIXCEL detector was employed to collect XRD data over the angular range from 5 to 70° 2θ with a step size of 0.013° 2θ and a counting time of 316.97 s step−1.
The software package HighScore Plus V 3.0e (PANalytical, Almelo, The Netherlands) was used to smooth the data, to fit the background, to eliminate the K α 2 component, and the top of the smoothed peaks were used to determine the peak positions and intensities of the diffraction peaks (Table 1). The d-values were calculated using CuK α 1 radiation (λ = 1.5406 Å).
TABLE I. Indexed X-ray powder diffraction data for C15H22ClNO2.
Only the peaks with I rel of 1 or greater are presented [a = 8.574(2) Å, b = 9.943(2) Å, c = 8.774(1) Å, β = 100.294(3)°, unit-cell volume V = 736(1) Å3, Z = 2, and space-group P21]. All lines were indexed and are consistent with the P21 space group. The d-values were calculated using CuK α 1 radiation (λ = 1.5406 Å).
III. RESULTS AND DISCUSSION
The automatic indexing of results was obtained using TREOR (Werner et al., Reference Werner, Erikson and Westdahl1985). The experimental powder diffraction pattern is showed in Figure 2. MXE hydrochloride, C15H22ClNO2, is monoclinic with space group P21 and unit-cell parameters: a = 8.574(2) Å, b = 9.943(2) Å, c = 8.774(1) Å, β = 100.294(3)°, unit-cell volume V = 736(1) Å3, and Z = 2. The figures of merits are F 20 = 45(0.0161, 28) and M 20 = 22 (de Wolff, Reference de Wolff1968; Smith and Snyder, Reference Smith and Snyder1979). All measured lines (Table 1) were indexed and are consistent with the P21 space group.
Figure 2. X-ray powder diffraction pattern of title compound using CuK α radiation (λ = 1.5418 Å).
The single-crystal experiment was done at the temperature of 190 K and the structure solution was obtained. The title compound is monoclinic with space group P21 and unit-cell parameters: a = 8.5360(7) Å, b = 9.9155(9) Å, c = 8.7558(8) Å, β = 100.354(2)°, unit-cell volume V = 729.0(7) Å3, and Z = 2. The difference in unit-cell parameters from the single-crystal data and the powder diffraction data is because of the temperature expansion.
SUPPLEMENTARY MATERIAL
The supplementary material for this article can be found at https://doi.org/10.1017/S0885715617000860.
Acknowledgements
Financial support from specific university research (MSMT No 20-SVV/2017) and by the Ministry of Interior of the Czech Republic (MV0/VI20172020056).
