title: GC-MS and FTIR evaluation of the six benzoyl-substituted-1-pentylindoles: isomeric synthetic cannabinoids.
abstract: This report compares the GC-MS and FTIR properties of all 6 regioisomeric benzoyl substituted-1-n-pentylindoles. These compounds have the benzoyl-group attached at each of the possible ring substituent positions of the indole ring. The six compounds have the same elemental composition C20H21NO yielding identical nominal and exact masses. Additionally, the substituents attached to the indole ring, benzoyl- and 1-n-pentyl-groups, are identical for all six isomers. The electron ionization mass spectra show equivalent regioisomeric major fragments resulting from cleavage of the groups attached to the central indole nucleus. Fragment ions occur at m/z 77 and 105 for the phenyl and benzoyl cations common to all six regioisomeric substances. Fragmentation of the benzoyl and/or pentyl groups yields the cations at m/z 234, 220, 214, 186 and 144. While the relative abundance of the ions varies among the six regioisomeric substances the 1-n-pentyl-3-benzoylindole and 1-n-pentyl-5-benzoylindole share very similar relative abundances for the major fragment ions. Chromatographic separations on a capillary column containing a 0.5μm film of 100% trifluoropropyl methyl polysiloxane (Rtx-200) provided excellent resolution of these six compounds. The elution order appears related to the relative distance between the two indole substituted groups. The latest eluting compounds (highest retention time) have the two substituents on opposite sides of the indole nucleus. Infrared absorption spectral data show the carbonyl absorption band for each of the benzoylindoles and provide distinguishing and characteristic information to individualize each of the regioisomers in this set of compounds.
authors.affiliation: Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, United States.
authors.forename: Forrest T
authors.initials: FT
authors.lastname: Smith
authors.affiliation: Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, United States.
authors.forename: Jack
authors.initials: J
authors.lastname: DeRuiter
authors.affiliation: Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, United States; Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Alexandria University, Alexandria 21521, Egypt.
authors.forename: Karim
authors.initials: K
authors.lastname: Abdel-Hay
authors.affiliation: Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, United States. Electronic address: clarkcr@auburn.edu.
authors.forename: C Randall
authors.initials: CR
authors.lastname: Clark
mesh_terms: D000447:Aldehydes / Q000737:chemistry; D002186:Cannabinoids / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical / Q000379:methods; D002845:Chromatography / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D007211:Indoles / Q000737:chemistry*; D007477:Ions; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013237:Stereoisomerism
chemical_list: D000447:Aldehydes; D002186:Cannabinoids; D007211:Indoles; D007477:Ions
keywords: Forensic chemistry; GC–MS; Indole derivatives; Regioisomers; Synthetic cannabinoids