GC-MS and GC-IR analysis of regioisomeric cannabinoids related to 1-(5-fluoropentyl)-3-(1-naphthoyl)-indole

• NCJ Number: 253203
• Journal: Forensic Chemistry Volume: 10 Dated: August 2018 Pages: 48-57
• Author(s): Jack DeRuiter; Forrest Smith; Younis Abiedalla; Logan Neal; C. Randall Clark
• Date Published: August 2018
• Length: 10 pages
• Grant Number(s): 2012-DN-BX-K026
• Agencies: NIJ-Sponsored
• Publication Type: Research (Applied/Empirical); Report (Study/Research); Report (Grant Sponsored); Program/Project Description
• Award: Forensic Chemistry of Substituted 1-Alkyl-3-Acylindoles: Isomeric Synthetic Cannabinoids.

Annotation

This study compared the analytical properties of six indole derivatives.

Abstract

The compounds in this study were the regioisomeric 2-, 3-, 4-, 5-, 6- and 7-(1-naphthoyl) substituted 1-(5-fluoropentyl)-indoles and the 3-(1-naphthoyl) substituted isomer in this series is also known as AM-2201. These compounds are structurally similar to JWH-018 except for the additional fluorine at the terminal end of the n-pentyl side-chain. These six regioisomeric compounds have the identical elemental composition (C24H22FNO) and differ in the position of attachment of the 1-napthoyl group on the indole ring. The electron ionization mass spectra showed similar major fragment ions with a molecular radical cation of significant abundance at m/z 359. The six compounds have similar fragment ions at m/z 127 and 155 for the naphthyl and naphthoyl cations. There is a prominent fragment ion at m/z 342 [M−17]+ in the EI-MS of 1-(5-fluoropentyl)-3-, 4-, 5- and 6-(1-naphthoyl)-indoles due to the loss of the hydroxyl group and this ion is most prominent in the 3-(1-naphthoyl) substituted isomer (AM-2201). The six compounds were separated using gas chromatography on a capillary column containing a trifluoropropylmethyl polysiloxane (Rtx-200) stationary phase. The elution order appears to be related to the steric crowding of the indole ring substituents. The 7- and 2-(1-naphthoyl) substituted isomers eluted first due to the possibility for maximum interactions between the naphthyol and alkyl side-chains. The vapor phase infrared spectra differentiate among these six compounds based on the position of the 1-naphthoyl group on the indole ring. The vapor phase spectra for these compounds are compared to the non-fluorinated analogues, JWH-018 and its regioisomeric equivalents. (publisher abstract modified)