PCP analog GC/MS interpretation

[negrogesic]

I realize it's a long shot but I was wondering if anyone could offer a read on the following:



Sample was formerly interpreted to be: 3-CL-PCP, unidentified compound x, and PCP, at a ratio of 100:5:1.

Any intuition as to the unidentified compound?

Thanks!

 

[negrogesic]

Not that it makes a difference (ie I'll never get an answer) but here's mass spec data for 3-CL-PCP and PCP for reference:

 

[Delmonte421]

I realize it's a long shot but I was wondering if anyone could offer a read on the following:



Sample was formerly interpreted to be: 3-CL-PCP, unidentified compound x, and PCP, at a ratio of 100:5:1.

Any intuition as to the unidentified compound?

Thanks!

hplc-ms?

I realize it's a long shot but I was wondering if anyone could offer a read on the following:



Sample was formerly interpreted to be: 3-CL-PCP, unidentified compound x, and PCP, at a ratio of 100:5:1.

Any intuition as to the unidentified compound?

Thanks!

you have horrible tailing, whomever made this method for you is an idiot. for mass spec,addup the weight of your molecule and see if the time it leaves the column is there same as the highest number peak

 

[Fertile]

Ah - the crazy world of Chinese instrumentation. I found that NMR seems rare and they do not like to offer it. When you interpret NMR, half the time, it's NOT what they claimed.

Even if provided with NMR they will at first argue the toss until you correctly identify it.... then they just offer what they actually have for less.

So now we know where all this junky product is coming from.

 

[Curious Chemist]

Little bit confused about the info provided because the chromatogram shows only one compound (which is not 3-Cl-PCP or PCP). So I will assume that a GC-MS analysis of your sample shows three peaks (3-Cl-PCP (100%), unknown (5%), and PCP (1%)) of which you only show the first one, correct ? Because if you only see this one peak in your chromatogram your injector temperature is way too low to cleave and evaporate any 3-Cl-PCP hydrochloride that might be present in your sample.

The MS spectrum shows a molecular ion at m/z 192 [M]. The even mass implies that there is no nitrogen (or 2, 4, 6… nitrogens – but that is unlikely). The « isotope pattern » (meaning the relative ratio of about 3/1 for the peak at m/z 192 and the second peak at 194) implies the presence of chlorine (because chlorine naturally occurs in the form of two isotopes: 35Cl and 37Cl in a ratio of 3/1). This is confirmed by the fragment at m/z 157, which equals the loss of chlorine (192 to 157 is the loss of 35Cl and 194 to 157 is the loss of 37Cl). The base peak (highest intensity signal) at m/z 129 corresponds to another neutral loss of 28, which is a C2H4 fragment.

Assuming a molecular formula with just carbon (C), hydrogen (H), and chlorine (Cl) this would imply C12H13Cl. Knowing the alleged origin of the sample (synthesis of 3-Cl-PCP) this should be 1-(3-chlorophenyl)-cyclohexene (SMILES : ClC1=CC=CC(C2=CCCCC2)=C1, UIPAC : 1-Chloro-3-(1-cyclohexen-1-yl)benzene, CAS : 27163-65-1). There is no reference MS spectrum for this compound anywhere to compare with, but the MS fragmentation has everything required for this structure and the dominating peak at m/z 129 would correspond perfectly to a “retro-diels-alder” (RDA) fragmentation to be expected for cyclohexenes.

I won’t talk synthesis here, but it totally makes sense to have this as an impurity from a 3-Cl-PCP synthesis. However, the presence of this impurity at a whopping 5% implies an extremely poor attempt to purify the final product. It’s a water insoluble oil whereas the hydrochloride salt of 3-Cl-PCP is well water soluble – they are extremely easy to separate. If really present at 5% in your sample it implies that producers have learned nothing from the tragedy of MPTP-contaminated 1-methyl-4-phenyl-4-propionoxypiperidine (MPPP) - I am not saying that the 1-(3-chlorophenyl)-cyclohexene is able to form a MPP+ like neurotoxin, but the underlying failure on the level of the synthesis and purification is identical.

That brings me to one last option. Depending on the settings of your GC-injector and the level of maintenance of the instrument this compound might possibly be produced by pyrolysis of your 3-Cl-PCP sample upon injection. If that is true it would not be present in your sample but produced when you inject your sample. You can check this by cleaning the liner and injecting the sample at two different injector temperatures – if the relative intensities remain the same the compounds are present in your sample… but if its relative intensity depends on the injector temperature the compound is produced as an artifact upon injection.