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Book II of PiHKAL: A Chemical Love Story, by Alexander & Ann Shulgin #49: 2C-T-21
#49 2C-T-21: 2,5-Dimethoxy-4-(2-fluoroethylthio)phenethylamine

#49 2C-T-21 SYNTHESIS: To a solution of 6.9 g of KOH pellets in 100 mL hot MeOH, there was added 13.0 g 2,5-dimethoxythiophenol (see under 2C-T-2 for its preparation) followed by 9.6 g 2-fluoroethyl bromide. The reaction was exothermic, with the immediate deposition of white solids. This was allowed to stand for 2 h, added to 1 L H2O, and extracted with 3×75 mL CH2Cl2. The extracts were pooled and the solvent removed under vacuum. The residue was 2,5-dimethoxyphenyl 2-fluoroethyl sulfide which was a colorless oil and weighed 17.2 g. It was sufficiently pure for use in the next reaction without a distillation step.

A mixture of 26.8 g POCl3 and 24.8 g N-methylformanilide was heated for 10 min on the steam bath. To this claret-colored solution was added 17.0 g of 2,5- dimethoxyphenyl 2-fluoroethyl sulfide, and the mixture heated an additional 25 min on the steam bath. This was then added to 1.5 L of well-stirred warm H2O (pre-heated to 55 °C) and the oily phase that formed solidified almost immediately. This brown sugar-like product was removed by filtration, and washed with additional H2O. After sucking as dry as possible, the residual solids (weighing 19.0 g wet) were dissolved in an equal weight of boiling MeOH which, after cooling in an ice-bath, deposited pale ivory colored crystals of 2,5-dimethoxy-4-(2-fluoroethylthio)benzaldehyde. This was air dried to constant weight, which was 15.1 g.

To a solution of 15.0 g 2,5-dimethoxy-(2-fluoroethylthio)benzaldehyde in 75 mL nitromethane there was added 1.35 g of anhydrous ammonium acetate, and the mixture was heated on the steam bath for 70 min (the progress of the reaction must be followed by continuous TLC monitoring). The clear deeply-colored solution was decanted from some insoluble material and the excess nitromethane removed under vacuum. There resulted 17.78 g of almost dry brick-red crystals which were dissolved in 110 mL boiling EtOAc. After cooling overnight in the refrigerator, the crystalline product was removed, washed with EtOAc, and air dried. There was obtained 14.33 g of 2,5-dimethoxy-4-(2-fluoroethylthio)-β-nitrostyrene as bright orange crystals.

A solution of LAH (140 mL of a 1 M solution in THF) was cooled, under He, to 0 °C with an external ice bath. With good stirring there was added 3.7 mL 100% H2SO4 dropwise, to minimize charring. This was followed by the addition of 8.9 g 2,5-dimethoxy-4-(2-fluoroethylthio)-β-nitrostyrene in 40 mL of hot anhydrous THF (a heat lamp was needed to keep the nitrostyrene in solution). As the nitrostyrene entered the hydride solution, there was an immediate loss of color. After 1 h stirring at room temperature, the temperature was brought up to a gentle reflux on the steam bath, then all was cooled again to 0 °C. The excess hydride was destroyed by the cautious addition of 15 mL IPA and the inorganic solids were made white and filterable by the addition of 15 mL 15% NaOH. The loose cottage-cheesy solids were removed by filtration, and washed with additional THF. The filtrate and washes were pooled and stripped of solvent under vacuum providing 7.39 g of a pale amber oil. This was dissolved in 600 mL dilute H2SO4, and washed with 3×50 mL CH2Cl2 (which removed the light yellow color). The aqueous phase was made strongly basic with 25% NaOH, extracted with 3×75 mL CH2Cl2 and, after pooling, the solvent was removed under vacuum leaving 4.91 g of product as an oil. This was distilled at 145–160 °C at 0.4 mm/Hg giving 3.91 g of a white oil. This was dissolved in 40 mL IPA and neutralized with 35 drops of concentrated HCl. The beautiful white solids that formed were removed by filtration, and washed with IPA. All were suspended in, and ground under, 40 mL anhydrous Et2O, refiltered and air dried. The final weight of 2,5-dimethoxy-4-(2-fluoroethylthio)phenethylamine hydrochloride (2C-T-21) was 4.07 g of glistening white crystals.

DOSAGE: 8–12 mg.

DURATION: 7–10 h.

QUALITATIVE COMMENTS: (with 6 mg) “I noticed something undefined within five minutes which went away. Within 15 minutes I noticed a definite awareness of activity. There was a progressive increase in awareness of something happening over the next two hours with a plateau of perhaps an hour then occurring. The nature of the happening, as usual, was not clear. During the experience I was more talkative than I usually am. I seemed to be interacting with all others. There was no euphoria but, then, there was no body load or nausea, nor was there any nystagmus. I found a little mental confusion at the peak and there was some searching in my memory bank for the right chips at times. I lost the entire line of one of my conversations at one point during the plateau and had to ask what I was talking about. I tested my visual field on a painting and with sufficient concentration I could get the center part to wiggle a little. I didn’t try to observe anything with my eyes closed. I feel that there was something physical about the eyes. In the evening, after-images were quite intense, and the next day my eyes seemed tired or bothered. What can I say? The material was pleasant and I certainly got the feeling of being high but not getting too much out of it. There were no insights or “ah-hahs.” I wonder if periodic and frequent use (say twice a day) at the one or two milligram level would be a positive mood enhancer?”

(with 8 mg) “Comes on very gradually and slowly. Takes about an hour to feel. Reasonably intense in two hours, ++. Very pleasant material, enhancing communication, clear thinking, good feeling. There is a feeling of closeness; the bondedness with the group grows steadily during the day, reaching a highly rewarding level. For me a couple of firsts regarding food. I was hungry only two hours into it. I usually don’t want food ’til well down as I usually feel that it interferes with the experience. And, also, I nibbled constantly as I felt that there was nothing in my body. And I enjoyed it thoroughly, feeling only the warmth and energy, with no contrary developments. There was a nice feeling of inner strength and peace.”

(with 8 mg) “It was very difficult to fix the times of ascent or descent. Some chilling during onset but not later. And there was some yawning and ear-popping. It is easy on the body, in no way threatening. This time I am very relaxed and somewhat lethargic; the visuals are not too pronounced. Excellent sleep.”

(with 10 mg) “I find I can use it if I set my energy in a direction I really want to go in. Otherwise I can just be stoned and self-indulgent. Not out-of-body cosmic at all. But it’s good material, an ally, not presenting hidden negatives.”

(with 12 mg) “Well … 12 milligrams is quite enough for a +3, which was established within the first hour and plateau’d by the end of the second. Body felt quite safe, again, but there was considerable push of energy. I did not feel particularly interested in doing anything like writing and in fact preferred to watch television while rocking a bit on the couch, to ease the push. Mood was faintly grim, but not more than faintly. I noted something that I hadn’t seen before with this material: time slowing. The first two hours seemed to last a very long time. There was no anorexia. It wasn’t until 10 p.m. [fifth hour] that the idea of writing had any appeal at all. By then, I was still +3 but a lot more at ease. I wrote two letters and enjoyed the process. Sleep was fine. My mood next day was slightly introverted, not very spontaneous for a while. Late in the afternoon, it was a lot better.”

EXTENSIONS AND COMMENTARY: This is about as potent a phenethylamine as they come. There are a couple in the 2C-G family that are similar in potency, but they are much longer lived. The motivation for the use of the beta-fluoroethyl group can be seen under the discussion of DOEF, where there was an amalgamation of two lines of reasoning: the imitation of potent serotonin agonists with a need of including an atom (the fluorine) that is potentially labelable with a positron emitter. And the mass-18 isotope of fluorine, with a half-life of just under 2 hours, is ideal for many biological studies. In fact, much of the research work being carried out by the Nuclear Medicine group in Berkeley is based on the analogy between a halogen atom and a beta-fluoroethyl group. There are some similarities in pharmacology so that if there is a bromine or an iodo atom present in a drug, it is a fair guess that the corresponding beta-fluoroethyl would also be active. In a sense, the cute (and chemically impossible) idea of putting a bromo atom on the sulfur of the 2C-T family is nicely satisfied by using the beta-fluoroethyl group instead (which is chemically completely possible).

A logical extension of 2C-T-21 is the three carbon amphetamine analogue which should be, by comparing structures and activities, a very potent and interesting material in its own rights. This would be 2,5-dimethoxy-4-(2-fluoroethylthio)amphetamine or, following the nomenclature used with the earlier members of this series, ALEPH-21. A solution of 2,5-dimethoxy-4-(2-fluoroethylthio)benzaldehyde (see earlier in this recipe) in nitroethane with ammonium acetate gave 1-(2,5-dimethoxy-4-(2-fluoroethylthio)phenyl)-2-nitropropene as yellow-orange crystals from MeOH with a melting point of 102–104 °C. And that is where the project now stands. It has not yet been reduced to the amine.

This phenethylamine, 2C-T-21, was the last of the 2C-T’s to be completed. A couple of other sulfur analogues have been given numbers, and have been started, but the syntheses are still at some intermediate state.

The n-butyl compound, named 2C-T-19, has been taken to the nitrostyrene stage. Reaction between 2,5-dimethoxythiophenol and n-butylbromide with KOH gave 2,5-dimethoxyphenyl n-butyl sulfide as a colorless oil. This, with phosphorus oxychloride and N-methylformanilide, provided 2,5-dimethoxy-4-(n-butylthio)benzaldehyde as pale orange solids from MeOH, with a melting point of 78–79 °C. This, with nitromethane and ammonium acetate, gave 2,5-dimethoxy-4-(n-butylthio)-β-nitrostyrene, with a melting point of 133–134 °C from either IPA or acetonitrile.

The 2,2,2-trifluoroethyl compound, which I have named 2C-T-22, has been taken to the benzaldehyde stage. Reaction between 2,5-dimethoxythiophenol and 2,2,2-trifluoroethyliodide with KOH gives 2,5-dimethoxyphenyl 2,2,2-trifluoroethyl sulfide as a very pale amber oil. This, with phosphorus oxychloride and N-methylformanilide provided 2,5-dimethoxy-4-(2,2,2-trifluoroethyl)benzaldehyde as crystals that proved to be exceedingly difficult to purify. Yellow solids can be obtained from several solvents, and they melt in the 70 °C area. The initially isolated fraction melted at 69–72 °C and showed three major spots by both TLC and GCMS. The largest GC peak was the correct product with a parent peak of 280 m/e, and cracking fragments at 154 and 234 m/e. A small sample was finally obtained from hexane with a melting point of 78–79 °C but I am not sure that even it is particularly pure. Not surprisingly, the reaction of this crude benzaldehyde with nitromethane and ammonium acetate gave a nitrostyrene product that was a complex mixture. And there that project also rests.

A couple of additional efforts warrant comment. The reaction between trifluoromethyliodide and 2,5-dimethoxythiophenol should have produced 2,5-dimethoxyphenyl trifluoromethyl sulfide, but it didn’t produce anything. And one more. What about a bare thio group at the 4-position in this 2C-T-family? Maybe this can be protected through everything as the disulfide, and be reduced at the last step! The disulfide, 2,5-dimethoxyphenyl disulfide (see under 2C-T-15) was aimed towards the needed bis-aldehyde with phosphorus oxychloride and N-methylformanilide, but all that came out of this were black oils and tars. This has also been abandoned for now.

And it has just occurred to me that there is yet another effort that is certainly worth making, inspired by the observation that 2,2-difluoroethyl iodide is commercially available and not prohibitively expensive. It, with 2,5-dimethoxythiophenol, and following the obvious steps to the aldehyde, the nitrostyrene, and the final amine, would produce 2,5-dimethoxy-4-(2,2-difluoroethylthio)phenethylamine hydrochloride. It lies exactly half way between the highly potent 2C-T-21 (the mono-fluoro), and the yet to be finished 2C-T-22 (the trifluoro). Let’s be weird, and call it 2C-T-21.5. I will wager mucho that it will be very potent.

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About PiHKAL • info

This version of Book II of PiHKAL is based on the Erowid online version, originally transcribed by Simson Garfinkle and converted into HTML by Lamont Granquist. I drew also on “Tyrone Slothrop’s” (Unfinished) Review of PIHKAL to enumerate the many analogues mentioned in PiHKAL but not described at length. Still others remain to be added.

I have tried here to expunge any artifacts introduced by the earlier transcriptions and restore most of the typographic niceties found in the printed edition. I’ve also made minor changes to some chemical names in line with current nomenclature practice, and in the hope of aligning with more readers’ searches. Typically the change is little more than expanding a prefix and setting it in italics. The errata and changes page has further details.

Cautionary Note

“At the present time, restrictive laws are in force in the United States and it is very difficult for researchers to abide by the regulations which govern efforts to obtain legal approval to do work with these compounds in human beings.

“No one who is lacking legal authorization should attempt the synthesis of any of the compounds described in these files, with the intent to give them to man. To do so is to risk legal action which might lead to the tragic ruination of a life. It should also be noted that any person anywhere who experiments on himself, or on another human being, with any of the drugs described herein, without being familiar with that drug’s action and aware of the physical and/or mental disturbance or harm it might cause, is acting irresponsibly and immorally, whether or not he is doing so within the bounds of the law.”

Alexander T. Shulgin

Copyright Notice

The copyright for Book I of PiHKAL has been reserved in all forms and it may not be distributed. Book II of PiHKAL may be distributed for non-commercial reproduction provided that the introductory information, copyright notice, cautionary notice and ordering information remain attached.

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PiHKAL is the extraordinary record of the authors’ years exploring the chemistry and transformational power of phenethylamines. This book belongs in the library of anyone seeking a rational, enlightened and candid perspective on psychedelic drugs.

Although Sasha and Ann have put Book II of PiHKAL in the public domain, available to anyone, I strongly encourage you to buy a copy. We owe them—and there’s still nothing quite like holding a real book in your hands.

PiHKAL (ISBN 0-9630096-0-5) is available for US$24.50 (plus $10 domestic first-class shipping) from Transform Press.

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