Table of Contents
by Murple, Feb 6, 2001
Taken from PIHKAL by Alexander Shulgin
To a solution of 165 g 1,4-dimethoxybenzene in 1 L of CH2Cl2, in a well ventilated place and well stirred, there was cautiously added 300 mL chlorosulfonic acid. With about half the acid chloride added, there was a vigorous evolution of HCl gas and the generation of a lot of solids. As the addition was continued, these redissolved to form a clear, dark green solution. Towards the end of the addition, some solids were again formed. When everything was stable, there was added 2 L H2O, a few mL at a time, commensurate with the vigor of the reaction. The two phases were separated, and the aqueous phase extracted with 2x75 mL CH2Cl2. The original organic phase and the extracts were combined and the solvent removed under vacuum. The residue weighed 162 g and was quite pure 2,5-dimethoxybenzenesulfonyl chloride, a yellow crystalline solid with a mp of 115-117 °C. It need not be further purified for the next step, and it appears to be stable on storage. The sulfonamide, from this acid chloride and ammonium hydroxide, gave white crystals from EtOH, with a mp of 147.5-148.5 °C.
The following reaction is also a very vigorous one and must be performed in a well ventilated place. To a solution of 400 mL 25% H2SO4 (V/V) in a beaker at least 2 L in size, there was added 54 g of 2,5-dimethoxybenzenesulfonyl chloride, and the mixture was heated on a steam bath. The yellow crystals of the acid chloride floated on the surface of the aqueous layer. There should be 80 g of zinc dust at hand. A small amount of Zn dust was placed at one spot on the surface of this chapeau. With occasional stirring with a glass rod, the temperature was allowed to rise. At about 60 or 70 °C an exothermic reaction took place at the spot where the zinc was placed. Additional dollups of zinc were added, and each small exothermic reaction site was spread about with the glass stirring rod. Finally, the reaction spread to the entire solid surface layer, with a melting of the acid chloride and an apparent boiling at the H2O surface. The remainder of the 80 g of zinc dust was added as fast as the size of the reaction container would allow. After things subsided again, the heating was continued for 1 h on the steam bath. After the reaction mixture had cooled to room temperature, it was filtered through paper in a Buchner funnel, and the residual metal washed with 100 mL CH2Cl2. The two-phase filtrate was separated, and the lower, aqueous phase was extracted with 2x75 mL CH2Cl2. The addition of 2 L H2O to the aqueous phase now made it the upper phase in extraction, and this was again extracted with 2x75 mL CH2Cl2. The organic extracts were pooled (H2O washing is more trouble than it is worth) and the solvent removed under vacuum. The light amber residue (30.0 g) was distilled at 70-80 °C at 0.3 mm/Hg to yield 25.3 g 2,5-dimethoxythiophenol as a white oil. This chemical is certainly not centrally active, but it is a most valuable precursor to all members of the 2C-T family.
To a solution of 3.4 g of KOH pellets in 75 mL boiling EtOH, there was added a solution of 10.0 g 2,5-dimethoxythiophenol in 60 mL EtOH followed by 10.9 g ethyl bromide. The reaction was exothermic with the immediate deposition of white solids. This was heated on the steam bath for 1.5 h, added to 1 L H2O, acidified with HCl, and extracted with 3x100 mL CH2Cl2. The pooled extracts were washed with 100 mL of 5% NaOH, and the solvent removed under vacuum. The residue was 2,5-dimethoxyphenyl ethyl sulfide which was a pale amber oil, weighed about 10 g and which was sufficiently pure for use in the next reaction without a distillation step.
A mixture of 19.2 POCl3 and 18.0 g N-methylformanilide was heated briefly on the steam bath. To this claret-colored solution there was added the above 2,5-dimethoxyphenyl ethyl sulfide, and the mixture heated an additional 20 min on the steam bath. This was then added to 500 mL of well-stirred warm H2O (pre-heated to 55 °C) and the stirring continued for 1.5 h by which time the oily phase had completely solidified to a brown sugar-like consistency. The solids were removed by filtration, and washed with additional H2O. After being sucked as dry as possible, these solids were dissolved in 50 mL boiling MeOH which, after cooling in an ice-bath, deposited almost-white crystals of 2,5-dimethoxy-4-(ethylthio)-benzaldehyde. After filtration, modest washing with cold MeOH, and air drying to constant weight, there was obtained 11.0 g of product with a mp of 86-88 °C. Recrystallization of a small sample again from MeOH provided an analytical sample with mp 87-88 °C. Anal. (C11H14O3S) C,H.
To a solution of 11.0 g 2,5-dimethoxy-4-(ethylthio)benzaldehyde in 100 g of nitromethane there was added 0.5 g of anhydrous ammonium acetate, and the mixture was heated on the steam bath for 80 min (this reaction progress must be monitored by TLC, to determine the point at which the starting aldehyde has been consumed). The excess nitromethane was removed under vacuum leaving a residue that spontaneously set to orange-red crystals. These were scraped out to provide 12.9 g crude 2,5-dimethoxy-4-ethylthio-beta-nitrostyrene with a mp of 152-154 °C. A sample recrystallized from toluene was pumpkin colored and had a mp of 148-149 °C. Another sample from acetone melted at 149 °C sharp, and was light orange. From IPA came spectacular fluorescent orange crystals, with a mp 151-152 °C. Anal. (C12H15NO4S) C,H.
A suspension of 12.4 g LAH in 500 mL anhydrous THF was stirred under He. To this there was added 12.4 g 2,5-dimethoxy-4-ethylthio-beta-nitrostyrene in a little THF, and the mixture was held at reflux for 24 h. After the reaction mixture had returned to room temperature, the excess hydride was destroyed by the cautious addition of 60 mL IPA, followed by 20 mL of 5% NaOH followed, in turn, by sufficient H2O to give a white granular character to the oxides. The reaction mixture was filtered, and the filter cake washed first with THF and then with MeOH. Removing the solvents from the combined filtrate and washings under vacuum provided 9.5 g of a yellow oil. This was added to 1 L dilute HCl and washed with 2x100 mL CH2Cl2 which removed all color. After making the aqueous phase basic with 25% NaOH, it was extracted with 3x100 mL CH2Cl2, the extracts pooled, and the solvent removed under vacuum to provide 7.3 g of a pale amber oil. Distillation at 120-130 °C at 0.3 mm/Hg gave 6.17 g of a clear white oil. This was dissolved in 80 mL IPA and neutralized with concentrated HCl, forming immediate crystals of 2,5-dimethoxy-4-ethylthiophenethylamine hydrochloride (2C-T-2). An equal volume of anhydrous Et2O was added and, after complete grinding and mixing, the salt was removed by filtration, washed with Et2O, and air dried to constant weight. The resulting white crystals weighed 6.2 g.