Experimental

1-(4-Fluorophenyl)-2-nitropropene:

6.05 mL of 4-fluorobenzaldehyde (56.4 mmol) was added to a 100 mL round bottomed flask containing 4.26 mL of nitroethane (59.2 mmol). 0.73 mL of 40% methylamine (8.46 mmol) was added to the stirring mixture, and the flask was heated at ~60°C. After about an hour, the flask was cooled to room temperature and 0.81 mL of glacial acetic acid (14.1 mmol) with 50 mL deionized water as added. The flask was then chilled in a freezer, but the light-yellow solution did not crystallize. TLC showed a decent amount of 4-fluorobenzaldehyde remaining, so additional water was added, the flask was swirled vigorously, and once the layers separated the light yellow organic layer was isolated and placed in a round bottom flask fitted with a reflux condensor. Another 4.26 mL of nitroethane (8.46 mmol) was added, followed by 0.25 mL of n-butylamine. The solution was held at reflux for 3 hours forming a dark reddish solution, which was cooled to room temperature and then placed in the freezer. After an hour the mixture was filled with yellow-orange solid. After filtering and recrystallizing the solid from boiling isopropyl alcohol, there was 5.63 g of 4-fluorophenyl-2-nitropropene (31.1 mmol, 55% yield) as shiny yellow spikes, some of which were over an inch long.

1-(4-Flurophenyl)-2-nitropropane:

Within a day the tips of the crystals had turned slightly orange indicating some decomposition, so it's probably best to use it immediately. 2.35 g of old, slightly-chunky sodium borohydride (62.2 mmol) was dissolved in vigorously stirring 30 mL isopropyl alcohol and 10 mL water. The 5.63 g of nitropropene was added in small increments, causing strong foaming and heat generation with each addition, followed by complete loss of yellow color shortly thereafter. Unfortunately, during the addition one portion was added a little too quickly and a small foam-volcano erupted out of the flask... causing some loss. After the rest of the borohydride had been added (whole addition took about 1 hour), it was left to stir for 30 minutes. Still there remained some yellow color. Additional isopropyl alcohol/water was added, and more borohydride was added by the spatula-full until most of the yellow color had disappeared. At least an additional 2 g of borohydride was added, but actual amount not followed. It is likely that the borohydride used was of degraded quality. After an additional hour of stirring, all yellow color was gone. The slurry was filtered through celite (which was washed with additional isopropyl alcohol/water) giving a colorless solution. Solid sodium chloride was added until the solution was saturated and an alcohol layer formed. The alcohol layer was separated, and showed one spot by TLC.

1-(4-Fluorophenyl)-2-aminopropane Hydrochloride:

The Zn/HCOOH reduction may have been done in excess... Comments? The alcohol layer was placed in a round bottom flask and 21.1 g of zinc dust (tech grade, 322 mmol) was added. The solution was stirred vigorously and a reflux condensor was attached. 36.7 mL 90% HCOOH (966 mmol) was slowly added down the condensor over about an hour, causing mild foaming and excessive heat generation; no external heat control was used. Stirring was continued until the mixture returned to room temperature. The zinc was filtered through celite, giving a pink (or perhaps really light red) solution. The filtrate was reduced to about 30 mL by boiling away the isopropyl alcohol at atmospheric pressure. 10% HCl was then added until pH was 1-2. The solution was poured into a separatory funnel and washed with 3 x 25 mL toluene, which removed all of the pink color. The aqueous layer was then basified to pH 12 using high-concentration NaOH solution, occaisionally adding additional water to try to keep everything dissolved. A yellow oil floated to the top of the solution, which was poured into a separatory funnel containing 50 mL toluene. The two-phase mixture was left in the dark for about 2 days before it was separated. The aqueous phase was extracted 2 additional times with 50 mL toluene. The combined toluene extracts were washed with 2 x 25 mL water and an additional 25 mL of brine. The 4-fluoroamphetamine was extracted with aqueous HCl (25 mL water, conc. HCl was added dropwise until shaking gave an acidic aqueous layer). The water was evaporated to give a chunky slightly-yellow solid. The solid was dried under heat lamp, crushed to a very fine powder, and rinsed with ice-cold acetone repeatedly until all yellow had disappeared from the solid. Drying under a heat lamp gave 2.78 g 4-fluoroamphetamine HCl (14.7 mmol, 47% yield) as a powdery white solid.