Isopropyl Nitrite Synthesis 2.0

by Drone #342

This is the sort of version 2.0 of my synthesis. The only difference is that I include all the appropriate quantitites -- thus making it a more complete report on the best way I've found to make this fascinating compound. I liked the way I originally wrote it, so I'll keep the rest the same as when originally written.

Its been months since I had this dream, but in an alcoholic stupor, I passed out, smacking my head against the floor. In my delerious state, I had a dream.

In my vision, a leprechaun was sitting on a giant toadstool, reading UF's SOMM. He read the bit about making alkyl nitrites, clapped his little hands, and said "Saints preserve us! I'm going to me me a wee bit o' the old isopropyl nitrite!" In a mad dash, the plucky little imp ran to his pot-o-gold, took out a few coins, and ran off to the grocery store, where he purchased some distilled water and regular 91% IPA. He put the IPA in the freezer, and went on with his business. He then dashed off over the rainbow, and came back with a package of sodium nitrite and a bottle of lab-grade sulfuric acid. He put the sulfuric acid in the refrigerator. He sat down, and redid the "recipe" in the book, converting the butyl nitrite recipe into a isopropyl-based version. He then went about labelling two beakers, one "A", the other "B". In beaker "A", he disolved the sodium nitrite (95 g) in H2O (375 ml), then placed it in the freezer. In "B", he mixed the alcohol (83 ml of 91% iPrOH) with a small amount of water (18 ml distilled H2O), and then slowly added the concentrated H2SO4 (34 ml), doing his best to keep boiling to a minemum. After the addition, he put beaker "B" into the freezer, and went about taking a nap.

At this point, I began to come to my senses. I stood up, thought "what a peculiar dream" and went back to my self-destructive marathon binge-drinking. When I finally slipped into my potato vodka-induced coma, I began dreaming right where I left off.

The little leprechaun woke up, looked at his wee digital wristwatch, and said in a cute little Irisg leprechaun voice, "Fer FUCK's SAKE! I've overslept!" In a hurried dash, he went to the freezer, and saw that beaker "A" was essentially a sodium nitrite-flavored slushy. "Bleargh!" He then started swearing violently in Gaelic, and I noticed flowers wilted around him as a result of the sound of whatever nasty things he was saying.

In a fit of fury, he placed beaker "A" in an ice bath, tossed the now thoroughly-chilled acidic IPA contents of beaker "B" into the sodium nitrite slurry of beaker "A", and began stirring madly. "...And Mary wept!", he cursed. He did not add it slowly; he just tossed it right in! The reaction was pretty immediate, and when the little fellow came to his senses, he realized how foolish it was to add everthing so quickly -- after all, everybody says "add it slowly, so as to not allow the temperature to rise too quickly." Well, the funny little mythical character looked at the solution, in a matter of seconds, a very nice layer of isopropyl nitrite floated to the top. It was decanted and dried. The yield was around 85%-90%, from the nitrite. He was so happy, he did a little jig in celebration. The fumes of the nitrite got to him, and soon he was dancing MUCH slower. All the blood from his wee body rushed into his jugulars, and he left the room so he could catch his breath. "Saints be praised!", and he slumped over. The little leprechaun sat and thought about what he learned: by simply chilling everything in the freezer before mixing, and using an external icebath, a person can get better yeilds simply by recklessly pouring the two solutions together than by following the advise of Uncle Fester. All-in-all, the little chemical leprechaun had a good day.

At that point, I woke up, rolled over, evacuated the contents of my stomach using my right index finger, and went back to sleep; truly it was an interesting dream, but having a head injury and a hangover left me unable to enjoy the insights that it gave me.

Still, I thought you'd all enjoy hearing it.

Posted to the Hive by Entropy 02-02-99:

Just a few tidbits of information I thought may be helpful for those interested in going this route. Someone who isn't me wanted me to relay this info to avoid the dilemmas they encountered.

1. When preparing Solution B according to Drones notes, it is imperative that the H2SO4 be added very slowly. Adding it too rapidly will scourch the alcohol and make it useless, not to mention the horrific odor that seems to linger forever.

2. When it comes time to mix Solution A with Solution B, don't just dump the two together as Drone's notes may have inferred. Doing so will release a quite impressive orange/red mushroom cloud that will send you running for cover. Instead, add B to A SLOWLY!

This is best accomplished by placing Solution A into a round bottom flask and chilling in an acetone/salt/ice bath on a stirrer. Connect a Clasien adapter to the top of the flask containing Soln A. To the Straight arm of the clasien, connect an addition/sep funnel containing SOLN B. The addition/sep funnel should be modified by attaching a piece of tubing so that the solution is delivering BELOW the fluid line of SOLN-A. THIS IS VERY IMPORTANT! You will be sorry if you omit that step. The curved arm of the clasien is fitted with a gas connector to which a piece of tubing is connected and ran out the window (ALSO VERY IMPORTANT). A stirbar should be placed in SOLN-A and stirring began before putting the addition/sep funnel in place. Once the addition/sep funnel is in place, the SOLN-B should be added over a 10 minute period of time.

Pentyl nitrite

Equip a 1-litre three-necked flask with a powerfull mechanical stirrer, a separatory funnel with stem extending to the bottom of the flask and a thermometer. Cool the flask in a mixture of ice and salt. Place a solution of 95 g (1.38 mol) of 'AnalaR' sodium nitrite in 375 ml of water in the flask and stir. When the temperature is fallen to 0°C (or slightly below) introduce slowly from the separatory funnel a mixture of 25 ml of water, 62.5 g (34 ml) of concentrated sulphuric acid and 110 g (135 ml, 1.25 mol) of pentan-1-ol, which has previously been cooled to 0°C. The rate of addition must be controlled so that the temperature is maintained at +/- 1°C; the addition takes 45 - 60 minutes. Allow the mixture to stand for 1.5 hours and then filter from the precipitated sodium sulphate. Separate the upper yellow pentyl nitrite layer, wash it with a solution containing 1 g of sodium hydrogen carbonate and 12.5 g of sodium chloride in 50 ml of water, and dry it with 5-7 g of magnesium sulphate. The resulting crude pentyl nitrite (107 g, 73 %) is satisfactory for many purposes smile. Upon distillation, it passes over largely at 104 °C with negligible decomposition. The B.P. under reduced pressure is 29°C/40 mmHg.

Hexyl nitrite

Hexyl nitrite may be prepared similarly by using 95 g (1.38 mol) of 'AnalaR' sodium nitrite in 375 ml of water; a mixture of 25 ml of water, 62.5 g (34 ml) of concentrated sulphuric acid and 127.5 g (156 ml, 1.25 mol of hexan-1-ol). The yield of crude product is 124 g (76 %). B.P. 129 - 130.5 °C or 52 °C / 44 mm Hg.

Butyl nitrite

For butyl nitrite use the same quantities as for hexyl nitrite, but with 92.5 g (114 ml, 1.25mol) of butan-1-ol replacing the hexan-1-ol. The yield of crude product is 110 g (85 %). Butyl nitrite boils at 76.5-77.5°C at atmospheric pressure with slight decomposition, but distills unchanged at 27°C/43 mmHg.

Reference: Vogel's Practical Organic Chemistry, 5th ed., p 413