Hydroiodic Acid Preparation
This experiment involves high temperatures and strong acids proper safety equipment must be worn at all times hydroiodic acid is a very useful asset to convert primary alcohols into alkyl halides the resulting album halide can be used in many reactions such as the grignard reaction hydroiodic acid is also famously known for juice in the production of methamphetamine
I highly advise against the attempt of synthesizing any illegal chemicals also i won’t answer any questions relating to the production of anything illegal for this experiment i used 20 grams of potassium iodide 11.5 milliliters of 75% phosphoric acid and some 10% sodium hydroxide solution the entire procedure and all the information was obtained by the step by
Step right up by our gox found in the arrowwood archive first 100 milliliter flask was charged with 20 grams of potassium iodide a few boiling chips were then dropped in then 11.5 milliliters of 75% phosphoric acid was added a base trap was set up using 10% sodium hydroxide and an inverted funnel the inverted funnel is used to prevent suck back from occurring a
Distillation setup was prepared and the heat was cranked to max the collecting flask is also initially filled with 10% sodium hydroxide the use of the sodium hydroxide is extremely important and i’ll explain why when using low grade phosphoric acid traces of sulfur will exist this will lead to the production of hydrogen sulfide if your asset contains sulfur the
Initial distillate that comes over might be milky white the hydrogen sulfide contained in the distillate will be destroyed by the sodium hydroxide in the collecting flask however the more dangerous gaseous hydrogen sulfide must be destroyed by the sodium hydroxide trapped low concentrations of hydrogen sulfide can easily kill you and the hydrogen sulfide actually
Desensitizes your smell this means that it can still be the even at high concentrations but you won’t smell it how you’re in sulfide is just as poisonous as hydrogen cyanide gas this proper safety precaution must absolutely be taken in my case i used hplc grade phosphoric acid so no hydrogen sulfide was produced when the distillate changes from milky white to reddish
Brown the collecting flask and the trap must be changed replace the collecting flask with a clean empty round bottom flask and replace to the naoh trap with a small amount of water let the distillation run on maximum heat until no more distillate comes over in this distillation both aqueous and gaseous hydraulic acid will be produced the collecting flask is used to
Capture the aqueous portion whereas the trap is used to capture the gaseous portion the reactions that are likely happening are shown above in the first reaction less heat was required and the potassium iodide reacts with the phosphoric acid to produce aqueous hydrolytic acid and monopotassium phosphate at higher temperatures when the water is being boiled off the
Monopotassium phosphate can react with the potassium iodide to produce gaseous hydrolytic acid and dipotassium phosphate be aware however that these reactions are only speculation after the distillation the dilute hydrated in the trap was added to the collecting flask then a few boiling stones were added boil the distillate until the temperature reaches about 127
Degrees celsius everything that comes over below about 125 to 127 degrees celsius is mostly water with some dilute hydrogen gas ‘add it might be worth saving the dilute hydrolytic acid for your next distillation run at this point you can replace the collecting flask and boil everything over or simply remove the heat and collect the nearly pure 57 percent hydroiodic
Acid that remains in the boiling flask the final yield was about 5 milliliters of hydroiodic acid with a density of about 1.71 grams milliliter my yield was quite low only hovering slightly above 30% however it appears that at larger scales the yield is significantly better for unknown reasons according to our gox the efficiency of the 22 liter scale is about 92%
Whereas the efficiency at the 1 liter scale is only 75 percent i didn’t have a use for the hydrolytic acid so it was neutralized using some sodium hydroxide solution
Transcribed from video
Hydroiodic Acid Preparation By Walter White
