Boomer Posted July 31, 2006 Posted July 31, 2006 Anyone here tried some alkyl halide from scratch? I recently failed miserably on ethyl iodode, following two Rhodium refs (one modified): Heated ethanol (the good stuff, 96% non-denat.) with 70% sulfuric and KI in a water bath for two hours, then extracted the organic with pentane. Trying to evaporate the latter gives zero yield, I guess they either boil too close, or only traces formed. It *did* smell differently after heating though. On try No. 2 I followed the other book to the letter, heated in a sand bath, slowly, until "ethyl iodide just distils over". Changed the receiver at 3ml, just before some red stuff started to come over. The distillate was a clear yellow liquid, quite mobile, but surprisingly when dropped into water sank down while *dissolving rapidly and completely*! Made the additional mistake to smell it, a good whiff was rewarded by a burning chest and a bad cough for two days. What on earth *is* it then, (di)ethyl sulfate? At 30% water content? At least the worst pain is over by now....
Boomer Posted August 1, 2006 Author Posted August 1, 2006 To finish your quote: "...store it in an amber glass bottle in a refrigerator until use. Step 2: Preparation of nitroethane Into a standard flask, equipped with motorized stirrer or other stirring means, place 500 milliliters (16.9 fluid oz.) of dimethylformamide (DMF), followed by 30 grams (1 oz.) of sodium nitrite. Thereafter, stir this entire mixture to form a uniform mix, and then place this mixture into a cold-water bath. Afterwards, carefully and gradually add in, 27 grams (0.95 oz.) of ethyl bromide (prepared in step 1)... From the Kings chemistry survival guide first edition" Thank you anyway, though that was exactly the synth (from Rhodium mirror) I followed on the second try, apart from using KI. Only difference was I had no means of stirring in the sand bath, the use of which was necessary for lack of a heating mantle (water bath to cold, see try No1, oil bath too stinky). Plus, it was recommended in a synth for the *iodide* I found somewhere else. BTW do you (too) store all your posts on HD? The paragraph about the 37ml nearly gone rang a bell. SMDB? P.S: Your edit explains why red stuff came over later, and why the first mix is deep purple, even after extraction. Oh and I found the ref! The second of the following two methods is the source of try No1, but using 70% sulfuric for the phosphoric like in method 1: ---- From Rhodium mirror (by Rhodium himself) ----- Preparation of Ethyl Iodide Method 1 A mixture of 500 g (3.94 mol) of iodine, 800 mL of 84% (w/v) ethanol, and 60 g (2.224 mol) of aluminum foil in small pieces is warmed gently. Once started, the reaction increases progressively in vigor, but can be controlled by cooling; it subsides in about 10 min, and is complete in an hour. The product is distilled until deep red fumes appear. A cold mixture of 700 mL of 84% ethanol and 400 mL of 85% sulfuric acid is added to the cooled residue. After 15 min, distillation is begun, and continued until no more oily drops form in the water in the receiver. The yield of crude ethyl iodide is 260 mL (504 g; approx. 80% yield). Method 2 1 mole of alcohol and 2 moles of KI (or equimolar amount of NaI) are added to 2.96 moles of 95% phosphoric acid. Reflux the mixture 3-4 hrs. A two-phase mixture will result. Add water and ether to the reaction mixture. Seperate the ether layer, decolorise it with Na-thiosulfate, wash it with saturated NaCl solution and dry it with Na2SO4. Evaporate the ether and distill the remaining alkyl iodide to get ~90% yield. Since I spilled the beans (what the iodide is for), these days I may try to convert both the extract and the distillate to EtNO2, just to see what happens.
Boomer Posted August 9, 2006 Author Posted August 9, 2006 Small update: The myterious clear yellow liquid that I distilled from 70% sulfuric, EtOH and KI mixes with water in any proportion, burns with a blueish flame, and starts boiling at 40C.It keeps boiling while decreasing little in mass till it hits 78-80C, there it lingers until it is gone. Oh and during the process the colour and smell disappear. Guess what, I made some ethanol with some dissolved HI.
Boomer Posted August 11, 2006 Author Posted August 11, 2006 Tried "Method 1" from 3 posts above, the one with elemental iodine and al foil. At just 20 mmol (downscaled 200x) warming constantly was called for, apart from that everything went fine until "The product is distilled until deep red fumes appear". Distil what, the residue with Al crap and Al iodide still in it, or do you separate the liquid first? I went for the former, since I guess the iodide is little soluble in the alcohol, and is needed in the last step. Why was Al left anyway, it was in excess?Up to 100C (W/B) NO fumes appeared, but the alc evaporated fine. Will add the by-now-pre-cooled acid/EtOH mix this evening and go from there. We'll see.... On a side note, why is sulfuric called for, in spite of it oxidising the HI back to iodine? Does the Al salt work as a catalyst, like AlCl3 in some organic reactions, or like the SnCl2 (lewis acid) in the ethyl chloride synt from HCl(aq) + EtOH? Or does it simply lower reaction temp to prevent oxidation? P.S. How *does* EtI smell then? Just curious...
Boomer Posted August 18, 2006 Author Posted August 18, 2006 I think I'll stick with HEs if it goes on like this! Finished "Method 1" above, 6ml of a clear yellow liquid distilled from the bottle in the oil bath. Put some into three volumes of water and guess what? It dissolved completely, so wrong product AGAIN. Made some more elemental iodine from 10g of the KI. At least THAT works like a charm (90%+ yield). With the (expensive!) Na2S I recently aquired, making 57% HI should be easy. Maybe the straight HI/EtOH route is more promising. At least HI is something I cannot buy from the pharmacy... I start to think that ethyl iodide is for me what picric is for Mumbles!
Mumbles Posted August 18, 2006 Posted August 18, 2006 I start to think that ethyl iodide is for me what picric is for Mumbles! Wow, that bad? To be fair I did get some picric, I just had to extract it from the red goo after I let it dry. Well, I never isolated the product alone(It dissolved), but I saw it so I know I at least made some.
Mr. Crackle Posted September 12, 2006 Posted September 12, 2006 This may be stupid but I have just started studying organic chemistry. If I bubble two moles chlorine through one mole isopropyl alcohol I should get one mole 2-chloro-isopropanol and one mole HCl....right? Lets say I did get that product and add a mole of NaOH, would it form an alkene, water, and salt? I apologize if this does not fit the topic.
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