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I am doing a chemistry investigation and one component of that requires me to synthesize ethanol from ethene. Ethene itself is gaseous at room temperature and pressure so I was wondering if someone could suggest how I can carry out this synthesis with the use of acids to obtain ethanol.

To give you an idea of what I am actually doing for this investigation, I am trying to find the yield of ethanol when ethene is hydrated using different acid catalysts. However, because ethene is gaseous, I don't know how I am going to actually do this experiment.

To further clarify, I know what reagents I need to use and I know the mechanism of the reaction, I just don't know how to do it practically within a laboratory setting.

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    $\begingroup$ Addition of water to ethene requires high temperatures (~300ºC) and possibly high pressures too. I'm afraid that common lab glassware won't cut it. You will need to keep a pressurized environment of a potentially explosive gas, so safety might be an issue. $\endgroup$ – Variax Nov 30 '16 at 10:17
  • $\begingroup$ Well, kudos to @xyz123 who has found a good laboratory process of preparing ethanol from ethene. To my dismay, I couldn't find any proper laboratory preparation but I would like to point out that making ethanol from ethene is actually an industrial process. $\endgroup$ – Nilay Ghosh Nov 30 '16 at 11:31
  • $\begingroup$ Of course , of course. They would use high pressures and relatively high temperatures for that process (Oh alright, 300 isn't really that high but whatever). I was looking for a way to do it in the laboratory. Thank you for your help :) $\endgroup$ – Abhijeet Vats Nov 30 '16 at 11:36
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    $\begingroup$ The lack of literature for a laboratory setting should be an indicator, that this is probably not that easy to achieve and maybe also a bit too dangerous. $\endgroup$ – Martin - マーチン Nov 30 '16 at 11:41
  • $\begingroup$ I don't think the lack of literature says that, @Martin-マーチン I think the real issue is no chemist would want to synthesize in a laboratory a very cheap, widely available product from a gaseous reagent. It's probably and likely like you could achieve this via a hydroboration oxidation, but heck, even in that case, it's easier just to start from triethylborane. Industrially, it's a different story altogether as the economics may be very different. $\endgroup$ – Zhe Dec 1 '16 at 1:55
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You should try bubbling the ethene gas through dilute sulfuric acid. It should form ethyl sulfate and get hydrated with water forming ethanol. As the gas will bubble through the solution, you should have an ample amount of liquid so that most of the gas can maximally react with the sulfuric acid before bubbling out as gas. You should do the reaction in a fume, hood too. Then I think that you could separate the ethanol from the water by distillation of the ethanol from the mixture, or you could separate it by exploiting the great difference in the freezing points of ethanol and water.

If you could connect tubes in such a way with special chemistry glassware, then maybe you could make some kind of reflux apparatus like an acid reflux apparatus where the gas funnels back into the bottom of the liquid and cycles through several times then you could increase your yield. Just if you use some cyclic mechanism, don't release the gas too quickly or you could break your apparatus.

I'm not exactly sure what the experimental design is. But due to the concentration of gas in the reaction chamber, it's important to have an escape valve for the gas for safety purposes of equalizing pressure. If you know what you want, an experienced glass-blower can make your apparatus.

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  • $\begingroup$ Thanks for the reply. I just need to check two main things; 1. What should my set up look like? Currently, my idea is to use a set up where I synthesize ethylene from ethanol by heating the ethanol in a boiling tube and letting the gas flow from the boiling tube, through a glass tube into a container which contains my acid solution and another test tube, which is where I'll collect my ethene and where it will be bubbled into the acid solution. Is that fine? Below that container will be a bunsen burner to provide the heat. 2. Should I use organic acids as well as inorganic acids? $\endgroup$ – Abhijeet Vats Nov 30 '16 at 11:24
  • $\begingroup$ Could you backup this method with some literature or a general procedure? How effective is that, given that those reactions are equilibria and without removing the ethanol, will not be very effective. How do you get rid of the sulfuric acid? If you would go ahead and distil the mixture, it will just cleave ethanol again. Most importantly you should perform chemical reactions always in a fume hood. $\endgroup$ – Martin - マーチン Nov 30 '16 at 11:39
  • $\begingroup$ Patent US 2,683,731 gives some technical details. An older patent US 2,497,959 describes the process with 60-65% sulfuric acid. During the process, diethyl sulfate might be formed too. The GHS statements H340 and H350 add an interesting twist to the procedure. Well, you can't live forever... $\endgroup$ – Klaus-Dieter Warzecha Nov 30 '16 at 12:21

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