The LD50 of n-butanol adjusted for its intoxicating potency is about 1.5 times that of ethanol. This would mean to me that n-butanol is therefore 50 % safer than ethanol. Why is it not used to replace ethanol in the alcoholic drinks?
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1$\begingroup$ Economics. Fermentation from natural fruits is easy (and therefore cheap) and produces ethanolic beverages. Anything else is hard and expensive. And people who want to drink enough to damage themselves (therefore risk getting close to the lethal dose) care about the cost more than they care about anything else. $\endgroup$– matt_blackCommented Feb 12, 2017 at 20:58
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3$\begingroup$ LD50 is a poor metric for toxicity. The harms from ethanol occur at much lower levels and there is little to suggest that alternative alcohols would be better (or have the same positive effects either). $\endgroup$– matt_blackCommented Feb 25, 2019 at 15:52
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5 Answers
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Alcoholic beverages historically all stem from some kind of natural fermentation. The first step for all of them is to take something containing carbohydrates (grapes, wheat, …), mix it with water and yeast and wait for alcoholic fermentation to kick in. The yeast will then reduce the sugars to alcohol in a process than can be represented by the following simplified equation:
$$\ce{C_nH_{2n}O_n -> n/3 C2H5OH + n/3 CO2 + $E$}\tag{1}$$
Wherein $E$ represents the energy liberated and used to co-synthesise $\ce{ATP}$ for the yeast to use in growing.
$$\ce{ADP^3- + H2PO4- -> H2O + ATP^4-}\tag{2}$$
Thus, ethanol naturally happens to be part of alcoholic beverages — taking grapes and wheat would give wine and beer, respectively.
Some alcoholic beverages are then further enriched by distillation, reducing the water content or increasing the ethanol content. This adds nothing to the original solution, it only serves to remove some particles; ethanol being one of the prominent ones not to be removed.
To replace ethanol with, for example, n-butanol would require a complicated setup in which you attempt to extract the ethanol once your alcoholic beverage is completed and then re-add butanol. While some distilleries may be able to market these drinks as exceptionally high-class (because the process will be <insert profanity here> expensive), for most this will not even be considered an option.
Note, by the way that alcohol-free beer is typically made by extracting the alcohol from conventionally brewed beer (which is why up to $0.5~\%$ alcohol iirc are permitted to remain; everything else would drive up the process costs exorbitantly). Many people complain about alcohol-free beer not tasting like ‘proper beer’ because aroma compounds have also been extracted as ‘collateral damage’ of the process.
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$\begingroup$ We should not be concerning ourselves with natural fermentation. I thought this sort of hypothetical question containing a giveaway hint "alternative" should be clear to inquire about ways to create beverages other than by natural fermentation. $\endgroup$– aiagCommented Feb 12, 2017 at 19:52
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3$\begingroup$ @aiag If you were asking about artificially created beverages, you should have stated so in your question. However, that would mean that your question would be very likely to get closed as too broad. $\endgroup$– JanCommented Feb 12, 2017 at 19:56
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2$\begingroup$ @aiag We’re not playing a mistery game where every word is in some way significant. Write a clear and unambiguous question to get an answer. The question you have written as is is clear — but obviously not in the way you intended. Two answers ‘mis’-interpreting it should lead you to start thinking why the misinterpretation could have happened. $\endgroup$– JanCommented Feb 12, 2017 at 20:02
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$\begingroup$ Butanol is about $60/L , given that you need about ten times less, it's just as affordable as the cheapest spirits you can buy. So I'd say it's more tradition and convenience than economics. $\endgroup$ Commented Jan 27, 2022 at 16:00
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First: While people certainly drink alcoholic beverages because they like the taste a lot of people actually want to get intoxicated. So using an alcohol which works less is contra-productive.
Second: We don't usually prepare those beverages by mixing pure ethanol with other things. Most alcoholic beverages are produced by fermentation and mostly ethanol is produced in this process. It wouldn't be easy to use butanol instead, even if we want to.
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1$\begingroup$ You probably missed the part where I calculated toxicity, adjusted for intoxicating potency. Adjusted means taking it into account. Once you take into account that n-Butanol has 6x stronger inxicating potency and adjust its toxicity by that, you would realize that using 1/6th of the amount of ethanol in the same drink would be ~50% less toxic, but at the same time having exact same intoxicating potency. $\endgroup$– aiagCommented Feb 12, 2017 at 17:08
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$\begingroup$ And 2nd, asking this question on Chemistry.SE, I do not really care for why people drink and what they think of their drinks, or how those drinks are produced. $\endgroup$– aiagCommented Feb 12, 2017 at 17:10
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$\begingroup$ @aiag well, if they are easily produced with ethanol then there's your answer to the question in the title... I don't know what you want to hear. There's also no real problem with acute alcohol intoxication. $\endgroup$– DSVACommented Feb 12, 2017 at 19:08
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$\begingroup$ It is blatantly obvious that the existing alcoholic drinks are produced "easily". The question is, why a much less toxic alternative is not considered. There are numerous examples of how our society went great lengths to eradicate substances less lethal than ethanol. $\endgroup$– aiagCommented Feb 12, 2017 at 19:54
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1$\begingroup$ @aiag Because there's no real need for it. I guess you looked at the acute toxiticity? There are hardly any people dying from acute ethanol poisoning (and most of them are alcoholics). So you would need to look at the long time toxiticity. And you are also talking about getting rid of something that is a very big deal in several cultures and replace it with something else. Try taking away beer from germans or wodka from russians. You think that's something you could do? $\endgroup$– DSVACommented Feb 12, 2017 at 20:11
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This question could be valid under alcohol tax. After all, Russians allegedly drinks body lotion to get themselves intoxicated, so it's natural to speculate as to why a safer alternative is not used. Of cause, the answer provided below is all just speculation...
- Potency
Looking into the article cited by Wikipedia on potency of 1-butanol, the 6x potency is actually a molar potency. Molar mass of 1-butanol is approximately double that of ethanol, which means per weight you'll get ~3x potency instead. Still good but probably less impressive than previously thought.
Interestingly, the paper cited also reach a conclusion that the structure of alcohol doesn't matter as long as it pass the biological membranes. Thus the question could be extended to other non-toxic alcohols as well.
- Toxicity
With great reluctance the LD50 of ethanol (~7000mg/kg) and 1-butanol (790–4,360 mg/kg) was compared directly. It looks like 1-butanol is more toxic than ethanol. After adjustment for potency as in (1), 1-butanol doesn't look like it offer any safety benefit compare to ethanol
It's hard to compare toxicities of different compounds, unless they have same biological target. Using LD50 could be a way to get a very rough estimate when the LD50 of two compound differ much, say Botulinum toxin vs Alcohol, but it's not really useful otherwise. After all, LD50 consider only lethal effect, not other disturbances to the body. Also because of this LD50 is usually (always?) an estimate from other animal models (hence the range given).
A quick example, table salt (NaCl) has LD50 of ~3000mg/kg. This doesn't convince people that ethanol is less toxic than salt. In fact it's much rarer to have salt intoxication due to differences in consumption pattern, sane people will not keep eating more and more salt until intoxicated.
- Enjoyment factor
Despite similar molar potency, not all alcohols are made the same. Especially flavor / smell, as the nose is one of the best chemical detector available. I bet someone has drunk rubbing alcohol as a kid, which taste like, well, rubbing alcohol. Methanol should smell like ethanol but it could have some plastic like taste. 1-butanol is reported to have a banana odor. Messing with flavor of the beverages is probably not the way to make customers happy, or make fake alcohol.
Another thing with 1-butanol is it's solubility with water. Ethanol is miscible with water, meaning you can make any concentration from 0.000...1% to 100% drink with no problem. 1-butanol is not. With 1-butanol the maximum concentration is ~ 7% (weight per volume), which is again not very delighting for alcoholics.
- Other
As others have mentioned, 1-butanol is not naturally present in drinks. It could be made by fermentation, but this is still an active area of research (mainly for biofuel using Clostridium species of bacteria instead of yeast, if Wikipedia tells truth). More likely, it is synthesized from petroleum and doped into drinks that are not psychoactive in hope to provide some psychoactive effect (is this even legal?). It is not used to substitute ethanol from beverages as removing ethanol from products already with itis going to be expensive and remove some flavors already present.
Well it doesn't sound that good to use 1-butanol for alcoholics. Maybe a better way to do things would be to use alcohol dehydrogenase inhibitors like Fomepizole to reduce metabolism of ethanol to acetaldehyde, which cause most of the toxic effect of ethanol, specifically a Group 1 carcinogen that contributes to hangover. This also allows you to "get more with less", have greater effect with less drinks. Wait this thing cost U$D1000 per dose? Oh well.
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The production of bio-butanol remains a tricky technical challenge. The absolute highest n-butanol titres produced by fermentation are below 3% by volume (compared to the 10-15% easily achieved for ethanol), and those titres were achieved in lab conditions using hyper-specialized microbes, which tend to be outcompeted or to evolve away from butanol production in scale processes. They also produce acetone as by-product, which is rather problematic and requires separations more specialized and selective than basic distillation. In short, the overall industrial intensity (both OPEX and CAPEX) of producing butanol for drinking would be a multiple of that for producing ethanol for drinking, possibly an order of magnitude higher. This would carry over into products in the form of enormously increased price.
Pursuing it, therefore, would require extremely strong motivations to do so, and it seems unlikely that butanol-containing drinks would be competitive in the market.
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To answer your question directly, the most likely reason nobody is using n-butanol is because nobody has ever tried. Few people have sufficient knowledge of chemistry to even think of your question and then when you multiply that by the percentage of those people with manufacturing skills and an entrepreneurial personality, the chances are very very small of it happening.
Manufacturing a new product requires making thousands of decisions and solving hundreds of problems. How will you deliver the n-butanol? In a beverage? Which one? How will it taste? How will you manufacture it? How pure do you need it? Will it be regulated by the government differently than ethanol? Is it a drug subject to FDA (probably not)? ....and there are many many more issues to be resolved.
If you want to invent a new alcoholic beverage, just start experimenting. Put some n-butanol in beer or wine and see what it tastes like. Or if you are concerned with safety, create your mix and then kill some mice with it to see if it has the same LD50 as straight n-butanol.
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$\begingroup$ Isn't alcoholic beverage industry a huge multi-trillion conglomerate with virtually unlimited powers? Think Bacardi and Philip Morris who owns a huge share of alcohol industry. They run sophisticated labs with multi-billion dollar budgets. And then think government agencies like BATFE etc with their own multi-billion dollar budgets. There should be at least some consideration given between those of what sorts of alcohol are more or less toxic per drink. $\endgroup$– aiagCommented Aug 1, 2017 at 23:45