Eric Lucas wrote:

Forday Wayne Lee wrote:
There is artificial vinegar and vinegar. Artificial vinegar is made through a chemical route, while vinegar is made from microbial fermentation.

Actually it's more complex. It depends on the national regulations, but usually you can get "synthetic" white vinegar, which is just an aqueous ~4-8% solution of food grade acetic acid, "naturally fermented" vinegar which is solely the fermented product, and which can typically have ~4-20% acetic acid ( there is a huge variation in acetic acid contents, I've seen one with over 20% from Germany that was still "naturally fermented" - no mention of any concentration step ), and then you can get various "fortified" vinegars that take a naturally fermented concentrate, and add acetic acid and water to get the desired properties.

The substrate is typically 96% alcohol, but boutique vinegar can use beer, or cider or even port wine. Vinegar is normally brownish in color but can be converted in white vinegar by passing it through activated charcoal.

I have trouble imagining a microbial fermentation of any kind occurring in 96 % EtOH! I suspect the fermentation route probably starts with something like 5 % EtOH, which won't kill the microbes, and gives vinegar that's about 5 % AcOH.

Does anyone know what the actual chemical route to vinegar is? (Please, I know all the different ways to make AcOH, so I'm not interested in speculation; I would like to know what route is actually used.) I know the FDA sometimes specifies the legal route for production of foods and drugs. For example, I understand that the *only* approved way to make medicinal ether is by H2SO4-induced dehydration of ethanol made by fermentation; presumably the particular fermentation bug is also specified by the FDA. This is the only route that was ever approved, presumably because the impurities are minimal, well-characterized, and relatively harmless.

Whilst it's likely that it's to ensure that the ethanol has never been in contact with benzene or any other unknown dehydration agents, azeotropic ("95" or "96"%) ethanol from fermentation was traditionally cheaper to produce than from other sources, and the major new market was for "industrial alcohol" which was going to be denatured anyway.

There was probably no reason for the producers making it from ethylene to seek FDA process approval. Note also that the agricultural alcohol lobby in the USA was ( and still is ) *extremely* politically powerful - consider the $0.54/US Gal. Federal subsidy in fuel ethanol, and the revelations about ADM's activities.

The traditional process for making 5-5.5% "cider" vinegars ( not counting the ancient process of allowing wine to turn to vinegar ) was to use a feed of of 3.4-3.7%v/v acetic acid and 2-2.6%v/v ethanol. If 10% "spirit" vinegar was required, then the feed would be 8.2%v/v acetic acid and 2-2.6%v/v ethanol. In reality, the spirit vinegar was usually made from mixing finished vinegar with dilute alcohol or "low" wines.

The aerobic bacteria, Acetobacter aceti, is traditionally used, and will make up to ~5% acetic acid on cider, malt, or wine feedstocks, with the limitation being the sugar content. If dilute alcohol is used, then up to 12-14% acetic acid can readily be attained before the high acidity harms the bacteria. The fermentation proceeded via acetaldehyde, giving high yields (80-90% of theoretical):-

2C2H5OH + O2 = 2CH3CHO + 2H2O
2CH3CH0 + O2 = 2CH3COOH

Bruce Hamilton

From: Gerald L. Hurst
Newsgroups: rec.pyrotechnics
Subject: Re: Re.: Re: Silver Cleaning
Date: 5 Nov 1995 23:15:46 GMT

In article MalteK says:

So what do I have to call you ?

I suggest you call him "doctor," Master Maltek.

You are not only chemically challenged but to spell ethanol must have been more than a challenge to you.

Sorry, amateur, most chemists would automatically assume that an tyro like yourself meant "ethanol" despite the "al" ending because "acetaldehyde" is the term used by experienced technical people. "Ethanal" is not wrong, it is merely part of the passive vocabulary in contemporary chemistry.

You will get ethanal from ethanol if you let it sit.

No, you won't. Bacteria may produce some of the aldehyde from weakly alcoholic materials such as wine, but alcohol per se is neither attacked by bacteria nor oxidized by atmospheric oxygen.

yes you will also get ethane-acid, but this is very simple to remove (sodium bicarbonate etc.) and since this oxidation happens in stages, you will be able to get ethanal from this process.

No way, Jose. What is this "ethane-acid" business? I suppose you mean acetic acid, ethanoic acid or even vinegar. Again wine turns to vinegar, reasonably straight alcohol does not. By "reasonably straight" I am referring to concentrations above say 20%.

Acetaldehyde is made by oxidizing alcohol in the gaseous phase at high temperatures using a catalyst or by catalytically removing hydrogen, again in the gaseous phase and again at high temperatures. There are also individual processes for synthesizing the material from propane, butane, acetylene or ethylene, but it is NOT formed by letting alcohol stand.

The net very democratically offers everyone a chance to speak, but some are more qualified than others in certain areas. Tip's voice is no louder than yours in this forum, but he knows the subject material much better than you do. You have an opportunity to learn from him and a few other professionals and experienced practitioners in the art and science of pyrotechnics and explosives. Why spoil the opportunity with unjustified flames?

Jerry

From: (Gerald L. Hurst
Newsgroups: rec.pyrotechnics
Subject: Re: Re.: Re: Silver Cleaning
Date: 6 Nov 1995 22:55:51 GMT
Organization: Consulting Chemist

Im Artikel MalteK behauptet:

Im Artikel Gerald L.Hurst schreibt: I think Mr. Maltek is referring to the compound more commonly known as acetaldehyde. Ethanol (ethyl alcohol)can be oxidized to the aldehyde, which in turn can be further oxidized to acetic acid. The aldehyde is thus capable of acting as reducing agents and is sometimes used to convert silver salts to the metal (silvering mirrors).The conversion of ethanol (CH3CH2OH) to "ethanal" (CH3CHO)does not occur spontaneously. If it did, your vodka would soon smell strange. The reaction can be accomplished bypassing alcohol vapor over a hot metal catalyst. Jerry

why thank you Jerry, for giving me the time to show you that this post on your part is more than uncalled for.

I believe you mean "opportunity to show..." rather than "time to show..." The former has a better ring than the latter, but, of course, neither is factually correct. Rather, you now have another in a continuing series of opportunities to convince the forum that you are information proof. You enter discussions in ignorance and leave the same way, convinced of the truth of your assertions by the frequency of their repetition.

First of all, ethanal is the new nomenclature for acetaldehyde.

New? Not really. Chemists have been using the "al" ending to denote aldehydes since long before you were born. It merely so happens that they usually use more "user-friendly" names for the very common low molecular weight materials as well as for the very complex ones like vitamins, which would be a mouthful to pronounce if they used a structural name. I'll bet even you, Mr. Maltek, say "formaldehyde" instead of "methanal" and "aspirin" not "acetylsalicylic" acid. nicht wahr?

ethanol can be converted to ethanal,

True.

like I said,

False.

when you leave it to sit with the top OPEN.

Nope, it just evaporates and gathers water and dust.

Try it out, if you let it sit long enough it will even turn into ethane-acid, or whatever the English name for vinegar is under the new nomenclature.

The word you're looking for is "acetic acid." In German you call it "Essigsaeure" when you are not insisting on the Geneva conference name.

Quick! cork the 12-year old Wild Turkey before it turns to vinegar. And you thought Jack Daniels was joking when he said "sour mash." Just kidding. Have you forgotten that alcohol is an antiseptic? Unless you equip your bacteria with scuba gear they're going to have a tough time converting alcohol to vinegar. If fermentation processes worked at high alcohol concentrations (> ca 20%), we wouldn't need stills to make our likker.

As I and others have said before into your unreceptive ears, You can oxidize neat alcohol or remove hydrogen from it to produce acetaldehyde, but this is done via HOT, CATALYZED, VAPOR PHASE reactions or by sodium dichromate oxidation of the warm liquid, NOT by simple air oxidation at ambient temperatures. At room temperature with air you get ZIP, NADA, ZERO, ueberhaupt nichts, ganz und gar nichts, except contamination by dust and moisture and evaporation loss.

We all know that fermentation processes by microorganisms can convert carbohydrates to alcohol and acetic acid and produce various other organic materials, mostly of the headache-producing variety, including some aldehydes in suitably dilute and enzyme fortified solutions, but here we are talking not about fermentation but about direct chemical oxidation of ALCOHOL by air, and that simply does not happen to any measurable degree.

What you probably do not know is that yeasts produce acetaldehyde directly from carbohydrates and then REDUCE the aldehyde to form ethyl alcohol in wine and beer. We all know that beer and wine can be converted to vinegar by the aceter bacterium, but that doesn't mean you can tell the bacteria to produce and maintain a quantity of the aldehyde even in the dilute solutions which are not the topic of the original discussion.

The new name for vinegar is "vinegar." It (Essig) contains acetic acid, which you would call "ethanoic acid" if you had read the third page of the book from which you got the name "ethanal" on page two. If your text is German, you may use an "isch" ending instead of "ic" if it suits your fancy.

What a stupid Re, don't you have any common sense?

I don't know that I'm particularly gifted in that department, but I do seem to know a bit more about chemistry than some of the teeny bombers who post here. Actually, most of us in this group don't need to be too bright; we have enough young AOLers, et al to make us look good by comparison.

Jerry

P.S. For the record, I know very little about fermentation technology. If you don't like what you see here, inquire in sci,chem. They have a fellow over there (whose name eludes me) who really knows this subject. If you've read the above, you now know more about the subject than I do.

In fairness to Mr. Maltek, Let me report that I sent a preprint of this article to him and waited for his reply prior to posting. I added a few lines to reflect some of the points that were raised, including the previously unknown (to me) fact that Mr. Maltek's native language is German. I mention this only to explain the use of several simple German words by myself, as well as to let all know that the corrections in style were made before I knew that English is Mr. Maltek's second (or perhaps third or fourth) language:)

Some of you may ask what all this has to do with pyrotechnics. Other than the obvious flying spark, I don't know...

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