Newsgroups: sci.chem
Subject: Re: White vinegar
From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Date: Fri, 11 Apr 1997 19:24:49 GMT

Eric Lucas <ealucas*antispam*@ix.netcom.com> 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
>> colour 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 tradionally 
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: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: rec.pyrotechnics
Subject: Re: Re.: Re: Silver Cleaning
Date: 5 Nov 1995 23:15:46 GMT

In article <47janv$eg6@newsbf02.news.aol.com>, maltek@aol.com (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 (sodiumbicarbonate
>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
ethlylene, 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 practioners in the art and 
science of pyrotechnics and explosives. Why spoil the 
opportunity with unjustified flames?  

Jerry

From: glhurst@onr.com (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 <47jao0$eg8@newsbf02.news.aol.com>, maltek@aol.com (MalteK) 
behauptet:

>Im Artikel <46sdq7$l5o@geraldo.cc.utexas.edu>, glhurst@onr.com (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 by
>>passing 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
coursen, 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'r 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 
teenybombers 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.