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Organic : creating vinegar
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Message 1 of 14 in Discussion

From:

N_2006 (Original Message)

Sent: 10/24/2006 1:08 AM

I need some help with writing chemical equations that show the reactions that produce vinegar from ethanol.

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Message 2 of 14 in Discussion

From:

·Steve·

Sent: 10/24/2006 7:22 AM

Hi Natalina, also been a while, hope you're doing OK!

>> I need some help with writing chemical equations that show the reactions that produce vinegar from ethanol. <<

The oxidation of ethanol first gives acetaldehyde, followed by further oxidation to acetic acid (actually acetate ion at physiological pH). Vinegar is about 5% acetic acid in water, by weight.

From http://www.elmhurst.edu/~chm/vchembook/642alcoholmet.html:
The first step in the metabolism of alcohol is the oxidation of ethanol to acetaldehyde catalyzed by alcohol/dehydrogenase containing the coenzyme NAD⁺. The acetaldehyde is further oxidized to acetic acid and finally CO2 and water through the citric acid cycle. A number of metabolic effects from alcohol are directly linked to the production of an excess of both NADH and acetaldehyde.

CH3CH2OH + NAD⁺ ––�?gt; CH3CH=O + NADH + H⁺

From http://www.chemcases.com/alcohol/alc-06.htm:
Another system in the liver which oxidizes ethanol via the enzyme cytochrome P450IIE1 (CYP2E1) is called the MEOS system. The reaction catalyzed by MEOS is:

CH3CH2OH + NADPH + O2 ––�?gt; CH3CHO + NADP⁺ + H2O.

From http://web.indstate.edu/thcme/mwking/glycolysis.html#ethanol:
Animal cells (primarily hepatocytes) contain the cytosolic enzyme alcohol dehydrogenase (ADH) which oxidizes ethanol to acetaldehyde. Acetaldehyde then enters the mitochondria where it is oxidized to acetate by acetaldehyde dehydrogenase (AcDH).

CH3CHO + NAD⁺ (+ H2O) ––�?gt; CH3COOH + NADH + H⁺

The same reactions are also given at http://chemcases.com/alcohol/index.htm.
(Has general information about ethanol and its effects on the body, kind of interesting.)

Steve

Message 3 of 14 in Discussion

From:

·Steve·

Sent: 10/24/2006 9:06 PM

Here are the oxidations using dichromate ion, a commonly used oxidizing agent in organic chemistry:

Partial oxidation to aldehydes
3 CH3CH2OH + Cr2O7^{2�?/SUP> + 8 H⁺ ––�?gt; 3 CH3CHO + 2 Cr³⁺ + 7 H2O}

Full oxidation to carboxylic acids
3 CH3CH2OH + 2 Cr2O7^{2�?/SUP> + 16 H⁺ ––�?gt; 3 CH3COOH + 4 Cr³⁺ + 11 H2O}

From http://www.chemguide.co.uk/organicprops/alcohols/oxidation.html

Steve

Message 4 of 14 in Discussion

From:

N_2006

Sent: 10/24/2006 10:05 PM

Hey Steve,

Yes I'm doing well, its been a while, How are you?
I've been busy with Calculus, and speaking of which do you know any sites that are good for calculus just like this one?
And thanks for the help with the vinegar... I'm doing an experiment with it and needed some guidance with the equations...
Thanks
Natalina

Message 5 of 14 in Discussion

From:

·Steve·

Sent: 10/25/2006 12:24 AM

I've been doing OK, thanks, just the same ol' stuff!

We found a few math groups from your earlier post here; the last two looked like good ones, might give one a try. Good luck!

Steve

Message 6 of 14 in Discussion

From:

N_2006

Sent: 11/12/2006 8:25 PM

Hey...
Thanks for those math websites...
Just another question about this Vinegar...
I am doing an experiment that involves creating vinegar from apples, by letting them ferment and now i need to show a chemical equation for that..
Would this be correct?
You start of with ethanol.. ( I think so) and then that goes through a controlled oxidiztaion (because I am controlling how much oxygen I am letting in per day) and then doesnt' that produce a ketone?

Thanks

Message 7 of 14 in Discussion

From:

·Steve·

Sent: 11/13/2006 6:49 AM

We can write an overall chemical reaction going from ethanol to acetic acid using only O2 as the oxidizing agent by adding the following reactions:

CH3CH2OH + O2 + 2 H⁺ ––�?gt; CH3CHO + 2 H2O
CH3CHO + O2 + 2 H⁺ ––�?gt; CH3COOH + H2O

to give

CH3CH2OH + 2 O2 + 4 H⁺ ––�?gt; CH3COOH + 3 H2O

Enzymes in the bacteria mentioned below would catalyze these reactions.

You shouldn't get a ketone from ethanol because the simplest ketone (acetone) has three carbons but your starting compound ethanol has only two carbons. Therefore any oxidation product of ethanol alone will also have only two carbons.

I didn't know there was so much on the Internet about making vinegar - Here's one site:
http://www.naturemoms.com/homemade-vinegar.html

From http://www.findarticles.com/p/articles/mi_m0GCU/is_n6_v14/ai_20152545:
Apple cider vinegar is made by crushing apples and squeezing out the liquid. Sugar and yeast are added to the liquid to start the fermentation process, which turns the sugars into alcohol. In a second fermentation process, the alcohol is converted by acetic acid-forming bacteria into vinegar. Acetic acid gives vinegar its sour taste.

Steve

Message 8 of 14 in Discussion

From:

·Steve·

Sent: 11/13/2006 5:10 PM

I forgot about charge balancing the equations - as written they are not. Here we go again:

CH3CH2OH + 1/2 O2 ––�?gt; CH3CHO + H2O

CH3CHO + 1/2 O2 ––�?gt; CH3COOH

When these are added together we have

CH3CH2OH + O2 ––�?gt; CH3COOH + H2O

That's more like it!

Steve

Message 9 of 14 in Discussion

From:

N_2006

Sent: 11/13/2006 9:05 PM

Hey
Thanks for the great info and help...
What about the enzymes.. you said they were listed below??

Also as I'm writing this lab up I'm having trouble coming up with some sort of table I could use for my observations... Any suggestions?
I thought og creating a table that goes in increments of 4 to 5 days... and looking at the change in colour, the smell, any sediment, and whatever else I noted.
But that just doesn't seem the greatest idea for a table... any help would b appreciated...
Thanks again so much

Message 10 of 14 in Discussion

From:

·Steve·

Sent: 11/14/2006 3:29 AM

The Wikipedia article on acetaldehyde gives the general names of the enzymes that catalyze the oxdiation of ethanol in the liver - alcohol dehydrogenase and acetaldehyde dehydrogenase. Alcohol dehydrogenase catalyzes the oxidation of alcohols to aldehydes:

RCH2OH + NAD⁺ ––�?gt; RCHO + NADH + H⁺

Alcohol dehydrogenase is also found in yeast.

Aldehyde dehydrogenases oxidizes aldehydes to carboxylic acids:

RCHO + NADP⁺ + H2O ––�?gt; RCOOH + NADPH + H⁺

NADH⁺ = nicotinamide adenine dinucleotide

NADP⁺ = nicotinamide adenine dinucleotide phosphate

(See http://en.wikipedia.org/wiki/NADH)

The observations you are monitoring sound OK to me. If you can, a good thing to also monitor is the pH of the solution. The more acetic acid that is formed, the lower the pH will become.

Steve

Wikipedia article on acetaldehyde:

http://en.wikipedia.org/wiki/Acetaldehyde

Message 11 of 14 in Discussion

From:

N_2006

Sent: 11/14/2006 3:40 AM

Alright thanks

Yeah i thought of using litmus to test it, but now my experiment is over, so its a little to late, but that was a good idea.

Its just not an experiment where there are exact values or anythign so it seems difficult to come up with some sort of chart, or graph.

Thanks... sure i'll be talking to u soon with more questions!

Message 12 of 14 in Discussion

From:

·Steve·

Sent: 11/14/2006 8:41 AM

OK, hope it turned out OK! Yes, for accurate pH measurements a pH meter would have been best, which may not have been available. Oh well!

Message 13 of 14 in Discussion

From:

N_2006

Sent: 11/17/2006 7:38 PM

Hey Steve..
The experiment did go well... I did create vinegar.. just awaiting on my lab report mark.. Thanks sooo much for your help

Message 14 of 14 in Discussion

From:

·Steve·

Sent: 11/18/2006 7:14 AM

You're quite welcome, sounds good!

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