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Acidic wash - Ethyl Acetate ?

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  • Ackland, Tony (CALBRIS)
    I recently had the following information forwarded to me. Any comments from the pro-acid or pro-bicarb camps ? Tony
    Message 1 of 2 , Nov 25, 2004
      I recently had the following information forwarded to me.
      Any comments from the pro-acid or pro-bicarb camps ?
      Tony
      **********************************************************************************
      Tony,
      I recently came across some information that I thought was very interesting, but is not contained on your website, at least not with the scientific support:
      I have found that Ethyl Acetate is the most difficult byproduct to exclude from distillate for a number of reasons:
      Unlike methanol it is a natural product of fermentation and exists in larger quantities.
      Its boiling point is very close to ethanol
      Its got a particularly nasty smell and taste
      Whilst its a product of the reaction between ethanol and acetic acid, this reaction requires the acidic environment of the wash to occur. Without an acidic environment ethyl acetate reacts with water, decomposing back into ethanol and acetic acid. As you are no doubt aware, acetic acid is much easier to remove by distillation with its boiling point of 118 degrees C.
      See <http://cavemanchemistry.com/cavebook/chsoap2.html>
      Your site makes a number of references to the use of baking powder improving distillation - this may provide some scientific justification to these claims, although there is still the need to avoid ammonia salt decomposition and it is not recommended for a first distillation.
      I prefer to use simple aeration with an air stone. I had noticed the marked improvement in taste and odour resulting from vigorously aerating kept heads and tails and sought to find an explanation. It appears that decomposition is a naturally occuring process and is simply sped up by the agitation of aeration (and without the use of baking soda).


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    • Harry
      ... ********************************************************************* ... interesting, but is not contained on your website, at least not with ... in
      Message 2 of 2 , Nov 25, 2004
        --- In Distillers@yahoogroups.com, "Ackland, Tony \(CALBRIS\)"
        <Tony.Ackland@c...> wrote:
        > I recently had the following information forwarded to me.
        > Any comments from the pro-acid or pro-bicarb camps ?
        > Tony
        >
        *********************************************************************
        *************
        > Tony,
        > I recently came across some information that I thought was very
        interesting, but is not contained on your website, at least not with
        the scientific support:
        > I have found that Ethyl Acetate is the most difficult byproduct to
        exclude from distillate for a number of reasons:
        > Unlike methanol it is a natural product of fermentation and exists
        in larger quantities.
        > Its boiling point is very close to ethanol
        > Its got a particularly nasty smell and taste
        > Whilst its a product of the reaction between ethanol and acetic
        acid, this reaction requires the acidic environment of the wash to
        occur. Without an acidic environment ethyl acetate reacts with
        water, decomposing back into ethanol and acetic acid. As you are no
        doubt aware, acetic acid is much easier to remove by distillation
        with its boiling point of 118 degrees C.
        > See <http://cavemanchemistry.com/cavebook/chsoap2.html>
        > Your site makes a number of references to the use of baking powder
        improving distillation - this may provide some scientific
        justification to these claims, although there is still the need to
        avoid ammonia salt decomposition and it is not recommended for a
        first distillation.
        > I prefer to use simple aeration with an air stone. I had noticed
        the marked improvement in taste and odour resulting from vigorously
        aerating kept heads and tails and sought to find an explanation. It
        appears that decomposition is a naturally occuring process and is
        simply sped up by the agitation of aeration (and without the use of
        baking soda).



        Well Tony, I won't pretend that I know all the "in's & out's" of
        this, but a few things come to mind. Old stillmen used to
        neutralise the wash before distilling, for this very reason.
        However, as I discovered on one occasion, neutralising can lead to
        blue distillate if you are using copper in your still (not
        dangerous, just requires cleanup). This is because you need to very
        carefully monitor the process, as you are adding alkali substances
        which react with the copper. A little too much and you will overdo
        it and get a pretty blue result.

        As to the close boiling points, this is not 'quite' correct. In
        pure form, yes, but we are talking about mixtures here, namely
        acetate/alcohol/water, a 'ternary' mixture (in reality, the wash
        contains far more that 3 items, but let's concentrate on those
        three).

        I have figures from a laboratory in Montana that studied this very
        mixture. This is what they have to say...

        Acetate/alcohol/water ternary mixtures are found in the manufacture
        of acetates, in some waste solvent or process streams, and in
        laboratory preparations. Typically, these acetate/alcohol/water
        ternary systems are complex mixtures in that they often contain
        combinations of binary and ternary azeotropes. To illustrate this
        complexity, Table 1. provides boiling point and azeotrope
        compositional data for the ethyl acetate/ethanol/water system.



        Compound(s)...... BP - oC...... Azeotrope Composition ( %)
        .............................Ethanol...Ethyl Acetate... Water

        Ethanol.......... 78.3

        Ethyl acetate.... 77.1

        Water............ 100

        Ethanol/water.... 78.2 ...... 95.4 ..... ----------- ... 4.6

        Ethyl acetate/water
        ................. 70.4 ...... ---- ..... 91.9 ........ 8.1 (2 phases)

        Ethanol/ethyl acetate
        ................. 71.8 ...... 31 ....... 69 .......... ----- .

        Ethanol/
        ethyl acetate/
        water........... 70.2 ....... 8.4 ...... 82.6 ........ 9.0


        From this you can clearly see the BP of the mixture we are
        discussing is 70.2 degC, which is well below our ethanol/water
        binary mixture of 78.2 degC. In other words, there's no reason why
        a carefully controlled distillation wouldn't remove all acetate with
        the first heads portion (unless one were too greedy).

        As to the aeration of salvaged heads/tails before re-distillation,
        yes this is probably a good idea as it will eliminate some of
        the 'nasties' as a natural process, just as the message author has
        discovered. It certainly can't hurt.


        HTH
        Slainte!
        regards Harry

        ps
        The Montana company and it's studies can be found here...

        Dr. Lloyd Berg, Chairman and Director of Research, Brix-Berg Company
        PLLC. Emeritus Department Head and Professor, Chemical Engineering
        Department, Montana State University and

        A. Terry Brix, President, Brix-Berg Company PLLC

        http://www.brix-berg.com/study4.htm
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