The good news is as follows
The Boiling point of Acetic Acid is 118.1 °C (391.2 K)(244.6 °F).
The boiling point of water is 100 °C
This tells me you can boil vinegar and (provided you can keep the
vinegar below 118°C) after the water has boiled off you will be left
with a higher concentration of Acetic Acid.
The melting point of Acetic Acid is 16.7 °C (289.9 K)(62.1 °F)
(obtained from http://en.wikipedia.org/wiki/Acetic_acid )
Which tells me you can safely put vinegar into a fridge or freezer
(most probably the fridge) where the temperature is kept below 16.7
degrees and above 1 degree. The Acetic Acid will solidify into a white
crystaline powder allowing you to extract it and use for your
purposes, you must note however that as the melting point is 16.7
degrees you can't scoop it out with your fingers as you are roughly 37
degrees in temperature. Acetic acid is also VERY soluable in water so
may not completely solidify.
This website gives you a good overview of how Acetic Acid was
extracted in the 17th and 18th centuries. After reading this though
you may realise that extracting Acetic Acid from vinegar may not be as
easy as it sounds.
"In 1697 Stahl showed that vinegar could be concentrated by freezing
out part of the water, and, better, in 1702, by neutralizing the acid
with an alkali and distilling the salt with oil of vitriol. A notable
improvement was made in 1789 by Lowitz, who showed that the dilute
acid could be concentrated by repeatedly passing it over charcoal
powder and by cooling he obtained a crystalline substance named in
1777 by Durande, "glacial acetic acid.""
In summary you have two easy main options and some harder ones, you
can either boil the vinegar and keep the temperature below 118 degrees
and above 100 degrees, or cool vinegar and keep the temperature below
16 degrees and above 5 degrees (to be safe) or you can follow the
works of Stahl and neutralise the vinegar with baking soda and
distilling it with oil of vitriol.
I would believe the cooling option is your easiest and most successful.
I must advise you though that household vinegar is not just Acetic
acid and water, it also contains other chemicals within it too.
It may be easier to purchase the substance directly from one of the
If you are willing to venture to companies to buy it directly this
company may be able to sell it to you directly at 84 - 97%
Your best option to purchase this would be to speak to a friend who
works for a school or a university or speak to a university directly
and ask where they get their chemicals from and purchase yours from
the same companies.
I hope this answers your question.