Wood vinegar

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Wood vinegar - also called wood acid (from Latin Acetum lignorum or also Acidum pyrolignosum ) - is the brown, sour and pungent , watery liquid ( smoldering water ) that smells and tastes like charcoal and the organic substances dissolved in it that occur during the dry distillation of wood whose main component is acetic acid .

properties

Wood vinegar from spec. . Wt from 1.015 to 1.03, consisting of about: 12% acetic acid and homologs , 2% methanol , 1% acetone , 1% methyl acetate and 10% dissolved tar (Brand oil Pyrrelin and fire resins Pyrdain ), the rest is water with traces of Butyric acid , phenol (carbolic acid), acetaldehyde and ammonium salts .

Manufacturing

In the pyrolysis of wood approximately 20-30% is produced coal , 30-40% wood vinegar, wood tar 10-15%, 10-15% wood gas , the distillation products are partly gases, partly vapors by cooling templates again form droplets condensed are depending on Volatility results in wood vinegar and wood tar , which occupies the lower position in the distillate.

When wood is charred in the traditional way in charcoal piles, in addition to water vapor, the wood gases and wood vinegar partially escape into the air and burn. In contrast, single-chamber (pitch ) and two-chamber ( retort ) ovens use the distillation process, which produces more wood vinegar and tar . The gas that occurs is partially used, it is fed back and burned as well (see also charcoal ).

By far the largest amount of wood vinegar was processed into acetic acid, the old name for acetic acid was wood acid . Originally, the acetic acid was neutralized and bound by adding milk of lime to the distillate . This resulted in gray lime or acetic lime , which contained up to 83% calcium acetate . By displacement with hydrochloric acid so-called until an acid reaction was Braunkalk obtained. The neutralization of the retort gases with milk of lime provided so-called black lime . The crude acetic acid obtained through acid treatment then had to be freed from the by-products of wood pyrolysis by rectification . In newer processes, the representation is done directly from the vapors ( Suida process ), the distillate ( azeotropic distillation ) or the extraction with ether or with wood tar oils .

When processing raw wood vinegar , tar is produced. The higher the content of acetic acid and wood spirit, the greater the amount of tar dissolved in it. When separating the wood spirit from the wood vinegar, Büttentar (lignin tar) is produced; during vacuum distillation it is extraction tar . As an alternative to distillation, the raw wood vinegar can also be freed from tar by washing the vapors with oils.

The wood vinegar obtained in this way still contains wood spirit and acetone as by-products. After acetone has been separated off by converting it into a crystalline compound with calcium chloride , the wood spirit settles on top. For wood alcohol, the names exist in this context Methyloxydhydrat , methyl alcohol , carbinol , methanol , wood alcohol , wood alcohol , and Methylenbihydrat Holznaphtha.

Holzgeist is a mixture of around 45% methanol , 7% acetone, 5% methyl acetate , 3% acetaldehyde , 1% allyl alcohol . Holzgeist is a colorless, slightly spiritual smelling liquid, with a boiling point of 66 ° C and a density of 0.796 g · cm −3 . It used to be processed on methanol ( wood alcohol , wood spirit ). The production of wood spirit was used in the 19th century, since with wood spirit less volume could be transported with easier handling. Most of the acetic acid contains the distillate of beech and birch wood, hardwoods produce more vinegar and tar than conifers. In general the content varies between 5% and 9% acetic acid. The mass production of acetic acid and wood spirit was on a large scale at the end of the 19th century.

use

The wood vinegar is used as a rot-inhibiting coating , insecticide , for preserving wood and ropes , as well as meat products (cold smoking). In veterinary medicine, it is used for foot-and-mouth disease , mange , scabies , and also as an external medicine for wounds. In dye works and printing works, raw wood vinegar was used to produce the acetic and wood acid iron required by certain colors . It is also used instead of ordinary vinegar for the production of lead sugar , acetic acid clay ( aluminum diacetate ) and other preparations.

The purified or rectified wood vinegar is obtained by redistilling the raw wood vinegar. This is used in medicine ( Acetum pyrolignosum rectificatum ). However, it is not yet pure vinegar, it still smells sticky and loses its initial colorlessness again under the influence of air and light, since the wood tar still contained is colored by oxygen absorption and makes the liquid appear yellowish or brownish.

literature

  • Max Klar: Technology of charring and the manufacture of acetic acid, acetone, methyl alcohol and other wood distillates. Springer-Verlag, 1903, ISBN 978-3-642-98495-2 .

Individual evidence

  1. ↑ Hans-Georg Elias: Macromolecules. Volume 3: Industrial polymers and syntheses, 6th edition, Wiley-VCH, 2009, ISBN 978-3-527-29961-4 , doi: 10.1002 / 9783527626519 .
  2. ^ Gerhard Eisenbrand, Peter Schreier: Römpp Lexikon Lebensmittelchemie. A-L . 2nd Edition. Georg Thieme Verlag, 2006, ISBN 978-3-13-179532-8 , p. 160.
  3. ↑ Wood vinegar . In: Meyers Großes Konversations-Lexikon . 6th edition. Volume 9, Bibliographisches Institut, Leipzig / Vienna 1907, pp.  502–504 .
  4. ↑ a b c d e wood vinegar . In: Meyers Konversations-Lexikon . 4th edition. Volume 8, Verlag des Bibliographisches Institut, Leipzig / Vienna 1885–1892, pp. 679–680.
  5. ↑ Hans Irion: Drogisten-Lexikon. 2. Volume A-K . Springer, 1955, ISBN 978-3-642-92641-9 , p. 428.
  6. ^ Fritz Ullmann: Encyclopedia of Technical Chemistry . Volume 6. 2nd edition. Urban & Schwarzenberg, 1930, p. 187, Textarchiv - Internet Archive
  7. ^ Bernhard Neumann: Textbook of chemical technology and metallurgy. 3. Edition. Springer, 1939, ISBN 978-3-642-90199-7 , p. 221.
  8. ↑ Dieter Osteroth: Biomass: Return to the ecological balance. Springer, 1992, ISBN 978-3-642-77410-2 , p. 110.
  9. ↑ Ernst Bartholomé (Ed.): Ullmanns Encyklopadie der technischen Chemie. Volume 17. Verlag Chemie, 1979, ISBN 978-3-527-20000-9 , p. 704.
  10. ↑ Calisto Bianchi, Adolf Weihe: Cellulose ester lacquers. Springer-Verlag, 1931, ISBN 978-3-662-38990-4 , p. 79.
  11. ^ Otto Lueger : Lexicon of the entire technology and its auxiliary sciences. Volume 5. Stuttgart / Leipzig 1907, p. 115
  12. ^ L. Elsner: The chemical-technical communications of the latest time. Volume 23, Julius Springer, Berlin 1875, pp. 59, 60, babel.hathitrust.org, accessed on January 12, 2017.