RE: Preparation of formamidinesulfinic acid - Orglist Synthetic Letters

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From: Cesar Barbero (cbarbero$##$exa.unrc.edu.ar)
Date: Thu Mar 08 2001 - 05:59:36 EST


Great Idea.
By the way. If you have other procedures for preparation of aliphatic =
and/or aromatic sulphinic acids, they would be most appreciated.
Best Regards


  ----- Original Message -----
  From: Jiri Janovsky
  To: Multiple recipients of list orglist
  Sent: Wednesday, March 07, 2001 3:51 PM
  Subject: Preparation of formamidinesulfinic acid - Orglist Synthetic =
Letters


  Dear colleagues :
  I kindly suggest to establish The Orglist Synthetic Letters, where =
simple and facile preparations of the important organic or inorganic =
compounds would be presented. The following synthesis is the first =
contribution into the forum. This is the original translation from the =
czech hanbook published in 1972. The full citation is mentioned below. =
Your comments are cordially welcomed.

  Preparation of formamidinesulfinic acid
  116 g of 30 % hydrogen peroxide weight out in a beaker on accurate =
technical balance. Pour the hydrogen peroxide into a 1000 ml beaker and =
dilute it with 600 ml of distilled water. Place the beaker into a large =
vessel (e.g. enameled pot) and encase it with a mixture of gently =
grinded ice and sodium chloride. Place the glass stirrer powered with =
electric motor into the liquid and under continuing mixing allow the =
solution to cool down to 5 C. Then, during two hours, under the =
continuing intensive mixing, add with spoon small doses of 38 g gently =
pulverized thiourea. The temperature during this process should be =
between 5 and 20 C. Refresh the coolant if necessary. When all amount =
of thiourea is added continue with cooling of the mixture with ice and =
sodium chloride for next 1 hour. Then cool down all mixture close to =
freezing point. Filter the separated formamidinesulfinic acid preferably =
with small glass frit. Wash obtained product with small quantity of icy =
water and then with small portion of methanol. Washed acid is dried up =
in vacuum desiccator upon anhydrous calcium chloride.

  Characteristics:
  Formamidinesulfinic acid forms the colorless fine needles with melting =
point 144 C. Formamidinesulfinic acid is slightly soluble in water. =
Saturated solution contains about 3 % of the acid and pH is about 5. It =
is soluble in acetic acid without decomposition. For its reducing =
properties the acid is useful in industry. Its ammoniacal solution =
rapidly absorbs the oxygen.

  Reference:
  Klikorka J., Klazar J., Votinsky J., Horak J.: Introduction into =
Preparative Inorganic Chemistry, SNTL Publishers, Prague 1972, page 188 =
(in Czech).

  Next: Chemical properties of thiourea-dioxide.

  With love,
  J.Janovsky
  Institute of Chemical Technology
  Department of Physical Chemistry
  5 Technical Street
  Prague, CZ 16628
  Czech Republic



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