Stable polymorphic form of (E)-N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide and the process for its preparation

  • US 5,135,950 A
  • Filed: 10/31/1990
  • Issued: 08/04/1992
  • Est. Priority Date: 11/03/1989
  • Status: Expired due to Term
First Claim
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1. The crystallographically essentially pure polymorphic form A of (E)-N,N-diethyl-2-cyano-3-(3,4dihydroxy-5-nitrophenyl)acrylamide having the infrared spectrum in potassium bromide having the following absorption bands:

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    space="preserve" listing-type="tabular">______________________________________ Wave numbers Wave numbers (cm.sup.-1) (cm.sup.-1) ______________________________________ 3339 1512 3092 1441 3066 1377 3039 1298 2981 1281 2938 1210 2217 1165 1628 1150 1607 800 1580 779 1544 740 ______________________________________

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