Pharmaceutisch Weekblad

, Volume 10, Issue 2, pp 90–92 | Cite as

Titrimetric determination of acetylenic hypnotics using organic brominating agents

  • A. El-Brashy
  • F. Belal
  • M. I. Walash
  • M. Rizk
Short Communications


A titrimetric method is described for the determination of three acetylenic hypnotics, namely ethchlorvynol, ethinamate, and methylpentynol carbamate, in bulk and in dosage forms. The method involves the use of either 1,3-dibromo-5,5-dimethylhydantoin (DBH),N-bromosuccinimide (NBS) orN-bromophthalimide (NBP) as titrants. A known excess volume of the reagent is added and, after the specified time, the residual reagent is determined iodometrically. This procedure permits semimicro determination (1–15 mg) of the drug. The procedure has been successfully applied to pharmaceutical dosage forms; the results agree well with those given by compendial methods. The stoichiometry of the reaction has been assessed and an explanation of the reaction pathway is presented.


Brominating agents Ethchlorvynol Ethinamate Methylpentynol Titrimetry 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Rutledge TF. Acetylenic compounds, preparation and substitution reactions, New York: Reinhold Book Corporation, 1968:314–33.Google Scholar
  2. 2.
    British Pharmacopoeia. London: Her Majesty's Stationery Office, 1973;191.Google Scholar
  3. 3.
    The United States Pharmacopoeia xx, National Formulary xv. Rockville: USP Convention, Inc., 1980:306.Google Scholar
  4. 4.
    Rizk M, Walash MI, El-Brashy A. Titrimetric determination of acetylenic hypnotics using ion selective electrode. J Assoc Off Anal Chem 1982;65:138–40.Google Scholar
  5. 5.
    Bridges RR, Jennison TA. Analysis of ethchlorvynol. J Anal Toxicol 1984;8:263–8.Google Scholar
  6. 6.
    Rizk M, Walash MI, El-Brashy A. Colorimetric determination-of acetylenic hypnotics by formation of silver acetylides. J Assoc Off Anal Chem 1980;63: 88–90.Google Scholar
  7. 7.
    French WN. Identification of ethinamate, ethchlorvynol and methylparafynol. J Pharm Sci 1964;53:842–4.Google Scholar
  8. 8.
    Rizk M, Walash MI, El-Brashy A. Spectrophotometric determination of methylpentynol carbamate. Freseniusz Anal Chem 1982;310:256.Google Scholar
  9. 9.
    Walash MI, Rizk M, El-Brashy A. Ultraviolet and fluorometric determination of acetylenic hypnotics after conversion to their carbonyl derivatives. Anal Lett 1982;15:963–80.Google Scholar
  10. 10.
    Gibson PF, Wright N. Ethchlorvynol in biological fluids: specificity of assay method. J Pharm Sci 1972;61:169–71.Google Scholar
  11. 11.
    Perrigo BJ, Peel HW, Ballantyne DJ. Gas chromatographie determination of ethinamate. J Chromatogr 1985;341:81–8.Google Scholar
  12. 12.
    Walash MI, Rizk M, Belal F, Abou-Ouf AA. Evaluation of certain pharmaceuticals with dibromohydantoin; 2-determination of analgesics. Pharmazie 1979;34:224–6.Google Scholar
  13. 13.
    Rizk M, Walash MI, Abou-Ouf AA, Belal F. Evaluation of certain pharmaceuticals with dibromohydantoin. v. Determination of penicillins. Anal Lett 1981;14:1407–17.Google Scholar
  14. 14.
    Abou-Ouf AA, Walash MI, Salem FB. Spectrophotometric and titrimetric determination of catecholamines using organic brominating agent. Analyst 1981;106:949–54.Google Scholar
  15. 15.
    Walash MI, Rizk M, Abou-Ouf AA, Belal F. Titrimetric determination of someN-substituted phenothiazine derivatives. Analyst 1983;108:626–32.Google Scholar
  16. 16.
    Walash MI, Rizk M, Abou-Ouf AA, Belal F. Determination of some quinoline derivatives with organic brominating agents. Anal Lett 1983;16:129–48.Google Scholar
  17. 17.
    Mathur NK, Narang CK. Determination of organic compounds withN-bromosuccinimide and allied reagents. London: Academic Press, 1974.Google Scholar
  18. 18.
    Hinchen JD. Practical statistics for chemical research. London: Methuen, 1969:22.Google Scholar
  19. 19.
    Muller K. Functional group determination of olefinic and acetylenic unsaturation. London: Academic Press, 1975;317.Google Scholar

Copyright information

© Royal Dutch Association for Advancement of Pharmacy 1988

Authors and Affiliations

  • A. El-Brashy
    • 1
  • F. Belal
    • 1
  • M. I. Walash
    • 1
  • M. Rizk
    • 1
  1. 1.Faculty of Pharmacy, Department of Analytical ChemistryMansoura UniversityMansouraEgypt

Personalised recommendations