Rosocyanine

Rosocyanine and borates.

Application

The color reaction between pH values, interferencing with other compounds.

Rosocyanine is formed as 2 : 1-complex from curcumin and boric acid in acidic solutions. Curcumin possesses a 1,3-chelating agent. The formed boron complexes are called dioxaborines (here a 1,3,2-dioxaborine). The structural formula 1 given for rosocyanine (a cationic dicurcuminatoboron complex, here written with chloride as counter ion) is idealized. Investigations on the structure show that the positive charge is distributed all over the molecule, and therefore a structure as indicated in formula 2 rather describes the molecule condition. In rosocyanin the two curcumin molecules halves are not plain within the same level, but are twisted against each other. The same applies to rubrocurcumin.

In order to exclude the disturbing presence of other materials during the boron quantification using the curcumin method, a variant was developed. 2,2-Dimethyl-1,3-hexanediol or 2-ethyl-1,3-hexanediol are added, in addition to curcumin, to a neutral solution of the boron-containing solution. The formed complex between boron and the 1,3-hexanediol derivate, is removed from the aqueous solution by extraction in an organic solvent. After acidifying the organic phase, rubrocyanine is formed, which could be measured by colorimetric methods. The reaction of curcumin with borates in presence of oxalic acid therefore produces the coloring material rubrocurcumin.

Characteristics

Rosocyanine - [sum formula [B(C₂₁H₁₉O₆)₂]Cl, here given as chloride] - is a dark-green colored solid with glossy-metallic shine, forming red colored solutions. In water and some organic solvents it is almost insoluble, in alkali.

In rubrocurcumin one molecule curcumin is replaced with oxalic acid. Rubrocurcumin produces a similar red colored solution.

Rosocyanine is build from ions, while rubrocurcumin is a neutrally charged composition.

See also

• Curcuminoids

References

• M. E. Schlumberger: Sur la réaction de l'acide borique sur la curcumine. In: Bulletin de la Société Chimique de Paris N.S. 5, p. 194-202 (1866), ISSN: 0991-6504.
• L. Clarke and C. L. Jackson: Rosocyanine. In: American Chemical Journal Vol. 39, p. 696-719 (1908); ISSN: 0096-4085, CODEN: ACJOAZ.
• G. P. Spicer and J. D. H. Strickland: Compounds of curcumin and boric acid. Part I. The structure of rosocyanine. In: Journal of the Chemical Society (London), p. 4644-4650 (1952). ISSN: 0368-1769, CODEN: JCSOA9.
• G. P. Spicer and J. D. H. Strickland: Compounds of curcumin and boric acid. Part II. The structure of rubrocurcumin. In: Journal of the Chemical Society (London), p. 4650-4653 (1952). ISSN: 0368-1769, CODEN: JCSOA9.
• L. J. Bellamy, G. P. Spicer and J. D. H. Strickland: Compounds of curcumin and boric acid. Part III. Infra-red studies of rosocyanine and allied compounds. In: Journal of the Chemical Society (London), p. 4653-4656 (1952). ISSN: 0368-1769, CODEN: JCSOA9.
• G. P. Spicer and J. D. H. Strickland: Determination of microgram and submicrogram amounts of boron. I. Absorptiometric determination with curcumin. In: Analytica Chimica Acta Vol. 18, p. 231-239 (1958); ISSN: 0003-2670, CODEN: ACACAM.
• H. J. Roth and B. Miller: Zur Kenntnis der Farbreaktion zwischen Borsaeure und Curcumin, I. In: Archiv der Pharmazie, Berichte der Deutschen Pharmazeutischen Gesellschaft Vol. 297, No. 10, p. 617-623 (1964); ISSN: 0376-0367, CODEN: APBDAJ.
• H. J. Roth and B. Miller: Zur Kenntnis der Farbreaktion zwischen Borsaeure und Curcumin, II. In: Archiv der Pharmazie, Berichte der Deutschen Pharmazeutischen Gesellschaft Vol. 297, No. 11, p. 660-673 (1964); ISSN: 0376-0367, CODEN: APBDAJ.
• Fritz Umland, Detlef Thierig and Gunther Mueller: Photometrische Bestimmung von Bor im Picogram-Bereich. In: Fresenius Journal of Analytical Chemistry Vol. 215, No. 5, p. 401-406 (1966); ISSN: 0937-0633, CODEN: FJACEP.
• P. Quint and F. Umland: On the composition of the (1 2)-boron-curcumin-chelate »rosocyanine«. In: Fresenius Journal of Analytical Chemistry Vol. 295, No. 4, p. 269-270 (1979); ISSN: 0937-0633, CODEN: FJACEP.
• David W. Dyrssen, Yu. P. Novikov and Leif R. Uppstrom: Chemistry of the determination of boron with curcumin. In: Analytica Chimica Acta Vol. 60, No. 1, p. 139-151 (1972); ISSN: 0003-2670, CODEN: ACACAM.
• C. G. Kowalenko and L. M. Lavkulich: A modified curcumin method for boron analysis of soil extracts. In: Canadian Journal of Soil Science Vol. 56, No. 4, p. 537-539 (1976); ISSN: 0008-4271, CODEN: CJSSAR.
• Ulrike de la Chevallerie-Haaf, Axel Meyer and Guenter Henze: Photometrische Bestimmung von Bor im Grund- and Oberflächenwasser. In: Fresenius Journal of Analytical Chemistry Vol. 323, No. 3, P. 266-270 (1986); ISSN: 0937-0633, CODEN: FJACEP.
• Elsie M. Donaldson: Spectrophotometric determination of boron in iron and steel with curcumin after separation by 2-ethyl-1,3-hexanediol-chloroform extraction. In: Talanta Vol. 28, No. 11, p. 825-831 (1981); ISSN: 0039-9140, CODEN: TLNTA2.
• B. Wikner: Boron determination in natural waters with curcumin using 2,2-dimethyl-1,3-hexanediol to eliminate interferences. In: Communications in Soil Science and Plant Analysis Vol. 12, No. 7, p. 697-709 (1981); ISSN: 0010-3624, CODEN: CSOSA2.