Rosocyanine: Difference between revisions

| verifiedrevid = 448001794

| ImageFile = Rosocyanine.png

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| Section1 = {{Chembox Identifiers

| Section2 = {{Chembox Properties

| Formula = [B(C₂₁H₁₉O₆)₂]Cl (as chloride)

| MolarMass = 781.013 g/mol

| Appearance = dark-green colored solid

| Density =

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| Section3 = {{Chembox Hazards

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| Autoignition =

'''Rosocyanine''' and [[Rubrocurcumin]] are two red colored materials, which are formed by the reaction between [[curcumin]] and [[borate]]s.

The [[color reaction]] between [[borate]]s and [[curcumin]] is used within the [[spectrophotometrical]] determination and quantification of [[boron]] present in food or materials. [[Curcumin]] is a yellow coloring [[natural pigment]], found in the root stocks of some [[Curcuma]] species, especially in Curcuma longa (cf. [[turmeric]]) in concentrations up to 3 %. In the so called curcumin method for boron quantification it serves as reaction partner for [[boric acid]]. The reaction is very sensitive and so the smallest quantities of [[boron]] can be detected. The maximum absorbance at 540 nm for rosocyanine is used in this [[colorimetry|colorimetric]] method. The formation of rosocyanine depends on the reaction conditions. The reaction is carried out preferentially in acidic solutions containing hydrochloric or sulfuric acid. The color reaction also takes place under different conditions, but in [[alkaline]] solution however gradually decomposition is observed. The reaction might be disturbed at higher [[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-[[diketone]] structure and can therefore considered as a [[chelating agent]]. The formed boron complexes are called [[dioxaborines]] (here a 1,3,2-dioxaborine). Unlike the chelation of simple [[metal acetylacetonates]], however, the entire skeleton of curcumin is involved in [[resonance (chemistry)|resonance]] with the 1,3-dicarbonyl section, so the backbone is represented as an extended [[Conjugated system]]. Investigations on the structure show that the positive charge is distributed all over the molecule. In rosocyanine the two curcumin molecules are not coplanar, but rather, they are perpendicular relative to on another (as seen in the 3D model) as a result of the tetrahedral geometry of tetracoordinate boron. The same applies to rubrocurcumin for the same reasons.

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]].

Rosocyanine 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 [[ethanol]] it is very slightly soluble (up to 0.01%), but in [[pyridine]], [[sulfuric acid]] and [[acetic acid]] a clearly better solubility is observed (approx. 1%). An alcoholic solution of rosocyanine temporarily turns deeply blue on treatment with [[alkali]].

In rubrocurcumin one molecule curcumin is replaced with [[oxalic acid]]. Rubrocurcumin produces a similar red colored solution. Rosocyanine is an ionic compound, while rubrocurcumin is a neutral complex.

* 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.

* Spicer, G. S.; Strickland, J. D. H. Compounds of Curcumin and Boric acid. Part I. The structure of rosocyanin ''Journal of the Chemical Society (London),'' '''1952''', 4644-4650. ISSN: 0368-1769, CODEN: JCSOA9.

* L. J. Bellamy, G. S. 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. S. 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.

[[Category:Borate esters]]

[[de:Rosocyanin]]