Rosocyanine

Structural formula
General
Surname	Rosocyanine
Molecular formula	C 42 H 38 BClO 12 (chloride)
External identifiers / databases
CAS number 37204-72-1 PubChem 57473111 ChemSpider 21106498 Wikidata Q905712
properties
Molar mass	781.01 g mol −1
Physical state	firmly
safety instructions
GHS hazard labeling no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Rosocyanine is a dye that is formed from curcumin and borates .

use

The color reaction between borates and curcumin is used for the spectrophotometric detection of boron in food or various materials. The dye curcumin serves as a reaction partner for the boric acid . It occurs in some types of Curcuma, especially Curcuma longa Linn, the turmeric root . The highest concentration is in the rootstock, from which the substance is extracted. The reaction is very sensitive and detects even the smallest amounts of boron. The absorption maximum of rosocyanine is 540 nm, at which the colorimetric determination is also carried out.

Schlumberger coined the term rosocyanine to describe this red dye.

The formation of rosocyanine depends on the reaction conditions. The reaction is preferably carried out in a solution containing salt or sulfuric acid . The dye is also formed under other conditions, but in an alkaline solution it gradually decomposes. The reaction can be disturbed in the presence of silicates , fluoride , titanium , zirconium , molybdenum , beryllium and tungsten as well as at higher pH values . Oxidizing agents such as nitrates , bromates, etc. present in the solution must be removed before the determination, as they accelerate the decomposition of curcumin.

Rosocyanine is formed as a chelate compound in an acidic solution from curcumin and boric acid in a ratio of 2: 1. Curcumin has a 1,3- diketone structure and can therefore act as a chelating agent. Boric acid and its salts (borates) preferentially form chelates with 1,3-diketones. Such boron complexes are referred to as dioxaborines (here a 1,3,2-dioxaborine).

In rosocyanine, the two curcumin molecules are not in the same plane, but are twisted against each other. The same applies to the dye rubrocurcumin , which is formed when curcumin reacts with borates in the presence of oxalic acid .

In order to exclude the disturbing presence of other substances in the determination of boron according to the curcumin method, a variant was developed in which 2,2-dimethyl-1,3-hexanediol or 2-ethyl-1,3-hexanediol in addition to curcumin is largely neutral solution is added to the boron solution to be determined. A chelate complex is formed as an intermediate between the boron and the 1,3-hexanediol derivative, which is then extracted from the aqueous solution with an organic solvent. After acidification of the organic phase , rubrocyanine forms as a red dye, which is determined colorimetrically.

properties

As a solid, rosocyanine is a dark green powder with a metallic sheen; in solution it appears deep red. The dye is almost insoluble in water and in some organic solvents, it is poor in ethanol (0.01%), but significantly more soluble in pyridine , sulfuric acid and acetic acid (approx. 1%). An alcoholic red solution of rosocyanine turns temporarily deep blue when alkali is added.

literature

• L. Clarke, CL Jackson: Rosocyanins. In: American Chemical Journal Vol. 39, pp. 696-719 (1908); ISSN  0096-4085 , CODEN : ACJOAZ
• GS Spicer, JDH Strickland: Compounds of Curcumin and Boric Acid. Part I. The Structure of Rosocyanine. In: Journal of the Chemical Society (London), pp. 4644-4650 (1952); doi : 10.1039 / JR9520004644 .
• LJ Bellamy, GS Spicer, JDH Strickland: Compounds of Curcumin and Boric Acid. Part III. Infra-Red Studies of Rosocyanine and Allied Compounds. In: Journal of the Chemical Society (London), pp. 4653-4656 (1952); doi : 10.1039 / JR9520004653 .
• GS Spicer, JDH Strickland: Determination of microgram and submicrogram amounts of boron. I. Absorptiometric determination with curcumin. In: Analytica Chimica Acta Volume 18, pp. 231-239 (1958); ISSN  0003-2670 , CODEN: ACACAM.
• HJ Roth, B. Miller: On the knowledge of the color reaction between boric acid and curcumin, I. In: Archives of Pharmacy and Reports of the German Pharmaceutical Society Volume 297, Issue 10, pp. 617–623 (1964); ISSN  0376-0367 , CODEN: APBDAJ.
• HJ Roth, B. Miller: On the knowledge of the color reaction between boric acid and curcumin, II. In: Archives of Pharmacy and Reports of the German Pharmaceutical Society Volume 297, Edition 11, pp. 660-673 (1964); ISSN  0376-0367 , CODEN: APBDAJ
• Fritz Umland, Detlef Thierig, Gunther Müller: Photometric determination of boron in the picogram range. In: Fresenius' Zeitschrift für Analytische Chemie Volume 215, Issue 5, pp. 401-406 (1966); ISSN  0016-1152 , CODEN: ZACFAU.
• P. Quint, F. Umland: About the composition of the (1: 2) boron curcumin chelate »Rosocyanin«. In: Fresenius' Zeitschrift für Analytische Chemie Volume 295, Issue 4, pp. 269-270 (1979); ISSN  0016-1152 , CODEN: ZACFAU.
• David W. Dyrssen, Yu. P. Novikov, Leif R. Uppstrom: Chemistry of the determination of boron with curcumin. In: Analytica Chimica Acta Volume 60, Issue 1, pp. 139-151 (1972); ISSN  0003-2670 , CODEN: ACACAM.
• CG Kowalenko, LM Lavkulich: A modified curcumin method for boron analysis of soil extracts. In: Canadian Journal of Soil Science Vol 56, Issue 4, pp 537-539 (1976); ISSN  0008-4271 , CODEN: CJSSAR.
• Ulrike de la Chevallerie-Haaf, Axel Meyer, Günter Henze: Photometric determination of boron in ground and surface water. In: Fresenius' Zeitschrift für Analytische Chemie Volume 323, Issue 3, pp. 266-270 (1986); ISSN  0016-1152 , CODEN: ZACFAU.
• 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 Volume 28, Issue 11, pp. 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 Volume 12, Issue 7, pp. 697-709 (1981); ISSN  0010-3624 , CODEN: CSOSA2.

Individual evidence

1. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
2. ^ ME Schlumberger: Sur la réaction de l'acide borique sur la curcumine . Bulletin de la Société Chimique de Paris , NS Volume 5, pp. 194-202 (1866).