Title: Lacmoid
Additional Names: Resorcin blue; Iris Blue B; Fluorescent Blue; C.I. 51400
Literature References: Prepn: Traub, Hock, Ber. 17, 2615 (1884); Musso et al., Angew. Chem. 73, 434 (1961). Discussion of structure controversy: H. J. Conn's Biological Stains, R. D. Lillie, Ed. (Williams & Wilkins, Baltimore, 8th ed., 1969) pp 283-284. See also: Colour Index vol. 4 (3rd ed., 1971) p 4468.
Properties: Dark-violet, lustrous scales or granules. Freely sol in methanol, ethanol, amyl alcohol, glacial acetic acid, acetone, phenol. Sparingly sol in water, ether. Practically insol in chloroform, benzene, petr ether.
Use: As acid-base indicator in 0.2% soln in alcohol. pH: 4.4 red; 6.4 blue. Satisfactory for titrating mineral acids, strong bases, many alkaloids; determining alkalinity and temporary hardness in water analysis. Biological stain; dye for wool, silk. Not adapted for carbonates, weak inorganic and organic acids, weak bases. Lacmoid is more sensitive than litmus, particularly in form of test paper. |