Crystal violet lactone

Carbonless Copy Paper. In carbonless copy paper, also referred to as pressure-sensitive record sheet, an acid-sensitive dye precursor, such as crystal violet lactone or /V-hen2oy11eucomethy1ene blue, is microencapsulated with a high boiling solvent or oil within a cross-linked gelatin (76,83,84) or in synthetic mononuclear microcapsules. Microcapsules that have a starch binder are coated onto the back of the top sheet. This is referred to as a coated-back (CB) sheet. The sheet intended to receive the image is treated on the front (coated-front (CF)) with an acid. When the top sheet is mechanically impacted, the dye capsules mpture and the dye solution is transferred to the receiving sheet where the acid developer activates the dye. 

Benzoyl leuco Methylene Blue (1), which is a phenothiazine leuco dye, has been known since 1900. The material was developed to extend the range of hues and colors obtainable in such applications as pressure-sensitive carbonless paper and to complement other classes of leuco dyes such as triarylmethanes, crystal violet lactone, and fluorans. Benzoyl leuco Basic Blue 3 (2), which is a phenoxazine leuco dye, is a more recent development. 

Considering the fact that 3,3-bis(4-dimethylaminophenyl)phthalide (1), commonly known as Malachite Green lactone, was reported1 well over 100 years ago, it is somewhat surprising to realize that the analogous 6-dimethylaminophthalide [Crystal Violet lactone (CVL)] (2) was not described until 1945,2 and that the vast majority of references cited herein are considerably more recent. 

The phthalide 25, obtainable by condensation of 4,4 -bisdimethyl-aminobenzophenone-2-carboxylic acid with 3-dimethylaminoacetanilide and subsequent hydrolysis, was diazotized in sulfuric acid and the resultant diazonium salt treated with copper powder to yield 26. However, better yields are reportedly obtained by carrying out ring closure of the diazonium salt in phosphoric acid.103 A further synthetic route has also been described in which phthalides undergo intramolecular cyclization in the presence of aluminum chloride and urea.104,105 Thus, Crystal Violet lactone (2) has been directly converted into phthalide 26.106... 

In 1954, the National Cash Register Company first marketed carbonless copying paper—NCR paper1—using Crystal Violet lactone (7)1 and benzoyl leuco Methylene Blue (8)2 as leuco dyes to make blue images. 

Scheme 10.2 Colour formation in the ring-opening of crystal violet lactone and related compounds...

Dyestuff soiution 1 g of crystal violet lactone [3,3-bis(p-dimethylaminophenyl)-6-dlmethylaminophthalide] is dissolved in 10 g of dibutyl phthalate by stirring at 90 °C for 15 min.The solution is brown/red. 

There are two main synthetic routes to Crystal Violet Lactone (CVL) and its analogues (Figure 1.23). The first involves the condensation of 4,4 -bismethyhydrol (1.73), also called Michler s Hydrol, with 3-dimethylaminobenzoic acid in dilute acid to give the leuco CVL, which is then oxidised to CVL. A wide variety of oxidants can be used but the preferred method uses hydrogen peroxide in basic solution. The oldest, and most versatile route starts by reacting 4-dimethylaminobenzaldehyde... 

Figure 1.22 Colour formation in Crystal Violet Lactone/developer system.

Crystal Violet lactone (132) can be regarded as a triarylmethane type in which the anion is retained in the molecule after exposure (Scheme 10). In this respect they also resemble the spiropyrans. 

Color formers are very sensitive to the addition of acids and solvents. In acid, crystal violet lactone (6) is only partially converted to the colored carboxylic acid (7) with opening of the lactone ring nax (log e) = 603 nm (4.41) in methanol / acetic acid (1/1)]. 

Condensation of Michler s hydrol (12) with 3-dimethylaminobenzoic acid (13) gives leuco crystal violet carboxylic acid (14), which is then oxidized to crystal violet lactone. 

MacLaren, D.C., White, M. A., 2003a. Dye — developer interactions in the crystal violet lactone-lauryl gallate binary system implication for thermochromism. Journal of Materials Chemistry 13, 1695-1700. 

Zhu, C.F., Wu, A.B., 2005. Studies on the synthesis and thennochromic properties of crystal violet lactone and its reversible thermochromic complexes. Thermochimica Acta 425, 7-12. 

Bis (4-(dimethylamino) phenyl-6-(dimethylamino) phthalide 3,3-Bis (p-(dimethylamino) phenyl-6-(dimethylamino) phthalide. See Crystal violet lactone... 

Crystalor CBN-020, Crystalor DC-6, Crystalor DC-7, Crystalor HBN-005, Crystalor HBN-010, Crystalor HBN-020. See Polymethylpentene Crystals of Venus. See Copper acetate (ic) Crystal violet. See Basic violet 3 Crystal violet lactone CAS 1552-42-7 EINECS/ELINCS 216-293-5 Synonyms 3,3-Bis (4-(dimethylamino) phenyl-6-(dimethylamino) phthalide 3,3-Bis (p-(dimethylamino) phenyl-6-(dimethylamino) phthalide 6-(Dimethylaino)-3,3-bis (4-(dimethylamino) phenyl)-1(3H)-isobenzofuranone 6-(Dimethylamino)-3,3-bis (p-(dimethylamino) phenyl) phthalide 1(3H)-Isobenzofuranone, 6-(dimethylamino)-3,3-bis (4-(dimethylamino) phenyl-Phthalide, 6-(dimethylamino)-3,3-bis (p-(dimethylamino) phenyl)-Empirical C26H29N3O2... 

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