‘Naturalization’ of textile disperse dyes through glycoconjugation: the case of a bis(2-hydroxyethyl) group containing azo dye Roberto Bianchini, a, * Giorgio Catelani, b, * Riccardo Cecconi, c Felicia D’Andrea, b Elena Frino, b Jalal Isaad a and Massimo Rolla a a Dipartimento di Chimica Organica ‘U. Shiff’, Universita ` di Firenze, Via della Lastruccia 13, I-50019 Sesto Fiorentino (FI), Italy b Dipartimento di Chimica Bioorganica e Biofarmacia, Universita ` di Pisa, Via Bonanno 33, I-56126, Pisa, Italy c Lanartex snc Laboratory, Via 1 Maggio, Montemurlo (PO), I-59013, Italy Received 27 November 2007; received in revised form 7 February 2008; accepted 8 February 2008 Available online 15 February 2008 Presented at Eurocarb 14th Lu ¨ beck, Germany, September 2007 Abstract—A family of five strictly related glycoconjugated azo dyes (GADs), characterized by the presence of the same chromo- phore and a variable number (1–4) of deprotected hexose units, has been prepared by employing succinate bridges for connecting the azo dye and the sugar portions. The modulation of the hydrophilic portion determines the appreciable changes in the water solubility of GADs. In all the cases, however, hydrophobic fibres (polyester) were homogeneously dyed with GADs at temperatures lower than that used for original azo dyes, at atmospheric pressure, and avoiding the use of surfactants. Furthermore, GADs show an interesting multipurpose character leading to dyeing well also the natural fibres as, for instance, wool. The presence of a variable number of hexose units in the different GADs determines some changes in the colour intensity of dyed fabrics, but in all the cases an appreciable rubbing and water fastness were maintained. Ó 2008 Elsevier Ltd. All rights reserved. Keywords: Azodyes; D-Galactose; Lactose; Succinates; Glycoconjugation; Textile dyeing 1. Introduction Archaeological traces of dyed clothes have been found through the world, showing that ancient civilizations in America, in the Mediterranean area and in the Cen- tral Asia developed efficient dyeing techniques using natural dyestuffs prevalently obtained from plants, but also from insects and shellfish. 1 Until the second half of the 19th century, textile industry developed more and more sophisticated techniques obtaining an impres- sive level of quality in dyeing fabrics with natural dye- stuff. 1 Many vegetable natural colours are constituted by different classes of chromophores O- or C-glycosyl- ated with mono-, di- or oligosaccharide moieties. Exam- ples are 1 the cartamine, a deep red glycoside from Safflower (Cartamus tinctorius), the blue indicotine from Woad (Isatis tinctoria), obtained by the hydrolysis of the colourless glycoside indacane, the ruberitric acid from Madder (Rubia tinctorum), a glycoside of shining red colour constituted from alizarine and the disaccharide primaverose. Starting from the second half of the 19th century, following the Industrial Revolution, natural dyes have been almost completely replaced by synthetic compounds, which are less expensive and much easily available. Nowadays, textile industries dispose off a huge number (about 10,000) of synthetic dyes, 2 pro- duced by chemical industries throughout the world in an estimated overall production of 700,000 tons/year. 2 Amongst the different classes of synthetic dyes cur- rently used in the textile industry, the by far most com- mon is constituted by the so-called ‘disperse dyes’, represented mainly by the azo and the anthraquinone 0008-6215/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.carres.2008.02.009 * Corresponding authors. Tel.: +39 0502219700; fax: +39 0502219660 (G.C.); tel.: +39 0554573486; fax: +39 0554573531 (R.B.); e-mail addresses: roberto.bianchini@unifi.it; giocate@farm.unipi.it Available online at www.sciencedirect.com Carbohydrate Research 343 (2008) 2067–2074