1788
Cihelník, Stibor, Lhoták:
6.90–6.94 d, 1 H (arom . H); 7.52–7.56 t, 1 H (arom . H); 7.64–7.68 t, 1 H (arom . H); 7.98– 8.02 d,
1 H (arom . H).
2-(9-Hydroxy-5-oxo-5H-diben zo[a,j]xan th en -14-yl)ben zen e-1-sulfon ic Acid
(Naph th osulfon efluorescein , 12)
Method B (MW O). Th e dye was prepared in 23% yield from n aph th oresorcin ol (n aph -
th alen e-1,3-diol) an d 2-sulfoben zoic an h ydride an alogously to sulfon efluorescein (9). Naph -
th osulfon efluorescein could n ot be an alysed by com bustion due to sublim ation at h igh
tem peratures. 1H NMR (D2O–K2CO3): 6.44–6.46 s, 2 H (arom . H); 6.48–6.52 d, 2 H (arom . H);
6.72–6.7 t, 2 H (arom . H); 6.84–6.88 d, 2 H (arom . H); 6.90–6.94 d, 1 H (arom . H); 6.98–7.02 d,
2 H (arom . H); 7.06–7.12 t, 2 H (arom . H); 7.20–7.24 d, 2 H (arom . H); 7.52–7.56 t, 1 H
(arom . H); 7.62–7.68 t, 1 H (arom . H); 7.98–8.02 d, 1 H (arom . H).
2-(2,7-Dih ydroxy-9H-xan th en -9-ylium -9-yl)ben zen e-1-sulfon ate
(Hydroquin on esulfon efluorescein , 13)
Method B (MWO). Th e dye was prepared in 56% yield from h ydroquin on e an d 2-sulfo-
ben zoic an h ydride usin g th e procedure described for sulfon efluorescein (9). Th e h ydro-
quin on esulfon efluorescein could n ot be an alysed by com bustion due to sublim ation at h igh
tem peratures. 1H NMR (D2O–K2CO3): 6.42–6.44 s, 2 H (arom . H); 6.48–6.52 d, 2 H (arom . H);
6.82–6.86 d, 2 H (arom . H); 6.90–6.94 d, 1 H (arom . H); 7.52–7.56 t, 1 H (arom . H); 7.62–
7.56 t, 1 H (arom . H); 7.98–8.02 d, 1 H (arom . H).
2-(6-Hydroxy-3-oxo-3H-xan th en -9-yl)ben zoic Acid (Fluorescein , 14)
Method B (MWO). Fluorescein was syn th esised from resorcin ol an d ph th alic an h ydride
usin g gen eral m eth od B, irradiation 30 s, with addition of few drops of 85% H3PO4. Th e
yield was 97% (optim ised, based on an h ydride). Th e product was iden tical with com m ercial
stan dard (Lach em a Brn o, Czech Republic).
2-(6-Hydroxy-4,5-dim eth yl-3-oxo-3H-xan th en -9-yl)ben zoic Acid
(4,5-Dim eth ylfluorescein , 15)
Method B (MWO). From 2-m eth ylresorcin ol (248 m g, 2 m m ol), ph th alic an h ydride (148 m g,
1 m m ol) an d on e drop of 85% H3PO4 (MWO, 350 W, 30 s), com poun d 15 (230 m g, 68%)
was isolated usin g repeated precipitation from aqueous am m on ia. For C22H16O5 (360.4)
calculated: 73.33% C, 4.48% H, 22.20% O; foun d: 72.98% C, 4.60% H, 22.52% O. 1H NMR
(D2O–K2CO3): 1.92–2.00 s, 6 H (-CH3); 6.56–6.62 d, 2 H (arom . H); 6.68–6.74 d, 2 H (arom . H);
7.22–7.28 d, 1 H (arom . H); 7.48–7.62 m , 2 H (arom . H); 7.70–7.76 d, 1 H (arom . H).
2-(6-Hydroxy-3-oxo-3H-xan th en -9-yl)-4(5)-n itroben zoic Acid; A Mixture of Isom ers
(4′(5′)-Nitrofluorescein , 16)
Method B (MWO). Th e dye was prepared in 82% yield from 4-n itroph th alic an h ydride an d
resorcin ol with a catalytic am oun t of H3PO4 an alogously to th e 4,5-dim eth ylfluorescein (15)
procedure. For C20H11NO7 (377.3) calculated: 63.67% C, 2.94% H, 3.71% N; foun d: 63.41% C,
2.98% H, 3.63% N. 1H NMR (D2O–K2CO3): 6.48–6.54 s, 2 H (arom . H); 6.56–6.62 d, 2 H
Collect. Czech. Chem. Commun. (Vol. 67) (2002)