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Popelka, Rypáček:
2-[(2,4-Din itroph en yl)sulfan yl]eth an -1-ol (3)
Adoptin g th e procedure described in literature9, a solution of 2-sulfan yleth an -1-ol (30 m m ol,
2.1 m l) in 30 m l of CHCl3 was slowly added in to a m ixture of 1-fluoro-2,4-din itroben zen e
(5.6 g, 30 m m ol) an d TEA (7 m l). Th e brown ish reaction m ixture was stirred at room tem -
perature overn igh t. Th e reaction m ixture was diluted with CHCl3 (200 m l), extracted with 1 M
HCl (1 × 20 m l) an d water (2 × 20 m l). Th e ch loroform ph ase was separated, dried over an -
h ydrous MgSO4 an d filtered. Th e yellow product was twice recrystallized from CHCl3. Yield
4.5 g (61%); m .p.: 99.5–101 °C. For C8H8N2O5S (244.2) calculated: 39.34% C, 3.30% H,
11.47% N, 13.13% S; foun d: 39.40% C, 3.20% H, 11.30% N, 13.06% S. 1H NMR (CDCl3):
8.95 s, 1 H, J(3,5) = 2.5 (H-3), H-arom .; 8.28 dd, 1 H, J(3,5) = 2.5, J(5,6) = 9.0 (H-5), H-arom .;
7.62 d, 1 H, J(5,6) = 9.0 (H-6), H-arom .; 3.97 t, 2 H, J = 5.9, SCH2CH2OH; 3.24 t, 2 H, J =
5.9, SCH2CH2OH.
2-(Tritylsulfan yl)eth an -1-ol (4)
A procedure described in literature was followed13. Trityl ch loride (4 g, 14 m m ol) was dis-
solved in 60 m l of petroleum eth er an d 1 m l (14 m m ol) of 2-sulfan yleth an -1-ol was added.
Th e m ixture was refluxed for 15 m in . Wh ite crystals th at precipitated in reaction m ixture
were collected by filtration an d th e product was crystallized from eth an ol. Fin al
recrystallization was from a m ixture of toluen e an d petroleum eth er (1:1 v/v). Yield 3.2 g
(71%); m .p.: 115–116 °C. For C21H20OS (320.5) calculated: 78.71% C, 6.29% H, 10.01% S;
foun d: 78.6% C, 6.3% H, 9.9% S. 1H NMR (CDCl3): 7.14–7.38 m , 15 H, H-arom .; 3.31 t, 2 H,
J = 6.0, SCH2CH2OH; 2.41 t, 2 H, J = 6.0, SCH2CH2OH.
Polym ers
Polym ers were prepared by rin g-open in g polym erization of L-lactide in dioxan e in itiated
with tin (II) 2-eth ylh exan oate an d co-in itiated with on e of th e four differen t co-in itiators
possessin g OH groups (Sch em e 2). Th e m on om er-to-Sn (Oct)2 m olar ratio was 50:1 except th e
case of polym erization with co-in itiator 1 wh en th e 15:1 ratio was used. Th e m on om er-to-
co-in itiator ratio was varied as sh own in Table I. Th e polym erization was carried out un der
n itrogen atm osph ere in sealed am poules at 60 °C for 40 h . Th e reaction m ixture was fin ally
poured in to m eth an ol an d th e precipitated polym er was isolated by filtration or cen tri-
fugation .
Modification of En d Groups
Isolated polym er precursors 1a–4a were subjected to th e followin g treatm en t, wh ich con -
verted th e in itiator en d groups in to th iol groups.
To regen erate th iol en d groups from precursor 1a, an excess of low-m olecular-weigh t th iol
was used. An am oun t of 1.5 g of polym er 1a was dissolved in dich lorom eth an e (16 m l) an d
4 m l of 2-sulfan yleth an -1-ol was dropwise added to th e solution . Upon stirrin g for 30 m in ,
dark-red precipitation of low-m olecular-weigh t tin (II) th iolate was form ed. It was rem oved
by filtration an d th e polym er solution was precipitated in to m eth an ol.
Allyl en d groups of th e polym er 2a were m odified by radical addition of triph en yl-
silan eth iol to th e double bon d usin g th e procedure described for low-m olecular-weigh t
alken es14. Polym er 2a, correspon din g to 146 µm ol of ch ain en ds, triph en ylsilan eth iol (121 m g,
Collect. Czech. Chem. Commun. (Vol. 68) (2003)