dried in vacuo. The compound was recrystallised from ethanol.
Yield 39.99 g, 0.132 mol, 80%.
Found C 31.81, H 4.36. Calcd for C8H14O8S2: C 31.78, H
4.67%. Mp 144–146 1C; m/z 325.0 (M + Na)+; 1H-NMR
0
(500 MHz, CDCl3): d: 3.08 (s, 3H, SCH3), 3.13 (s, 3H, SCH3 ),
3.88 (dd, 1H, 2JH6,H6 = 10.1 Hz, JH6,H5 = 5.8 Hz, H-6), 4.01
(dd, 1H, JH6,H6 = 10.1 Hz, JH6 ,H5 = 6.1 Hz, H-60), 4.08
2
(dd, 1H, JH1,H1 = 11.2 Hz, JH1,H2 = 3.5 Hz, H-1), 4.23
3
0
2
3
0
0
3
0
2
(m, 1H, JH1,H1 = 11.2 Hz, H-10), 4.71 (m, 1H, H-3), 4.89
0
Fig. 7 SEM images of silica, templated on a 1 alcogel, with the
organics removed, 10 mm.
(m, 1H, H-4), 5.11 (m, 1H, H-2), 5.15 (m, 1H, H-5). 13C-NMR
(500 MHz, CDCl3): d: 38.67 (SCH3), 38.73 (SC0H3), 70.48 (C6),
73.49 (C1), 78.24 (C5), 80.56 (C4), 80.21 (C2), 85.92 (C3).
The NMR assignments were made from 2D spectra and
aided by comparison with published spectra.10
Other isohexide derivatives
endo-5-O-Methanesulfonyl-1,4:3,6-dianhydro-D-sorbitol and
2,5-di-O-propylsulfonyl-1,4:3,6-dianhydro-D-sorbitol
were
prepared using the above method by varying the ratio of
isohexide : sulfonyl chloride.
2,5-Di-O-p-toluenesulfonyl-1,4:3,6-dianhydro-D-sorbitol,
endo-5-O-p-toluenesulfonyl-1,4:3,6-dianhydro-D-sorbitol, 2,5-
di-O-p-toluenesulfonyl-1,4:3,6-dianhydro-D-mannitol and 2-O-
p-toluenesulfonyl-1,4:3,6-dianhydro-D-mannitol were prepared
by a published method;10 mono- and disubstituted isohexides
were prepared by varying the ratio of isohexide : sulfonyl
chloride.
Fig. 8 TEM of a single silica tube, 20 nm.
Hydrolysis and condensation continues until a uniform silica
skin is formed around the organogel, thus freezing in the
organogel structure. Scanning electron micrographs were
taken once the organogel template had been washed out
(Fig. 7). The image at lower magnification reveals that the
structure of the silica is highly elongated and one dimensional
ordering has been achieved. There is a large variation in the
length, width and shape, consistent with the variety observed
in the dried alcogel. The structure of a single tube was analysed
by transmission electron microscopy (TEM), the resultant
structure appears to be porous in nature (Fig. 8).
Gel tests
The required quantity of 1 (Table 1) was stirred into the
solvent in a glass vial. The vial was closed (apart from two
small holes in the cap) and placed in an oil bath at the
appropriate temperature; once a homogeneous solution was
obtained the vial was removed from the heat and the stirring
ceased. The phase behaviour was monitored as the solution
cooled.
Experimental
Sol–gel transcription of silica from a 1% w/v organogel
General
1 (0.0300 g, 0.099 mmol) was dissolved in benzylamine
(0.0319 g, 0.298 mmol), water (0.04 mL) and ethanol
(3 mL). The mixture was stirred and heated to 70 1C. After
2 h TEOS (0.16 g, 0.99 mmol) was added. After a further 1 h a
further aliquot of benzylamine (0.0400 g, 0.373 mmol) was
added. After 1 min the heater and stirrer were switched off and
the sample was left to cool slowly. On cooling a gel was formed
which was stable to inversion. The gel was left to age for over
a week.
Scanning electron micrographs were imaged on a Jeol 6400
SEM (samples were dried in air), transmission electron micro-
graphs (TEM) were imaged on a FIB200 TEM (samples dried
under vacuum). The NMR spectra were obtained using a
Bruker Advance DPX 300 spectrometer, with chemical shifts
reported on CDCl3 solutions relative to a standard reference
of tetramethylsilane.
Preparation of 2,5-di-O-methanesulfonyl-1,4:3,6-dianhydro-
D-sorbitol (1)
Conclusions
Isosorbide (24.10 g, 0.165 mol, Lancaster) was slowly added to
pyridine (120 mL) cooled in an ice–salt water bath.
When completely dissolved, methanesulfonyl chloride
(31 mL, 0.40 mol) was added dropwise over 30 min. On the
addition of the methanesulfonyl chloride, the colourless
mixture turned through dark yellow to brown. The solution
was stirred at room temperature (B15 1C) for 20 h. The
resulting slush was heated to 55 1C and water (250 mL) was
added. A white solid precipitated. The mixture was heated to
reflux for 2 h and once cooled the white solid collected and
1 gels a range of alcoholic and aromatic solvents as well as
water. The structure in the solid state analysed by single
crystal X-ray crystallography did not contain any strong
hydrogen bonds. The nano- and microstructures observed by
electron microscopy form as a result of the roof-like structure
of 1 which encourages molecular stacking reinforced by
intramolecular interactions. Due to the absence of long alkyl
chains to increase van der Waals forces and aromatics to
encourage p–p interactions the gelation is finely balanced and
ꢀc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009
482 | New J. Chem., 2009, 33, 479–483