SYNTHESIS OF LOW-MOLECULAR-WEIGHT COPOLYMERS OF N-VINYLPYRROLIDONE
131
2
5
3
3
1
d
= 1.077 g cm . Found: R = 32.68 cm mol ;
Table 3. Hydrolysis of polymeric Oxacillin ester IIIa
at 37 C
4
calculated: R = 32.62.
The initiator, azobis(isobutyronitrile) (AIBN), was
recrystallized three times from chloroform ethanol,
Degree of hydrolysis, %
Time from start
of reaction, h
1
: 5. Yield of purified AIBN 76.2%, mp 103 C. Pub-
pH 7.3
pH 2.0
lished data: mp 103 C.
1
2
3
4
5
6
7
4
12
21
29
34
37
40
44
69
27
36
44
47
50
54
58
84
Dimethylformamide was purified by the standard
procedure [7]. Absolute 2-propanol, DCC (Fluka), and
Oxacillin sodium salt (iodometric activity 925 g mg )
1
were used without additional purification.
VP HEMA copolymer Ib. An 80-ml glass ampule
treated with live steam and dried was charged through
a funnel with 0.121 g of AIBN and then with a mix-
ture of 2 ml of VP, 0.58 ml of HEMA, 4 l of mer-
captoethanol, and 42 ml of 2-propanol. The ampule
was purged with argon, sealed, and placed in a ther-
mostat kept at 60 C. After heating for 24 h, the am-
pule was removed from the thermostat, cooled, and
opened. The viscous transparent polymerization prod-
uct was poured dropwise with stirring into a beaker
containing 300 ml of diethyl ether. The precipitated
copolymer was collected on a glass frit, washed with
fresh portions of ether, and dried in a vacuum without
heating to constant weight. Yield 1.71 g (63.2%).
Found: N 8.48%.
2
off, and the solution was poured into acetone to pre-
cipitate the reaction product (in so doing, unchanged
Oxacillin, which is readily soluble in acetone, re-
mained in the solution). After drying, 0.37 g (39.8%)
of the water-soluble polymeric Oxacillin ester was
obtained. The bound Oxacillin content was 31.7 wt %
according to UV data and 30.1 wt % according to
iodometric titration.
The UV spectra of aqueous solutions of Oxacillin
sodium salt, polymeric Oxacillin esters IIIa and IIIb,
and copolymer Ic were recorded on a Specord M-40
spectrophotometer. The IR spectra of copolymer Ic
and polymeric Oxacillin ester IIIa were measured on
a Bruker IFS spectrometer; samples were prepared as
films from chloroform solutions.
Synthesis of Oxacillin from its sodium salt.
Oxacillin sodium salt (2.5 g) was dissolved in 30 ml
of water. The solution was transferred into a 250-ml
separating funnel, and 50 ml of chloroform was added.
To the aqueous layer, 1 N HCl was added dropwise,
and the contents were shaken until the white precipi-
tate in the aqueous layer disappeared. After the pre-
cipitation in the aqueous layer was complete, the
acidification was stopped. The chloroform layer was
separated, washed with three 30-ml portions of water,
and dried over anhydrous sodium sulfate for 1 day at
room temperature. The chloroform layer was sepa-
rated, the solvent was removed on a rotary evaporator,
The molecular weights of copolymers Ia Ic were
determined by a sedimentation diffusion procedure
described elsewhere [2].
Hydrolysis of polymeric Oxacillin ester IIIa was
studied in glycine buffer (pH 2.0) and saline (pH 7.3)
at 37 C using the procedure described in [8].
The iodometric activity of Oxacillin and its poly-
meric esters was determined according to [6].
and the residue was dried in a vacuum. Yield 1.78 g
1
The antimicrobial activity of Oxacillin sodium salt
and polymeric Oxacillin ester IIIa was studied by the
method of tenfold serial dilutions in a liquid culture
medium (meat peptone broth, pH 7.0) [4]. The bac-
(
78.4%). Iodometric activity 920 g mg . Found:
S 7.84%; calculated: S 7.98%.
Polymeric Oxacillin ester IIIa. VP HEMA co-
polymer Ic (0.5 g) was dissolved in 5 ml of DMF, and
teria were grown for 18 h. The microbial load was
0.445 g of dry Oxacillin was added. The mixture was
5
5
10 microbial bodies per milliliter.
stirred at cooling with an ice salt mixture for 30 min,
and a solution of 0.3 g of DCC in 3 ml of DMF was
added. The solution was stirred for 2 h with cooling
CONCLUSIONS
(
0 5 C) and then for 5 h at room temperature. The
mixture was left overnight in a refrigerator, after
which the precipitate of dicyclohexylurea was filtered
(1) Conditions were found for preparing low-
molecular-weight water-soluble N-vinylpyrrolidone
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 1 2006