COMMUNICATIONS TO THE EDITOR
March 20, 1953
1.1 I I
TABLE I Sample
A
B
vap/c,c = 1.00% in 0.50NNaC1,3O0
0.328 0.358 16.17 16.74 N(Kjeldahl), 3 . 7 5 3.44 N(VanSlyke), % ' 1.02 0.25 Moles of -S03Na group per Total 1.68 1.80 on OH 0.95 0.87 on NHe 0.73 0.93 Activity, I.U./mg. 13 59
s, %
C
D
0.370 0.200 14.28 14.27 3.70 3.12 1.09 0.19 repeating unit 1.32 1.32 0.61 0.38 0.71 0.94 11 57
1.64 0.69 0.95 57
that, other conditions being equal, the contribution of sulfamic acid groups (above a certain limit) to the anticoagulant activity of polysaccharide polysulfate esters is far greater than that of sulfate ester groups. That there is no simple relationship, per se, between anticoagulant activity and acute toxicity is amply demonstrated by other of our sulfated chitosan products, shown in Table 11.
I I I 1
-Si-Si-0-Si-Si-0-Si-Si-
E
0.380 15.99 3.15 0.17
1513 I 1 I 1
+
The first member of this series, Si40Cllo,has been isolated and identified. Evidence also has been obtained for the existence of higher members, which, however, appear to undergo thermal decomposition during fractional distillation. This decomposition is probably the result of the thermal instability of long chains containing S i S i linkages and has prevented the isolation of higher members. Analyses and estimated molecular weights of higher boiling fractions, however, are in the expected region. One of these fractions appears to be a decomposition product of the second member of the series referred to above, by such a process as the following
I I I I
I I
-Si-Si-0-Si-Si-0-Si-Si-
I I
I I + I I I 1 I I -Si-Si-0-Si-Si-0-SiI 1 I I
I I
+ Si + C11
The hexachlorodisilane wab added to dry ether in a three-necked round-bottom flask fitted with a Activity, I.U./mg. 20 57 63 74 slip-seal stirrer. The solution was cooled to -78' L D ~ Oi.v. , in mice, mg. of kg. 3250 1500 1700 1250 in a solid carbon dioxide-trichloroethylene bath f 2 5 0 h500 h300 zt250 and, with constant stirring, a measured amount of water was added dropwise from a buret. The mixIn consideration of reports that the U.S.P. ture remained in the cold-bath for two hours and method does not give a reliable measure of i n vivo was then allowed to come to room temperature. activity with polysaccharide polysulfate synthetic The ether and unreacted hexachlorodisilane were anticoagulants,6.7J our products which have been removed by fractional distillation. The partial assayed by the U.S.P. method are currently being hydrolysis was then repeated with the recovered evaluated for activity by in vivo methods. hexachlorodisilane. In a series of six such reac(6) E. G. Snyder (to Wyeth Inc.), U.S. Patent 2,508,433, May 23, tions, a total of 230 g. of SizClswas partially hydro1950. lyzed. (7) C. N.Mangieri, R. Engelberg and L. 0. Randall, J . Pharmocol. The higher boiling residues remaining after the Erptl. Therap., 102, 156 (1951). (8) H.E. Stavely, P. J. Baker, Jr., and H. G. Payne, Federation removal of the ether and unreacted hexachlorodiProc., 11, 488 (1952). silane were combined and fractionated under reWARNER-CHILCOTT RESEARCH LABORATORIES JOHNDOCZI duced pressure. During the fractionation the conALEXFISCHMANtents of the distillation pot darkened gradually and 113 WEST1 8 STREET ~ ~ NEWYORK11, NEWYORK JOHNA. KING a considerable quantity of black residue remained RECEIVED JANUARY 29, 1953 after removal of all liquid material. All fractions were clear liquids, increasing in viscosity with inTHE PARTIAL HYDROLYSIS OF HEXACHLORODI- creasing temperature. While the first two fracSILANE tions exhibited relatively narrow boiling point Sir: ranges, no well defined holds were observed a t Part of the current research program of these lab- higher temperatures. oratories involves a comparative study of the parThe first fraction, b.p. 120-123' (13 mm.), tial hydrolysis, ammonolysis and thiohydrolysis of weighed about 12 g. Anal. Calcd. for SirOCllo: silicon halides. Using the method of Schumb and Si, 23.3; C1, 73.4; S i S i bonds, 2/mole; mol. Stevens, we have succeeded in partially hydrolyz- wt., 483. Found: Si, 23.2; C1, 73.4; S i S i iny hexachlorodisilane, obtaining the first member bonds, 1.96/mole; mol. wt., 475. The second of what is believed may be a new series of silicon fraction, b.p. 140-143' (14 mm.), weighed about oxychlorides. 5 g. Anal. Calcd. for Sir;OzCllz: Si, 23.5; C1, The partial hydrolysis of silicon tetrachloride 71.2; Si-Si bonds, 2/mole; mol. wt., 598. Found: produces an homologous series of oxychlorides of Si, 23.4, C1, 71.0, Si-Si bonds, 1.93/mole; mol. wt., the general formula Si,0,1Clzn+2. The analogous 595. The number of S i S i linkages was deterreaction with hexachlorodisilane would be expected mined by measuring the volume of hydrogen resimilarly to give a series of the type Si2,+20nC4,+e, sulting from decomposition of the sample with dias indicated by the schematic arrangement lute alkali while molecular weights were obtained from the freezing point depression of p-dioxane. I 1 Hz0 1 1 1. 1 -Si-$- -+ -Si-Si-0-Si-Si+ DEPARTMENT OF CHEMISTRY I 1 I 1 I 1 MASSACHUSETTS INST. OF TECH. W. C. SCHUMB TABLE I1
Sample
F
G
H
I
(1) W. C. Schumb and A. J. Stevens, THISJOURNAL, 72, 3178
(1950).
CAMBRIDGE, MASSACHUSETTS R. A. LEFEVER RECEIVED MARCH4, 1953
