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Investigation of the Self-Diffusion of Small Molecules in a High-Molecular Environment.

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1-Butylfluorocyclopropanes are obtained analogously when
n-butyllithium is used as metalating agent (e.g. 6 % syn- and
anti-7-butyl-7-fluoronorcarane
from cyclohexane). With phenyllithium, only tetraphenylethylene was formed - presumably
via a,a'-difluorostilbene. If, however, the stationary concentration of the organometallic compound is diminished by ate-complex formation with pentaphenylantim~nyl~],
approximately
1Yo difluoronorcarane can be detected.
General procedure:
A solution of organolithium compound (0.20 mole) in petroleum ether or diethyl ether is added dropwise over a period
of 15 minutes to a mixture of dichlorofluoromethane (or chlorodifluoromethane) (40 ml) and olefin which is kept at -40 to
-50°C. The reaction mixture is then allowed to warm to room
temperature and the excess of halogenomethane allowed to
evaporate. The mixture is hydrolyzed with dilute acid, washed,
and dried. After evaporation of the lowest boiling constituents
the mixture is fractionated, if necessary under vacuum, with a
spinning band column. The reaction products usually have to be
purified by gas chromatography.
Received: December 21,1970 [Z 324 IE]
German version: Angew. Chem. X3. 150 (1970)
[*] Priv.-Doz. Dr. M. Schlosser and Dr. Le Van Chau
Organisch-chemisches Institut der Universitat
69 Heidelberg, Im Neuenheimer Feld (Germany)
and Institut fur experimentelle Krebsforschung
am Deutschen Krebsforschungs-Zentrum,
69 Heidelberg (Germany)
I"*] Financiai support by the Deutsche Forschungsgemeinschaft and
gifts of chemicals by Farbwerke Hoechst are gratefully acknowledged.
[ l ] Cf. U. Burgerand R. Huisgen, Tetrahedron Lett. 1970,3049,3053,
3057; L. Friedman, R. J. Honour, and J. G. Berger, J . Amer. Chem. SOC.
92, 4640 (1970); M. Schlosser and G. Heinz, Chem. Ber. 103, 3543
(1970), and further literature cited there.
[2] Nucleophilic replacement of halogen in carbenes or carbenoids by
organolithium compounds: C. L. Cfoss and L. E. Closs,J. Amer. Chem.
SOC.83, 1003 (1961); 8-5, 99 (1963); 0. M. Nefedov, V.I. Shiryaev,
and A. S. Khachaturov, Zh. Obshch. Khim. 35,509 (1965); Chem. Abstr.
63, 517e (1965); 0.M. Nefedov, V. 1.Shiryaev, and A. D. Petrov, Zh.
Obshch. Khim. 32, 662 (1962); Chem. Abstr. 57, 149718 (1962);
W. L. Dilling, J. Org. Chem. 29, 960 (1964); G. Khbrich, Angew.
Chem. 79, 15 (1967); Angew. Chem. internat. Edit. 6, 41 (1967), 47f.
[3] G. Wirtig and K. Clauss, Liebigs Ann. Chem. 577, 26 (1952); G.
Wjftig and E. Benz, Tetrahedron 10,37 (1960).
C O N FE R E N C E REP 0 RTS
Investigation of the Self-Diffusion of SmaiI Molecules in a High-Molecular Environment
By Robert Kosfeld[*I
Self-diffusion is a translatory motion in which the molecules
move in any direction with respect to their immediate environment in accord with statistical laws. This molecular-kinetic process depends on the intermolecular interactions between the
molecules that determine the structure of the relevant system.
The characteristic parameter of self-diffusion is the self-diffusion coefficient (SDC). Accurate knowledge of this coefficient
as a function of the temperature, pressure, particle concentration of individual components, and the duration of measurement affords an insight into the structure of the system under
investigation.
Particular interest attaches to the study of the translational
motion of small molecules in a polymeric environment since
both synthetic and biological polymers often contain components of low molecular weight (for example as plasticizers).
Not only will the polymeric part of the system exert an effect
on the mobility of the solvent molecules but the solvent molecules in turn will have a profound influence on the properties
of the polymeric part of the system.
The spin-echo technique is well suited for the study of molecular-kinetic pmcesses, and offers several distinct advantages
over conventional methods for the determination of the SDC.
Thus the molecules or even parts of molecules are labeled in
that the relevant atoms acquire a certain phase difference with
respect to one another. Compared with the tracer technique
the system is far less perturbed; consequently the results obtained represent a better approximation to the processes occurring in the unperturbed system.
In multicomponent systems in which several self-diffusion processes are taking place the individual events can be detected
simultaneously and independently of one another.
Whereas the usual spin-echo technique for determination of
the SDC employs field gradients of the same sign that are either
constant with respect to time or, as in the method devised by
Tanner and Sfejskall'], applied as pulses, we have developed
Angew. Chem. internat. Edit. / Vol. 10 (1971) / N o . 2
a method utilizing alternating field gradient pulses121.This technique permits determination of the SDC in the wide,range
between lo-"' and
cm*s-'. The shortest diffusion time
measured so far with our apparatus is 80 p.The minimum time
that can be measured using field pulses of the same sign is about
2000 ps. The method has been used for diffusion-time dependent SDC measureliients on the sintered glass membrane/
benzene system and the effect of hindered diffusion has been
studied more closely.
More attention was devoted to the study of the temperature
dependence of the SDC of polystyrene (PST) in a solution containing 85.7 mole-% of deuterated benzene. Between 40 and
100°C the diffusion process can be described by an Arrhenius
equation with an activation energy of A E = 3.7 kcal mole-'.
In the case of pure benzene the activation energy for the diffusion process was found to be A E = 3.0 kcal mole-'.
The temperature and concentration dependence of the SDC
of benzene in crosslinked and non-crosslinked PST was the subject of a detailed investigation. An Arrhenius plot also gave
a linear relationship for the SDC of benzene in both crosslinked
and . non-crosslinked PST. The activation energy increases
with the polymer concentration from 3 kcal mole-' to 12 kcal
mole-' in a system containing 25 wt.-% of benzene. The concentration dependence of the SDC of benzene above 60 wt.-%
of benzene is described adequately by a simple exponential
relation. Evaluation of the numerical results according to the
Dooiittle-Fujita theoryl31 permits determination of the relative
free effective volume f and the SDC D,, of pure PST:
T ("C)
30
50
5.9
40
61
9.5
D,, (cm's-')
60
70
79
7.9
2.2 x lo-" 4 . 6 ~ 1 0 - ' I 9.0x10-@ l.8x10-9 1 . 6 ~ 1 0 - ~
T("C)
80
90
100
/ x 100
8.6
9.6
10.1
7.3x10-*
f x 100
D,, (em's-')
4 . 6 ~ 1 0 - ~2 X 1 0 - @
Other authors[4]have obtained a value of 0.13 for the free volume from pressure- and temperature dependent volume meas-
139
urements at 90°C. In this case the free volume is regarded
as the total volume less the volume of the molecules in closest
packing. It should however be noted that an additional volume
is taken up by intermolecular interactions between molecules
of polymer and of benzene which is no longer available to the
benzene molecules in the self-diffusion experiments. This would
offer at least a qualitative explanation of the difference in the
free volumes determined by the two methods.
In conclusion, attention is drawn to the fact that a “discontinuity” is observed at 50°C in the plot of the temperature
dependence of the SDC of pure PST which can be attributed
to rearrangement of the phenyl rings.
Lecrure at Bochum on November 26, 1970 [VB 265 IE]
German version Angew Chemie 83, 151 (1971)
[‘I
Doz. Dr. R. Kosfeld
Institut fur Physikalische Chemie der Technischen Hochschule
5 1 Aachen, Ternplergraben 59 (Germany)
[ I ] J. E. Tanner and E. 0.Stejskal, J . Chem. Phys. 42, 288 (1965).
[2] I?. Gross and R. Kosfefd,Messtechnik 7/8,171 (1969).
[3] A. K. Doolirtie and H.Fujifa, Advan. Polymer Sci. 3, 1 (1961).
[4] R. N. Haward, H. Breuer, and G. Rehage, Polymer Lett. 4,375
(1966).
Synthesis, Chemistry, and Biological Properties of
Some Novel Hormonal Fluorosteroids
By G . A . Boswetl, Jr. (Lecturer), A . L . Johnson, and J.P.
McDevitt “1
Previous investigations into the effect of 6,6-difluoro substitution of steroids on their hormonal activity showed that in certain progestational steroids activity was considerably enhanced“]. It was of interest to estabtish if such a modification
would increase the biological activity of the clinically important
17a-ethynyl-19-nortestosterone(norethindrone). Introduction
of the two fluorine atoms onto C-6 of the 19-norsteroid nucleus
was accomplished using nitrosyl fluoride and sulfur tetrafluoride
as the key reagents (Schemes I and 2).
Treatment of 3fi,17P-diacetoxy-5(6)-estrene (2) with NOF in
CH2CI, gave a separable mixture of 3P, 17j3-diacetoxy-Sa-fluoro-6-nitroiminoestrane (1 7 and the dimer of the 5a-fluoro6P-nitroso derivative (18)12. The latter on standing reverted
to the monomer, and tautomerized to the 5a-fluoro-6-oxirne
(19), which was deaminated with nitrous acid to give the 5a-
i’
OAc
1. A q O , AcC1, CsHsN
2. NaBH,/THF/CH,OH
1. NOF
2. A1201
3. A c 2 0 , C5H5N
Ac
Ac
(2)
SF,, H F
1
QAc
AcO
0
F
(4)
NaRlI,/C2H5OH
Dioxane
OH
Scheme 1. Synthesis of 17a-ethynyl-6,6-difluoro-19-nortestosterone
(13) and derivatives from 19-nortestosterone (1).
140
Angew. Chem. internat. Edit. / Vot. 10 (1971) / N o . 2
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