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Free-Radical Initiated Addition of Bromotrichloromethane to Allyl Isocyanate.

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unsaturated intermediate (5) reacts with the diphosphine in
a second, rapid step, giving an intermediate (4) which forms
the chelate with loss of CO.
Received: May 12th, 1966
[Z 230 IE]
German version: Angew. Chem. 78, 646 (1966)
~~
.
A solution of ally1 isocyanate (20 g) and AIBN (1
bromotrichloromethane (200 g) is refluxed for 3 hr
steam bath. Evaporation of the excess of BrCCI3 gives
product ( l ) , which is distilled at 92-94OCi0.5 mm.
80 %, colorless oil, n2,a = 1.5269.
g) irr
on a
crude
Yield
--
[ I ] I<inetic Studies of Substitution Reactions of Metal Complcxcs, Part 4. - Part 3 : H . Werner and R. Prinz, Chem. Ber., in
press.
CHz-=CH--CH?-NCO + BrCCIS
->
[2] J . Chat? and H . R . Watson, J . chem. SOC.(London) 1961,
4980; F. Zingules and F. Canziuni, Gazz. chim. ital. 92, 343
( I 962).
[ 3 ] H . Werner and R. Prim, Angew. Chem. 77, 1041 (1965);
Angew. Chem. internat. Edit. 4 , 994 (1965); H . Werner, J. organomet. Chemistry 5 , 100 (1966).
Free-Radical Initiated Addition of
Bromotrichloromethane to Ally1 Isocyanate
By Dr. W. J. Farrissey, Jr., F. P. Recchia, and
Dr. A. A. R. Sayigh
The Upjohn Company. Carwin Research Laboratories,
North Haven, Connecticut (U.S.A.)
The addition of radical species to ally1 isocyanate has
previously not been examined. We have now found that
bromotrichloromethane undergoes rapid addition to the
C = C double bond in the presence of azobisisobutyronitrile
(AIBN) to form 2-bromo-4,4,4-trichlorobutyl isocyanate ( I ) .
CI3C-CH2-CHBr-CH:
NCO
i 1)
The N M R spectrum[ll of (1) comprises two doublets at
3.38 and 3.83 ppm (2 CH2 groups) and a 5-peak multiplet
at 4.45 ppm (CH group).
With methanol, ( I ) gives the urethane, m.p. 64-65.5"C;
with p-toluenesulfonamide in refluxing toluene it gives the
urea derivative, m.p. 185-186 'C.
With stoichiometric quantities (or less) of BrCC13 in the
synthesis of ( 1 ) the yield decreases and the amount of less
volatile material increases. Presumably telomerization occurs,
since the isocyanate function remains intact.
With CC14 in the presence of AIBN or benzoyl peroxide,
ally1 isocyanate reacts primarily at the isocyanate group.
Received: April 26th, I966
[Z 229 IEI
German version: Angew. Chem. 75, 616 (1966)
[ I ] Varian A-60 spectrometer; chloroform solution with tetramethylsilane as internal standard.
CONFERENCE REPORTS
Macromolecular Colloquium
This colloquium was held on March 3rd-5th, 1966, at the
Institut fur Makromolekulare Chemie der Universitlt Freiburg (Germany).
Studies of the Thermal Dehydrochlorination of
Poly(viny1 chloride)
D . Brriiin and M . Thallmaier, Darmstadt (Germany)
I n spite of numerous studies of the thermal removal of
hydrogen chloride from poly(viny1 chloride) (PVC), the
positions in the macromolecule responsible for initiation of
this reaction have hitherto remained obscure. To test the
effect of irregularities in structure of the PVC chains on
thermal decomposition, we have investigated the dehydrohalogenation of copolymers of vinyl chloride with small
amounts of diethyl fumarate (DEF), isobutene (IBu), vinyl
bromide (VBr), and 2-chloropropene (2-CP). The rate of
thermal dehydrohalogenation of the copolymers with VBr
and 2-CP between about 100 and 140 "Cis proportional to the
square of the mole fraction of these units in the copolymers;
it can thence be shown that the rate is proportional to the
mole fraction of those VBr or 2-CP units which are present
in sequences of two or more units. It follows that under the
experimental conditions used the liberation of a molecule of
hydrogen halide from an isolated, thermally labile structural
unit does not initiate further loss by a "zip" mechanism.
Longer polyene sequences arise only if loss of a second
molecule of hydrogen halide is possible owing to the neighboring presence of a second labile unit, or o n use of higher
temperatures. The significance of these results for the
mechanism of thermal removal of HCl from poly(viny1
chloride) and for the mode of action of heat stabilizers was
discussed.
Aiigew. Chem. internat. Edit.
/
Vol. 5 (1966) 1 No. 6
The polyene sequences arising on thermal decomposition can
be analysed by means of their electronic spectra. The regularities in polyene spectra permit approximate establishment of the distribution of polyene sequence lengths in PVC
and poly(viny1 bromide) (PVBr), and in vinyl chloride-DEF
and -1Bu copolymers. In degraded PVC, the frequency of
occurrence of sequences decreases continously with increasing
number of conjugated double bonds; in degraded PVBr,
oolvene seauences with a mean of 12 to 13 double bonds are
-~
commonest. For PVC, the ratio of the total number of
polyene sequences to the amount of HCI liberated decreases
with increasing time of degradation, i.e. with increasing
removal of HCI; the frequency distribution is shifted in
favor of shorter sequences, a result attributed to preferential
disappearance of the longer polyene sequences by secondary
reactions.
Solution Properties of Polyvinylpyrrolidone
W . Burchard, Freiburg (Germany)
Light-scattering measurements on polyvinylpyrrolidone(PVP)
in several solvents and in mixtures of solvent and precipitant show that the radius of gyration is clearly dependent
on the composition of the @-solvent (change of conformation). The change of one conformation into another is,
however, initiated far above the O-point by a relatively
small amount of precipitant. The conformational change is
particularly marked for aqueous solutions to which acetone
or dioxane has been added. Acetone causes expansion of the
coil, dioxane a contraction; ihese effects are not due to
intermolecular interactions. The conformational change is
cxplained as being due to preferential solvation of certain
groups in the macromolecule.
607
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ally, bromotrichloromethane, free, isocyanates, additional, radical, initiate
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