From: Chapman, Robert D (ChapmanRD$##$navair.navy.mil)
Date: Thu Apr 20 2000 - 13:42:16 EDT
Dear Andrea:
My files have two good papers with reviews on that topic.
G. Kresze et al. Organic Prep. Proc. Int. 1987, 19, 329-426,
a 98-page review on gem-halonitroso compounds;
L. Anderson et al. J. Chem. Soc. Perkin Trans. 2 1992, 243.
Both give several references to C-13 NMR studies of that class and discuss
dimerization phenomena.
Robert D. Chapman, Ph.D.
Chemistry & Materials Division (Code 4T4200D)
Naval Air Warfare Center Weapons Division
China Lake, CA 93555 USA
> ----------
> From: Andrea Giordano
> Sent: April 20, 2000 9:42 AM
> To: Multiple recipients of list orglist
> Subject: ORGLIST: Dimerisation condition of nitroso comp. in
> synthesis
>
>
> Dear readers of orglist,
> I first apologise for the length of this mail, and i hope it may
> contribute
> to useful discussion among the interested people.
>
> 1. A well documented property of nitroso compounds is possible
> dimerisation
> of nitroso monomers via N=N bond. Recently, dimerisation of gem-chloro
> nitroso comp. has been reported, with ritention of chlorine atoms in the
> molecule ( I don't know the mechanism).
>
> 2. It is known that gem chloro-nitroso may be obtained via normal
> chlorination procedure (gaseous Cl2) over the corresponding oxime R=NOH.
>
> 3. Nitroso comp. are usually colored (blue) while dimers appear
> colourless;
> also gem chloro-nitroso cycloexane (from cycloexanone oxime and Cl2) has
> been described as a blue liquid. I don't know about an eventual
> chloro-nitroso dimer.
>
> Here is the matter: I am supposed to have in hand a gem chloronitroso
> which
> appears colourless. Being a substrate different from the usual ones
> (presence of C=O groups in the molecule) i don't know wheter this lack of
> colour is significant. To your knowledge, GS/MS and electrospray/MS
> analysis
> failed to reveal the presence of chlorine atom, probably because of
> deterioration of the sample in the first, and lack of protonation of the
> substrate in the second. In my hands i have only C13-NMR spectrum, where
> are
> evident the desappear of C=N signal of the starting oxime and a quaternary
>
> carbon signal at upper field, say 60 ppm, which is not too much intense
> respect to the others, considering that concentration of the sample is
> about
> 20mg/mL in CDCL3.
>
> My problem, of course, is the correct identification of my sample...can
> you
> help me?
> Do you also know in which conditions dimerisation of nitroso compounds is
> achieved in organic synthesis??
>
> Thank you very much!
> Andrea, CNR, Rome.
>
>
>
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