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Title:
PREPARATION OF MONOISOCYANATE
Document Type and Number:
Japanese Patent JPH03115258
Kind Code:
A
Abstract:

PURPOSE: To obtain the subject compd. with a high vol./time yield while reducing by-products to a min., by separating a product obtd. by thermally cleaving a carbamic acid ester with a two-stage dephlegmator.

CONSTITUTION: A gaseous product principally composed of an isocyanate (R3-CNO) is obtd. by partially cleaving a compd. of formula I, (where R1 = an aliphatic, alicyclic, aromatic aliphatic or an aromatic hydrocarbon radical; R2 = an aliphatic group, alicyclic group, aromatic aliphatic group which gives alcohol (R2-OH) having a b.p. lower by at least 50°C than the isocyanate (R1-NCO), in reactor A, partially condensing an obtd. product by dephlegmator B, recycling a condensate contg. the uncleaved raw material to reactor A, partially condensing a gaseous material from the top by dephlegmator C, and urethane exchange-reaction of the condensate contg. the isocyanate (R1-NCO) with a compd. of formula II (where R3=R1, on the condition that (R3-NCO) has a b.p. lower by at least 50°C than (R1-NCO) in reactor E.


Inventors:
KURAUSU KEENITSUHI
PEETAA HAITOKENPAA
Application Number:
JP1990000232633
Publication Date:
May 16, 1991
Filing Date:
September 04, 1990
Export Citation:
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Assignee:
BAYER AG
International Classes:
B01J23/06; B01J27/08; B01J31/02; B01J31/04; B01J31/12; C07B61/00; C07C27/00; C07C29/00; C07C29/147; C07C31/02; C07C31/13; C07C33/18; C07C35/02; C07C37/00; C07C67/00; C07C241/00; C07C263/04; C07C263/12; C07C265/00; C07C265/04; C07C265/06; C07C265/10; C07C265/12; C07C271/06; (IPC1-7): B01J23/06; B01J27/08; B01J31/02; B01J31/04; B01J31/12; C07B61/00; C07C263/04; C07C265/04; C07C265/10; C07C265/12



 
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