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Description  |
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FIELD OF THE INVENTION
This invention relates to compositions of cyanuric chloride to reduce
dusting and lumping and to provide flowability of solid cyanuric chloride
and more particularly it relates to cyanuric chloride composition
compatible for further synthesis to herbicides and optical brighteners.
BACKGROUND OF THE INVENTION
Cyanuric Chloride, symmetrical 2,4,6-trichloro-1,3,5-triazine, is a useful
intermediate. However current handling methods result in significant
amounts of fumes and dust which present a health hazard to plant
personnel.
In addition cyanuric chloride on storage has been noted for its tendency to
cake, lump and bridge in its storage containers. The latter proclivity
presents serious hazards as removal of such caked cyanuric chloride from
storage containers requires special handling for further processing.
It has been proposed to handle the cyanuric chloride as a melt or in
solution but such expedients are expensive and often interfere with
further processing.
It has also been proposed that certain oxides of titanium, silicon and
aluminum as well as silicates and carbonates be added to improve the flow
characteristics of cyanuric chloride.
U.S. Pat. No. 3,141,882 particularly recommends the use of gas-phase
produced silicas available under such trademarks as "AER-O-SIL" and
"CAB-O-SIL". Such materials are suitable for cyanuric chloride when used
as a bleach or for the production of aminotriazines. However, for the
synthesis of the optical brighteners generically known under the trademark
TINOPAL.RTM. whose synthesis is described in U.S. Pat. No. 2,762,801,
these materials either interfered with the yields and purity of the
products or interfered with the optical clarity and brilliance of the
brighteners made with such additives.
OBJECT OF THE INVENTION
It is an object of this invention to provide cyanuric chloride compositions
substantially free from dusting and having excellent flowability even
after prolonged storage.
It is another object of this invention to provide cyanuric chloride
compositions which are inexpensive and which provide cyanuric chloride in
a form suitable for use in the synthesis of further products without
reducing the yields or qualities of such products.
It is a further object of this invention to provide cyanuric chloride in a
form that is safe for handling in industrial environments.
SUMMARY OF THE INVENTION
These and other objects are attained for formulating cyanuric chloride into
compositions containing finely divided tribasic calcium phosphate in
amounts of from 0.1 to 5 weight % of the composition. The cyanuric
chloride should preferably have a particle size of less than 30.mu.
(microns) and the resulting composition should have a particle size range
of from 25 to 300.mu. and a preferred range of 50 to 100.mu.. It is
preferred that the composition have a bulk density range of 0.750 g/ml to
0.910 g/ml. When stored, it develops a packed density in the range 0.910
g/ml to 1.100 g/ml yet maintains its flowability.
DETAILED DESCRIPTION OF THE INVENTION
The cyanuric chloride of this invention has the formula:
##STR1##
and is prepared by the trimerization of cyanogen chloride in the
gas-phase.
The solid cyanuric chloride is desublimed as an amorphous powder by cooling
from the vapor phase after the trimerization reaction is completed.
The tribasic calcium phosphate of this invention has the formula Ca.sub.3
(PO.sub.4).sub.2 and is a commercially available additive for use in food
and industrial processing as "tricalcium phosphate". The commercial
material is available in a "reagent" grade. The industrial grade is
suitable for this invention but generally the food grade material is
preferred as it has a more uniform particle size within the preferred
range.
The tricalcium phosphate was compared for the purposes of the present
invention in a series of tests with other commonly used anti-caking agents
including those flow-additives described in U.S. Pat. No. 3,141,882. Only
tricalcium phosphate in the composition according to this invention was
satisfactory in all the tests.
Various recognized flow-improving additives were screened for their
flowability properties vis a vis cyanuric chloride by placing 100 gm of
untreated cyanuric chloride into a clear wide-mouth 16 oz. glass jar and
adding thereto 1.0 wt. % of the flow-additive to be tested. The cyanuric
chloride and the flow-additive were then thoroughly mixed and the sample
jar was inverted. The cyanuric chloride mixture either discharged or
remained compacted, indicating flow or no-flow. Tests were also carried
out at additive concentrations of 2.5 and 4 wt. %. Only calcium carbonate,
magnesium carbonate, sodium phosphate, tricalcium phosphate, fumed silicas
such as AER-O-SIL, CAB-O-SIL and TULLANOX.RTM., stearates of calcium,
magnesium and zinc, magnesium and calcium sulfates and corn starch
imparted satisfactory flow properties at 1% concentration. Of these
additives, when the jars containing the mixtures were stored and inverted
at weekly intervals to determine the flowability, it was found that
calcium sulfate, calcium carbonate, sodium phosphate, corn starch and many
others could not maintain flowability of the cyanuric chloride over four
week periods of such storage conditions.
It was also noted that those additives that improve the flow
characteristics of cyanuric chloride had small particle sizes, all below
about 50.mu. and that no mixtures having particle sizes of greater than
300.mu. provided flowability.
In addition, as cyanuric chloride is an important intermediate for the
synthesis of further economically useful compounds, the cyanuric chloride
compositions of this invention were also tested to ensure their
compatibility in such synthesis by comparing the results achieved with the
various mixtures in actual synthesis of such materials.
The cyanuric chloride/flow additive mixtures were tested in the synthesis
of the herbicide Simazine (2-chloro-4,6-bis-monoethylamino-s-triazine)
according to the general method described at col. 3 (A) of U.S. Pat. No.
2,891,855 substituting monoethylamine for the methylbutylamine used
therein;
and in the synthesis of the optical brighteners of the TINOPAL class, e.g.,
4,4'-bis[4-phenylamino-6-(.beta.-hydroxyethylmethylamino)-1,3,5-triazinyl-
(2)-amino]-stilbene-2,2'-disulfonic acid, as set forth in Example 1 of U.S.
Pat. No. 2,762,801 and, with appropriate substitution of intermediates but
using the same synthesis scheme,
4,4'[4-di-.beta.-hydroxyethylamino-6-p-sulfanilamido-1,3,5-triazinyl-2-ami
no] stilbene-2,2'-disulfonic acid.
Only the tricalcium phosphate-containing composition provided extended
storage capabilities and long-acting flowability and, with respect to the
optical brighteners, did not hinder these synthesis or detract from the
yields or quality of the final products.
In general, the tricalcium phosphate may be added to the cyanuric chloride
at any time to provide a free-flowing composition but to facilitate
handling of the cyanuric chloride it is useful to directly add the
tricalcium phosphate to the cyanuric chloride as it is desublimed from the
trimerization stage. The tricalcium phosphate is blown into the desublimer
by an inert gas, preferably nitrogen, and is supplied in an average
particle size range of 2-50.mu., preferable in the range 5-30.mu..
It is noted that cyanuric chloride desublimed in the absence of the
tricalcium phosphate develops particle size range up to about 300.mu.,
however, when desublimed in the presence of the very finely divided
tricalcium phosphate the resultant composition has a particle size range
of 50 to 150.mu. with an aggregate size of less than 100.mu., i.e., a
distribution range of 50 to 100.mu..
It has also been observed that the composition of this invention has a bulk
density of 0.750 g/ml to 0.910 g/ml and a packed density of 0.910 g/ml to
1.100 g/ml.
Tricalcium phosphate for use as the flow additive in the composition of
this invention is commercially available in the preferred range 5 to
30.mu. as food grade tricalcium phosphate. However, industrial grade
material meeting this preferred range can be obtained.
Thus, the invention supplies compositions containing 95.0 to 99.9% cyanuric
chloride and having 0.1 to 5.0% of tricalcium phosphate distributed
therethrough. The composition is a free-flowing form, capable of prolonged
storage and compatible with the use of cyanuric chloride in further
synthesis to other economically useful materials.
The mode and time of addition of the tricalcium phosphate to the cyanuric
chloride have little to no effect on the flowability or compatibility of
the compositions of this invention provided that the resulting cyanuric
chloride mixture has a particle size of less than 300.mu.. The amorphous
material of up to this larger particle size, when admixed with the
tricalcium phosphate still provides a flowable mass.
EXAMPLE 1
Cyanuric chloride stored at ambient conditions for 14 days, having an
aggregate particle size of about 100.mu., was well mixed with 1.0 weight %
of food grade tricalcium phosphate (aggregate particle size about 7.mu.).
One hundred gm of the mixture was placed into a 16 oz wide mouth sample
jar. The jar was then inverted and the mixture therein was found to be
free flowing. This contrasted with a control sample of 100 gm of the
cyanuric chloride without the additive, similarly packed into the jar,
which upon inversion did not flow but bridged and remained in place with
the bottom of the jar.
The mixture in the jar with 1% of tricalcium phosphate was stored for one
week and then inverted. It still flowed freely within the jar. The
procedure of one week storage followed by inversion was repeated for four
weeks. The composition remained flowable.
EXAMPLE 2
Industrial grade tricalcium phosphate (aggregate size 10.mu.) was injected
via a nitrogen stream into the desublimer portion of a cyanuric chloride
trimerizer. The nitrogen flow was adjusted to add the tricalcium phosphate
at a rate to provide 1% by wt. of tricalcium phosphate to cyanuric
chloride. The mixture had an aggregate particle size of about 75.mu. but
reduced dusting was noted in the bulk handling of the product as compared
with untreated cyanuric chloride.
The resultant composition was tested for flowability by the procedure
described in Example 1. The mixture maintained its flowability even after
four weeks. The cyanuric chloride directly obtained from the desublimer
section of the trimerizer (without tricalcium phosphate) did not even pass
the initial flowability test.
EXAMPLE 3
The portions of the mixture prepared as described in Example 2 were used
for the synthesis of the herbicide and the optical brighteners discussed
above. The resulting products were obtained in good yields and of
satisfactory quality, meeting the standards set for synthesis with
cyanuric chloride without tricalcium phosphate.
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