Process for preparing a mixture of amino-containing...

Details Process for preparing a mixture of amino-containing... Process for preparing a mixture of amino-containing...

2000-07-12

2001-07-24

Vollano, Jean F. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Phosphorus esters

C558S157000

Reexamination Certificate

active

06265599

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a process for preparing a mixture of amino-containing phosphazenes that can be used simultaneously as a curing agent and a flame retardant for resins, particularly to a water-free process for preparing an mixture of amino-containing phosphazenes.
BACKGROUND OF THE INVENTION
Phosphazenes are compounds that contain —P=N— bonds and have a general formula [NPR′R″]
n
, wherein n is ≧3. Such compounds have thousands of derivatives along with a change in R′ and R″. In addition to a variation in R′ and R″, the structures of the phosphazenes can be classified into cyclic compounds and linear compounds. When n=3, the compounds become benzene-like hexagonal planar compounds. When n=4, the compounds become octangular cyclic compounds. Among the identified cyclic phosphazenes, the maximum n value is 10. Phosphazenes with n≧3 can also exist in a linear form. Phosphazenes have always been viewed as a potential flame retardant in view of a synergistic effect of P and N elements. When R′ or R″ is a group containing an active hydrogen (such as amino or hydroxyl), such phosphazenes can even be used to cure a resin having functional group(s) that can react with an active site, such as polyurethane having isocyanate terminals and epoxy resins. A typical example of the amino-containing phosphazene that can be used as a curing agent and a flame retardant for the polyurethane and epoxy resins, has a structure of N
n
p
n
(NH
2
)
x
(OR)
2n−x
, wherein 1≦x<2n, and R is phenyl or C3-C6 alkyl. The conventional processes for preparing such amino-containing phosphazenes basically can be classified into two types. The first type of preparation process comprises amination and then esterification; and the second type of preparation process comprises esterification and then amination. The following Scheme 1 shows an example of the first type, in which N
3
P
3
(NH
2
)
2
(OC
3
H
7
)
4
is synthesized:
In Scheme 2, the amination step can only be completed under a pressurized state, which increases the complexity and the safety concerns of the process.
The above-mentioned processes all have a defect of having too many operational steps thereof. Take Scheme 1 as an example:
Step 1: amination;
step 2: separating the organic phase from the aqusous phase after the amination;
step 3: removing the organic solvent by evaporation, thereby obtaining N
3
P
3
(NH
2
)
2
Cl
4
;
step 4: reacting the intermediate product N
3
P
3
(NH
2
)
2
Cl
4
with NaOC
3
H
7
under refluxing;
Step 5: after reaction, washing off NaCl with water; and separating the organic phase from the aqueous phase;
Step 6: drying off residual moisture in the organic phase; and
Step 7: removing the organic solvent from the organic phase by evaporation, thereby obtaining the product.
SUMMARY OF THE INVENTION
The present invention provides a process for preparing a mixture of amino-containing phosphazenes having the following general formula (I) via simultaneous amination and esterification by reacting a (NPCl
2
)
n
phosphazene mixture with NH
3
and HOR in the presence of a tertiary amine catalyst:
N
n
p
n
(NH
2
)
x
(OR)
2n−x
  (l)
wherein n≧3, 1≦x<2n, and R is phenyl or C3-C6 alkyl.
In addition to simultaneously carrying out amination and esterification, the process according to the present invention also simultaneously performs a regeneration of the catalyst. Therefore, the invented process not only greatly reduces the operational steps, but also the reaction time. Moreover, the invented process is a water-free process without the problem of a large quantity of waste water and sodium chloride. Furthermore, a by-product, ammonium chloride, of the invented process, can be recovered in a subsequent process.


REFERENCES:
patent: 3193571 (1965-07-01), Bilger
patent: 3939228 (1976-02-01), Kao
patent: 4618691 (1986-10-01), Medina et al.
patent: 5105001 (1992-04-01), Goins et al.
CA:112:119103 abstract of Phosphorus, Sulfur Silicon Relat. Elem. by Fincham et al 41(3-4) pp 317-22, year 1989.*
CA:111:154982 abstract of Han'guk Somyu Konghakhoechi by Jeong et al 25(7) pp 553-60, year 1988.*
CA:108131952 abstract of J. Agric. Food Chem. by Peters et al 36(2) pp 384-390, year 1988.

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