Morphology control of substituted diacetylenic monomers for shelf life monitoring systems
View Patent ↗A system for recovering a diacetylenic monomer shelf life monitoring compound of reduced particle size and narrow size distribution range which comprises quenching a solution of the monomer by mixing the solution in a lower temperature quenching fluid having a base temperature which is at least about 30° C. below the nominal temperature at which the monomer compound recrystallizes from solution, the mixing being effected in such a manner as to limit the resulting quenching mixture temperature to one which is not higher than a maximum of about 15° C. above the quenching fluid base temperature.
1. A process for recovering a diacetylenic monomer compound which comprises effecting recrystallization of said monomer compound by means of quenching a heated solution thereof in a lower temperature miscible quenching fluid characterized in that
a) said quenching fluid is initially cooled to a base temperature which is at least about 30° C. below a nominal temperature at which said monomer compound recrystallizes from the solution; and
b) said monomer solution is mixed with said cooled quenching fluid in such a manner as to limit the resulting quenching mixture temperature to one which is not higher than a maximum of about 15° C. above said base temperature,
thereby achieving recrystallization of said monomer compound as particles of reduced size having a narrow range of size distribution.
2. A process according to claim 1 characterized in that
a) said quenching fluid is contained in an externally cooled quenching vessel;
b) a first portion of said monomer solution is mixed into said quenching fluid in an amount which is insufficient to increase the temperature of said resulting quenching mixture above said maximum temperature;
c) said resulting quenching mixture is cooled in said quenching vessel; and
d) a subsequent portion of said monomer solution is mixed into said resulting quenching mixture in an amount which is insufficient to increase the temperature of the accumulated quenching mixture above said maximum temperature.
3. A process according to claim 2 wherein additional subsequent steps of cooling and mixing are effected.
4. A process according to claim 2 wherein said monomer compound is 2,4-hexadiyn-1,6-bis (ethylurea), said base temperature is about 0° C., and said maximum temperature is about 15° C.
5. A process according to claim 2 wherein said monomer compound is 2,4-hexadiyn-1,6-bis (ethylurea), said base temperature is about −15° C., and said maximum temperature is about −5° C.
6. A process according to claim 2 wherein said monomer compound is 2,4-hexadiyn-1,6-bis (ethylurea), said base temperature is about −25° C., and said maximum temperature is about −15° C.
7. A process according to claim 1 characterized in that
a) said quenching fluid is contained in an externally cooled quenching vessel; and
b) said monomer solution is mixed into said quenching fluid at a rate which is insufficient to increase the temperature of the accumulating quenching mixture above said maximum temperature.
8. A process according to claim 1 characterized in that
a) said quenching fluid is contained in an externally cooled quenching vessel;
b) said monomer solution is mixed into said quenching fluid at a substantially constant rate; and
c) said quenching vessel is cooled at a rate which is sufficient to prevent the temperature of the accumulating quenching mixture from increasing above said maximum temperature.
9. A process according to claim 8 wherein said monomer compound is selected from the group consisting of 2,4-hexadiyn-1,6-bis (ethylurea), 2,4-hexadiyn-1,6-bis (propylurea), a 2:1 co-crystallization of 2,4-hexadiyn-1,6-bis (ethylurea) and 2,4-hexadiyn-1,6-bis (propylurea), and a co-crystallized mixture of asymmetric synthesis comprising 2,4-hexadiyn-1-ethylurea-6-propylurea.
10. A process according to claim 1 characterized in that
a) said monomer solution and said quenching fluid are contemporaneously introduced into and mixed in an externally cooled quenching vessel; and
b) said quenching vessel is cooled at a rate which is sufficient to prevent the temperature of the accumulating quenching mixture from increasing above said maximum temperature.
11. A process according to claim 1 characterized in that
a) said monomer solution and said quenching fluid are contemporaneously delivered to a mixing site at respective rates which ensure that said maximum quenching mixture temperature is not exceeded.
12. A process according to claim 11 wherein said quenching mixture is delivered to a recrystallized monomer compound recovery apparatus.