US 11,912,666 B2
Synthesis of 6-oxo-1,4,5,6-tetrahydropyridizin-3-carboxylic acid
Robert Blaskovic, Marietta, GA (US); Rudolfo Martinez, Santa Fe, NM (US); Nathan P Martinez, Santa Fe, NM (US); and Cliffford J Unkefer, Los Alamos, NM (US)
Filed by Millennium Enterprises, Inc., Maarietta, GA (US)
Filed on May 17, 2021, as Appl. No. 17/322,521.
Prior Publication US 2022/0372002 A1, Nov. 24, 2022
Int. Cl. C07D 237/04 (2006.01)
CPC C07D 237/04 (2013.01) 3 Claims
 
1. A method for producing 6-oxo-1,4,5,6-tetrahydropyridazine-3-carboxylic acid, comprising the steps of:
providing a system including a reaction tank, a powder funnel coupled to the reaction tank, three three-way valves A, B, and C for directing the flow of liquid, at least one pump for circulating liquid, a metering valve, a filter bag, and a filtrate tank;
set the three-way valves A, B, and C to circulate liquid out of the bottom of the reaction tank and back into the top of the reaction tank;
add deionized water to the reaction tank and start the pump;
add 2-ketoglutaric acid into the reaction tank through the powder funnel, wherein the 2-ketoglutaric acid and deionized water circulates until they become mixed into a solution;
add hydrazine sulfate to the solution in powder form at the reaction tank using the powder funnel, wherein the solution with hydrazine sulfate added created a heterogenous mixture;
allow the heterogenous mixture to circulate through the reaction tank for more than an hour;
check a reaction level of the solution for free hydrazine after it has been allowed to circulate;
if the reaction level is less than 5 ppm, the reaction is complete, otherwise continue with circulation through the reaction tank;
if the reaction level is less than 5 ppm, set three-way valve A so flow of the solution both returns to the reaction tank and also partially goes into the filter bag and use a metering valve to limit flow of liquid into the filter bag such that a portion of the flow is returned to the reaction tank; and
after the filter bag is devoid of liquid, valves A, B and C are set to flow filtrated liquid from the filtrate tank back to the reaction tank, where the solution as filtered can be moved into a reaction flask via an output port.