Abstract: On January 31, 2006, a runaway reaction occurred at Synthron, Inc., while employees were making Modarez MFP-BH. The polymerization reaction included toluene, cyclohexane, n-butyl acrylate, and benzoyl peroxide. According to the employer's records, there were 2,689 pounds of the solvent blend and 1,923 pounds of N-Butyl Acrylate in a Pfaudler reactor (M-1). Two 55-gallon drums and one 330-gallon IBC tote were positioned in front of reactor M-1. The containers held a solvent blend of toluene, cyclohexane, and benzoyl peroxide. At the time of the incident, the contents of one of the drums and a portion of a second drum had been transferred to the M-1 reactor. Employee #1 walked away from the reactor, intending to turn a valve on the M-5 reactor to begin a nitrogen purge and move the contents of M-5 to M-1. While walking down a stair to perform this task, Employee #1 heard a loud, high-pitched sound. He immediately went back up and observed the Teflon 18 in. envelope gasket from M-1 hanging down from the manway and vapors coming through the opening. Other employees began to hear the sound. After Employee #1 observed the vapors being emitted, he walked outside and met other employees outside the production door, on the Northwest side of the building. Employee #2 was operating a forklift inside the drumming area when he heard the sound. He left the area and met with Employee #3 and Employee #4. They walked up to the Northwest side of the building. Employee #5 instructed Employee #3 to go get the Plant Manager. Employee #5 then donned a full-face respirator and entered the building to turn on the chill water to the reactor. After a few seconds, Employee #5 returned after failing to obtain a good seal on the respirator and smelling vapors. Employee #1 then donned the respirator and went inside the building. Employee #3 and Employee #6 walked up and joined the other employees outside the production door. When Employee #1 exited the building, an explosion occurred. Twelve employees and two bystanders sustained various injuries. Five of the employees were hospitalized with various injuries, and one died later of burns.