Water → HCID 86732903, compound

Participants

Reaction Conditions

Reaction Steps

An open-ended glass tube about 300 mm. long and 75 mm. inside diameter was fitted with a rubber stopper at each end, each stopper having a central opening. A second, smaller glass tube about 300 mm. long but with an outside diameter of 45 mm. was positioned coaxially within the larger tube by insertion through the central openings in the rubber stoppers, and the assembly mounted vertically. The smaller inner tube was closed at its bottom end with a solid rubber stopper. The upper stopper of the outer tube was additionally provided with two smaller holes opening into the bore of the outer tube, one to admit nitrogen gas and the other, itself loosely stoppered, to admit monomer and initiator into the bore of the outer tube. Hot (65°C.) water was circulated through the smaller tube and a 65°C. water bath raised around the outer one. A mixture of chloral (625 ml.) and phenyl isocyanate (29 ml., 4 mole %) was heated to 65°C., mixed with 33 ml. of 3.2% lithium tertbutoxide in cyclohexane and used to fill the annular space between the concentric tubes and the resulting homogeneous mixture allowed to become motionless. Circulation of the hot water in the inner tube was continued but the hot water bath surrounding the outer tube was removed. A -20°C. cooling bath was then raised around the outer tube at the rate of 3 mm. per minute until the cooling bath reached the top level of the quiescent polymerization mixture and completely surrounded it. Cooling of the outer tube was continued for 30 minutes while the inner tube was still being kept warm. After 30 minutes of standing under these conditions, the flow of hot water into the inner tube was stopped and the hot water in the tube was removed by suction, the cooling bath still being in position around the outer tube. After another 30 minute period the stopper closing the bottom end of the inner tube was removed thus allowing the -20°C. bath liquid to enter and fill the center tube. After 30 minutes of thus cooling both the inside and outside tubes, the cold bath was removed and the resulting copolymer product allowed to warm to room temperature overnight before the glass was broken away. The resulting pipe section was void-free and had a smooth outer surface. The inner surface was relatively rough and uneven. Since the manner of cooling caused polymerization to occur from the outer wall inward, the shrinkage which occurred during polymerization caused the polymer to shrink away from the inner tube. The inner surface was machined smooth to give a strong pipe about 200 mm. long, 75 mm. OD, and 50 mm. ID.

Provenance & Evidence