C3H6 42.08

Cyclopropane.
Cyclopropane [75-19-4].

Packaging and storage— Preserve in cylinders. [note—Maintain cylinders of Cyclopropane at 25 ± 2 for not less than 6 hours prior to withdrawing specimens for the tests and assay, and correct the results to 25 and 760 mm of mercury.]

Labeling— The label bears a warning that cyclopropane is highly flammable and is not to be used where it may be ignited.

Acidity or alkalinity— Add 0.3 mL of methyl red TS and 0.3 mL of bromothymol blue TS to 400 mL of boiling water, and boil the solution for 5 minutes. Pour 100 mL of the boiling solution into each of three color-comparison tubes marked A, B, and C, respectively. To tube B add 0.20 mL of 0.012 N hydrochloric acid, and to tube C add 0.40 mL of 0.012 N hydrochloric acid. Insert the stopper in each of the tubes, and cool them to room temperature. Pass 2000 mL of Cyclopropane through the solution in tube B at a rate requiring about 30 minutes for the passage of the gas: the color of the solution in tube B is no deeper orange-red than that in tube C and no deeper yellow-green than that in tube A.

Carbon dioxide— Place the container so that when its valve is opened, the gaseous phase can be sampled. Connect one end of a carbon dioxide detector tube to the container valve, and the other end to a gas flow meter. Pass 1000 mL of the Cyclopropane through the tube at a suitable rate: the indicator change corresponds to not more than 0.03%.

Halogens— Provide a 500-mL flask with a tightly fitting two-hole stopper. Through one opening pass a delivery tube bent at right angles and extending just beyond the lower surface of the stopper. Through the other opening insert a capillary tube bent at right angles and having a bore of 1 ± 0.2 mm, in the same manner. Place in a 50-mL cylinder, having an internal diameter of 2 ± 0.25 cm, 40 mL of a solution containing 850 mg of sodium carbonate in 1000 mL of water. Provide the cylinder with a two-hole stopper, and through one opening pass a right-angle delivery tube, having a bore of 3 ± 0.5 mm, to within 2 mm of the bottom of the cylinder. The end of the delivery tube that extends out of the cylinder is provided with an enlargement 8 ± 0.5 cm long having an internal diameter of 2 ± 0.25 cm. Through the other opening in the stopper pass another right-angle delivery tube, having it extend just below the surface of the stopper. Collect 500 mL of Cyclopropane in the flask. By means of hydrostatic pressure, applied through the delivery tube, force the gas through the capillary tube, the water used being previously saturated with Cyclopropane. Ignite the gas, place the enlarged end of the delivery tube, connected with the cylinder, around the flame, extending the flame one-third of the way into the enlargement. Apply suction to the shorter delivery tube connected with the cylinder, thus drawing the spent gases through the sodium carbonate solution, the period of ignition of the 500 mL of Cyclopropane requiring approximately 30 minutes. Make any necessary correction for the amount of halogen in the volume of air used for the ignition of the gas. Transfer the sodium carbonate solution to a 500-mL volumetric flask, and rinse the cylinder thoroughly, collecting the rinsings in the flask. Dilute the solution with water to volume, and mix. To a 50-mL aliquot add sufficient nitric acid to make it acid to litmus paper, and then add 1 mL of acid in excess. Prepare a blank containing 0.50 mL of 0.0012 N hydrochloric acid and 4 mL of the sodium carbonate solution in 46 mL of water, acidify to litmus with nitric acid, then add 1 mL of acid in excess and 1 mL of silver nitrate TS to each solution: after 5 minutes any opalescence in the solution representing the Cyclopropane does not exceed that in the blank (0.02% as chloride).

Propylene, allene, and other unsaturated hydrocarbons— Place the container so that when its valve is opened, the gaseous phase can be sampled. Connect one end of an olefin detector tube to the container valve, and the other end to a gas flow meter. Pass the Cyclopropane through the detector tube at a suitable rate: the color of the indicating layer of the tube contents matches the color standard after the passage of not less than 400 mL of Cyclopropane (0.9% as propylene).

Assay— Place the container so that when its valve is opened, the gaseous phase can be sampled. Withdraw 100 mL of Cyclopropane, accurately measured in a gas buret previously filled with mercury and equipped with a leveling bulb at the lower end. Connect one arm of the buret stopcock to a pipet that previously has been filled with sulfuric acid. By appropriate manipulation of the stopcock and the leveling bulb, transfer the gas between the pipet and the buret, bringing about sufficient contact of the gas with the acid to reduce the volume of unabsorbed gas to a minimum as measured in the buret. Not more than 1.0 mL of gas remains.

Topic/Question	Contact	Expert Committee
Monograph	Kahkashan Zaidi, Ph.D. Senior Scientist 1-301-816-8269	(AER05) Aerosols05

USP32–NF27 Page 2042