Propylene glycol boiling point

Propylene glycol (boiling point 189°C, density 1.0361) is produced by hydration of propylene oxide in a process similar to that for the production of ethylene glycol by hydration of ethylene oxide. 

The stream from the reaction section is first distilled to remove unconverted propylene, whose recycle, added to the make-up, represents the feed of the first epoxidation stage. Excess propane is also removed by distillation (—50 to 60 trays) to prevent its buildup in tfie synthesis loop. The heavy end of the first column is sent to the purification train for products for which the temperatures cannot exceed 100°C to avoid undesirable degradation. On account of the boiling points at standard pressure of the components present, this makes operation under vacuum necessary. Crude propylene oxide is collected at the top of the first distillation column (50 trays), and r-butyl alcohol at the1bottom, with some hydroperoxide, the catalyst, propylene glycol, aldehydes, esters etc. This stream is sent to a r-butyl alcohol separation column (35 to 40 trays), where the alcohol is recovered at the top. 

Ethyl 9 fluorononanecarboxylate (VII) was found to be even more toxic than ethyl 5 fluoropentanecarboxylate by injection into rabbits, the l.d. 50 for a propylene glycol solution of (VII) being 0-2 mg./kg. Mice and rats were sbghtly more resistant, but exhibited convulsions of the general fluoroacetate type. On account of the high boiling-point of the material, no inhalation experiments were attempted. 2 Fluoroethyl 9 fluorononanecarboxylate (VIII) was found to be no more toxic than the corresponding ethyl ester by injection into mice. Each had a l.d. 50 of about 10 mg./kg. This anomaly is discussed later. 

Dio/s such as ethylene glycol, propylene glycol [57-55-6] and neopentyl glycol are sometimes used as part of the polyols in alkyd formulations primarily for the purpose of regulating the functionality of the reaction system. Their relatively low boiling points, 200°C, requite that special precautionary measures be taken during the resin manufacturing process. 

Propylene glycol (1,2-propanediol) is used as an environmentally friendly engine coolant because it is biodegradable, has a high boiling point, and is miscible with water. 

Conventional oil-based inks contain aromatic hydrocarbons such as toluene or xylene, aliphatic hydrocarbons such as hexane or kerosene, ketones such as methyl ethyl ketone, esters such as ethyl acetate, or solvents such as propylene glycol mono methyl ether acetate. The problems with such inks are that their fast drying time due to low boiling points or flash points are likely to clog up the nozzle. 

BP = boiling point or range ST = surfaoe tension at 20 °C, at 25 °C ER = relative evaporation rate (diethyl ether = 1) FP = flash point by olosed cup PGMEAc propylene glycol monomethyl ether acetate (Note Properties are selected from different resources without claiming to be complete and accurate)... 

An appreciable dried polymer film (skin) is very often observed on the top of a latex product during storage at relatively high temperature. This is attributed to the inevitable evaporation of water from latex products. Addition of a small amount of hydrophilic cosolvents such as propylene glycol can increase the boiling point of the aqueous medium and, thus, retard the formation of the undesired dried polymer film. 

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