I thought this stuff was just propylene glycol, but it isn’t. It’s relatively cheap (US$3/kg) and so I’m curious about its merits as a coolant. I’m guessing its solvent properties are similar to those of propylene glycol.
Of course it’s miscible with water.
Dow says the pour point is -39°, it supercools, its viscosity drops from 75 centipoise at 25° to 10.9 centipoise at 60°, it boils (“distillation range”) at 228–236°, its vapor pressure at 25° is 2.1 Pa, its flashpoint is 124°, and its specific heat is 2.18 J/g/K. The technical data sheet touts its “low toxicity”. So far so good. Its heat of formation is -628 kJ/mol, but at 134.2 g/mol I’m not sure that means it’s a bad fuel. Thermo Fisher gives its flashpoint as 138°, its autoignition temperature as 310°, and its orl-rat LD₅₀ as 14850 mg/kg; even more astonishing, its LC₅₀ for freshwater fish is “>5000 mg/ℓ, 24h”. So unless they’re confusing it with propylene glycol it’s about as toxic as water.
Perfumers describe it as “virtually odorless with a slight-ethereal-green solvent note.” Monument says it’s “far less hygroscopic than other common glycols” and mentions its use as a coolant. Shell says contact with copper, copper alloys, and zinc must be prevented and that it is not hazardous. The National Toxicology Program (paper) agrees, but notes that giving rats drinking water with 40000 ppm (4%) of it killed them with kidney disease within two years, but the 2% group was fine.