[AllylicAzideUMN]

Out of complete curiosity, I'm wondering the relevant properties of a solvent that determine the temperature of its corresponding dry ice bath. Essentially, why is a dry ice/pyridine bath -42 centigrade while a dry ice/acetone bath -78 centigrade? I know dry ice dissolves in the solvent of interest, so I'm guessing CO2 solubility plays a role. Any further insights?

[rolnor]

Pyridine has melting point -42°C. You can get very cold mixtures if you mix nitric acid and dry ice, I dont remember exact temperature though.