Specific heat properties for cooling are largely over-rated.
For example, the SHC of water is 4186J/kgC. For ethanol it's 2453J/kgC. Water has a density of 1. Ethanol 0.8.
Per 1 litre volume, water has a heat capacity (HC) of 4186J/lC. For ethanol, it's ~1960J/lC.
i.e. ethanol has roughly half the thermal capacity of water per volume.
However, assuming a 100W heat load and 6LPM flow rates, the water will heat up by (100/4186) / (6/60) = 0.24C as it flows through the block, and ethanol by ~0.51C.
i.e. At 6LPM flow rates the difference between ethanol and water is at best 0.27C based on SHC of each substance alone. Given sufficient flow rates, one liquid can have a fairly crap thermal capacity compared to water and still not be noticably worse (based on specific heat capacity alone).
Where it gets important for heat transfer is the relative viscosities and rate of thermal conduction for the two liquids. Less viscous liquids will have thinner boundary layers and will become more turbulent more easily. The thermal conductance of the liquid determines how hard it is for the heat in the metal to pass through that boundary layer into the greater liquid mass. i.e. a liquid with very low viscosity and low conductance can be just as good as a syrupy liquid with high thermal conductance.
What we want overall is a liquid that has a thermal mass per volume of no lower than about 1000J per liter-C, and has a lower viscosity than water, and a higher thermal conductance than water.
If you chemists can find such a liquid, then that would be the better liquid to use than water.