Check for melting point, boiling point, and NMR spectra

The meting point should be 14-17 °C, the boiling point 232 °C. You can also run an IR to check if there is no signal from i-PrOH (around 3400-3300 cm1).

If reaction is failing, prepare fresh TTIP and use, else recrystallize and use in the reaction.

it is clear liquid ( check by flashing a light through it if you have taken in glass vial). generally it becomes cloudy as also some white ppt after taking moisture. Sigma Aldrich supply it in large plastic can (~1 Lit). Tranfer the liquid in a small glass bottle with rubber septum according to your rquirement and when you finish it again refill it from large can. This is the way we use Titanium isopropoxide and we have never found any problem.