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29 lis 2015 · If BF 3 stripped an H atom off a water molecule, it would technically leave OH-in the solution, and actually raise the pH instead. BF 3 is a Lewis acid. Why would it raise the pH?
BUT BF3 reacts with the lewis base OH- to form H[BF3OH] and thus affects the pH of the solution - effectivly making the solution more acidic. A similar effect is seen in the boric acid, B(OH3), which forms H[B(OH)4] in water.
All three lighter boron trihalides, BX 3 (X = F, Cl, Br) form stable adducts with common Lewis bases. Their relative Lewis acidities can be evaluated in terms of the relative exothermicities of the adduct-forming reaction.
BF3 is a non-flammable compressed gas packaged and shipped in cylinders under high pressure. It is one of the strongest Lewis acids, which are also known as electron pair acceptors. In gas form, it reacts with chemicals containing oxygen, nitrogen, sulfur, and other electron pair donors to form addition or coordination compounds.
Boron trifluoride is a colorless gas which has a persistent, irritating, acidic odor and which hydrolyzes in moist air to form dense white fumes. It is shipped as a nonliquefied compressed gas at varying pressures up to 2000 psig (13 790 kPa).
Here are some key properties of this colorless gas: At standard temperature and pressure, BF3 is a non-flammable diatomic gas. It condenses to a liquid at -100°C and freezes at -127°C. The B-F bonds are very strong, making BF3 stable and resistant to decomposition below 500°C.
BF3-Methanol provides a convenient methanol-catalyst system which, when used in excess with heating, quickly and quantitatively converts carboxylic acids to their methyl esters.
