Lewis Acid is a species that contains an atom that is at least two electrons short of a closed outer shell.. how is AlCl3 a Lewis Acid then?
Don't understand why AlCl3 is a lewis acid when al is bonded to all three cl with single bond and each CL has 3 pairs of lone pairs around it.
2006-12-13 03:37:37 · 5 answers · asked by AUNIDLY 1 in Science & Mathematics ➔ Chemistry
I think it's the Al, not the Cl's, that is acidic.
2006-12-13 03:42:28 · answer #1 · answered by Amy F 5 · 0⤊ 0⤋
Let's remember that a LEWIS acid is defined as an ELECTRON PAIR ACCEPTOR. That is, as you point out, in the monomer, there are 3 bonds, or 6 e's. That is why AlCl3 usually dimerizes to Al2Cl6. It accepts the electron pair from an additional Cl- (whether free, or attached to/part of another AlCl3 monomer). Each Al "thinks" it has FOUR Cls around it. Even the monomer reacts readily with Cl- to give AlCl4-.
2006-12-13 03:48:46 · answer #2 · answered by ? 4 · 0⤊ 0⤋
General definition of a Lewis acid is that it is an electron pair acceptor. Aluminum chloride becomes a Lewis acid by accepting another Cl- ion. AlCl3 + Cl- --> AlCl4-1 Notice that it takes a negative charge when it accepts the other chloride ion. This property is especially important in its reaction with organic chlorides like an alkyl halide (CH3-CH2-CH2Cl) that will react with benzene in the presence of aluminum chloride.
2006-12-13 03:47:44 · answer #3 · answered by docrider28 4 · 0⤊ 0⤋
here Al is short of 2 e- that is why AlCl3 is a lewis acid
2006-12-13 03:50:34 · answer #4 · answered by Gunjit M 2 · 0⤊ 0⤋
that's true, but has a good ammount of positive charge on the Al atom which makes it a great target (electrophile) which also makes it a good lewis acid. just remember a lewis acid is an electron acceptor.
2006-12-13 05:42:04 · answer #5 · answered by shiara_blade 6 · 0⤊ 0⤋