You say 'put it on', but not 'put on it' (although you can say 'put on the coat'. I've once heard this is caused by some linguistic reason.But, how about 'put some of it aside'?
Can we say 'put aside some of it'?
This seems to be a question of usage. For the phrasal verbs known as "separable phrasal verbs," we generally use three different forms. Here are examples of those forms using the phrasal verb "put on."
1. Noun in the middle of the phrasal verb:
I put my hat on.
2. Noun at the end of the phrasal verb:
I put on my hat.
3. Pronoun in the middle of the phrasal verb:
I put it on. (This assumes that we know from the context that "it" is "hat.")
The one form that is not considered natural is having the pronoun at the end of a separable phrasal verb:
I put on it.
I don't know a real grammatical reason for this--I've always assumed it was a matter of usage.
Your example ("put aside some of it"), however, doesn't sound bad to my ear. (It seems to me that the use of the indefinite pronoun "some" sounds better than the use of the definite pronoun "it" by itself.) Still, I think "put some of it aside" sounds more natural than "put aside some of it," and I'm sure sure it would be considered the proper form by grammarians.
