"to not do" or "not to do"?
We have always been told to use "not" before "to" when we want to make a negative infinitive. Like "I told you not to do so!"
As I have noticed that in dictionaries, the structure "to not" is used instead of "not to".
Are they exactly the same? Is "to not" a structure that just a native speaker can use?
(As we have never been told to use that)

Question

"to not do" or "not to do"?
We have always been told to use "not" before "to" when we want to make a negative infinitive. Like  "I told you not to do so!"
As I have noticed that in dictionaries, the structure "to not" is used instead of "not to".
Are they exactly the same? Is "to not" a structure that just a native speaker can use?
(As we have never been told to use that)

Answer

There is a stricture against the so-called "split infinitive", which dictates something like "I told you not to do so!" in your example. It's a silly rule, and no one pays much attention to it anymore. At the same time, students preparing for tests should be aware.