verbs - I demand they do… / I demand them to…

According to practically every grammar I've encountered, "I demanded them to leave" is incorrect English. I've quite literally spoken like this all my life; I don't know if it's a dialectal thing (I'm from the NYC area), or if it's simply an error of my own idiosyncratic speech. However, as someone who teaches English Language, I don't want to make any mistakes concerning my pupils' language acquisition. It's extremely important to me that I clarify this subject before I continue teaching it… I'm afraid to create a generation of poor English-speakers!

Does anyone else speak this way? Is

My mother is demanding I clean my room before I leave

and

My mother is demanding me to clean my room before I leave

vastly different? Is one simply incorrect?

Answer

I think what John Lawler was getting at with his response is what the direct object of "demand" is allowed to be. (Definitely an interesting read, John. Thank you.)

In the case of "demand", the object should be an action or the result thereof. Let's use your initial construction.

I demanded them to leave.

Certainly, the direct object appears to be "them", but the sentence wouldn't make any sense without "to leave". Here's an alternative, and perhaps the source of your confusion.

I demanded of them that they leave.

So, we have them appearing twice: as them and as they. It sounds wordy to have both, so we can choose one. If we choose to keep the first, the verb becomes an infinitive without a subject.

I demanded of them to leave.

If we choose to keep the second, we simply take out the entire prepositional phrase in which they first appear.

I demanded that they leave.

This can be condensed further.

I demanded they leave.

Let's look at your other examples. Here is the statement fully realized.

My mother is demanding of me that I clean my room before I leave.

Technique #1: Remove the second subject and convert the verb to an infinitive.

My mother is demanding of me to clean my room before I leave.

Technique #2: Remove the first prepositional phrase.

My mother is demanding that I clean my room before I leave.

Technique #2b: Remove the first prepositional phrase and the relative pronoun.

My mother is demanding I clean my room before I leave.