A Dull Dull Word

Question

Here is your riddle for the day!

I am a five letter word.

With five I'm made of three

With four I might give a raise

With three I'm a good friend

With two I like to react

What word am I?

Answer 1

Are you

Brown?

With two I like to react

Br, or Bromine, is highly reactive.

With three I'm a good friend

A Bro is a good friend.

With four I might give a raise

A Brow might be raised ("raised eyebrows")

With five I'm made of three

Brown as a color could be said to be made of the three primary colors (red, blue, yellow): mixing all creates brown.

Title:

Brown could be said to be a dull color