Definitely agree with what everyone else is saying, but it really isn't necessary to put them in their crib for their "time out" - even though they don't have a negative association with it now, they certainly could soon.
When DS hits you or someone else in the face, he must be put down immediately, saying something like "Mama doesn't like it when you hit" - but in your normal tone of voice. Distance yourself from DS for 30 seconds to a minute, and then come back and say again "Mama doesn't like it when you it. It's not ok to hit" and then explain to him that soft touches/gentle touches/whatever are ok, and guide his hand on your arm, face, whatever to show him how you would like him to touch you. - This will not work immediately, but if you are consistant with him every time it happens, it shouldn't take long for him to catch on.
Raising your voice and slapping him on the hand is not necessary to stop his behavior, just some gentle guidance. Toddlerhood can be tough, but it is such a great age as well.