Need help to create 301 dynamic redirect urls

[jennypretty]

Hello,

I have one question about is it possible to create dynamic 301 redirect urls.

I have a dating site and the url format is like /dating/united_states_singles/. A few months ago, I changed it to /free-dating/united_states/ (added free and removed singles). When I checked on Google webmaster tool, both URLs (old and new) are indexed, which create duplicate title and description tags.

Is it possible to create 301 redirect for all old urls to new urls format?

Thanks very much!
Have a nice day!

[magzjamz]

Instead of doing a 301 redirect, I would remove the old url in Webmaster Tools.

[jennypretty]

So, there are around 2000 urls so I can't manually do that.
Should I use robots.txt to disallow old urls.

Example:
User-agent: *
Disallow: domain/dating/

Thanks.