You can try to purify your coke with a two-step extraction process that you can probably find on BlueLight, but this would take more time and you would loose precious cocaine in the process so I wouldnt bother unlesss I had larger amounts.
If you don't want to use baking soda you could use pure ammonia, which is flammable and likely not available at your local grocery store.

The chemical reaction that would be taking place is the cocaine base being liberated from its HCl salt, since Cocaine HCl (coke) will burn up and be wasted if you try to smoke it as it is.
If you have relatively pure coke, making crack from it will probably be easier. I was cooking up some crack a few days ago and noticed some browning and sweet smell, indicating the presence of sugar as a cut but this didn't interfere with the process too much.
True 'crack' is made using baking soda (listen to the sound of crack being smoked). Any leftover baking soda will simply turn to carbon dioxide when it is heated.