October Novel Prep Challenge

It depends on the way you portray the company. If you wrote about Coca-Cola stealing people's souls, you might want to find another beverage name to label the company that doesn't exist. The corporation has enough money to cease and desist the publication.

On the other hand, you could be promoting the company with what you're saying. Is your tone toward the company favorable? Would they appreciate their name being used in this way? Do you want to contact the company and ask permission? **Found references that say you don't need to get permission for trademarks, but if you'd feel uncomfortable asking someone to use their name because of how you use them in your book, I wouldn't do it.

http://www.rightsofwriters.com/2010/12/can-i-mention-brand-name-products-in-my.h...
http://www.dailywritingtips.com/use-of-trademark-names-in-fiction/