can my couch be saved with Vinegaroon?

[teaners]

A friend of mine threw up on my brown leather couch and it seems permanently stained. I used baking soda to get the smell out and tried the normal leather cleaning products to no avail. I was thinking of vinegaroon'ing the whole couch to see if I could just make it black. What are your thoughts? I saw on here that I should try to avoid adding oxygen to the vinegaroon so perhaps I should brush it on vs using a spray bottle? Does the neutralizing with baking soda eliminate the vinegar smell? Should I add the baking soda it to the vinegaroon solution it's self or make a rinse afterwards? 

 

Thanks for your time. I know I have a lot of questions,

Kristina