Connecting standpipe to 1 1/2" brass waste pipe?
Based on you answer in the comments my answer would be. 

Presumably if it was a sink then its vent was provided by the nearby main stack so you should be able to put a san-tee on it and p-trap into the san-tee. BUT it could have had a vent coming of the original san-tee and connecting elsewhere to the stack ? 

You want the san-tee low so that you have room enough to put a tall vertical pipe on top of the P-trap so the washing machine discharge does not splash back.  

I would, since you do not know for sure if it is vented to the main, stack run pipe up off of the top of the san-tee  as high as you can ( at least a foot or more if you can above the top of the top of the washing machine drain pipe ) and put an air admittance valve on top of that.