Donna: Laura Gianotta brings up the point of NJ Department of Community Affairs rules. Frankly, I have no knowledge of multiple unit apartments in this regard but I suspect that, in the final analysis, the owner of a property can sell a property as they please, with no involvement of the tenants. If there were a clause in the lease that the tenant has the right to purchase, it might become necessary to give notice but that would be a rare case and the landlord could still sell it without doing so and the tenant would have the right to pursue a civil action outside of Community Affairs jurisdiction, I would think. (We're getting into rules and legal stuff that get into the legal counsel area, beyond the Realtor's realm.
If a new owner, who is now de facto new landlord, takes over, the tenant has the rights that they had with the old landlord. An existing lease would be part of what was purchased, with all it's benefits (a guaranty of income) and handicaps (inability to raise the rent until the lease expires or remove the tenant early.)
The bottom line is, I believe, that the owner does not have to get the tenant's permission to sell or advise him of the sale unless special conditions apply.