Legal Question in Landlord & Tenant Law in Illinois

According to Illinois statutes, no. You (or your the buyer if your contract specifies the buyer) are supposed to formally evict if they don't voluntarily vacate/surrender. The biggest problem in this kind of situation, especially where there is a pending sale, can be a dispute over what kind of tenancy was this -- month-to-month, or yearly - owners/landlords of course consider these arrangements short term and tenants like to say they are long-term; it makes a big difference. So your notice ("to vacate") may or may not have been correct for this situation, and under Illinois law the wrong notice VOIDS an eviction (depending on the appellate district you are in). If this will kill or impair your sale, you should bring the situation to an attorney to review - especially the "notice." Also, or alternatively, most sale contracts require seller to deliver possession at closing and if not there is usually a daily "use and occupancy" amount or other cost to seller including a withhold escrow that could erode the purchase price at a penalty rate, and there could be other consequences to you.