Can I use an adapter to plug a 230v air conditioner into a 120v outlet?
So you have a 120V outlet on the wall, and a 230V air conditioner? If so, then probably not. Those "adapters" (assuming the kind used for travel) are intended to power SMALL appliances, like shavers, cell phone chargers, MAYBE a hair dryer. An Air Conditioner likely requires WAY more power than those devices are good for. That's why it is designed for 230V; it is too much power for a standard 15A 120V outlet.

But you can check to make sure. Look on the nameplate of the Air Conditioner for the wattage. A standard 120V 15A outlet is good for 1800W maximum, assuming a "non-continuous" load and NOTHING else on the same circuit. But worse than that is that most of the travel type power adapters are rated for 1300-1400W MAXIMUM. If your A/C unit draws more than that, then it can't work without risking a fire.