Mo. Rev. Stat. § 526.050

When it shall appear by the petition that the plaintiff is entitled to the relief demanded, and such relief, or any part thereof, consists, in restraining the commission or continuance of some act of the defendant, the commission or continuance of which, during the litigation, would produce injury to the plaintiff, or when, during the litigation, it shall appear that the defendant is doing, or threatens or is about to do, some act in relation to the plaintiff's rights respecting the subject of the action, and tending to render the judgment ineffectual, a temporary injunction may be granted to restrain such act.