Generating borane from the reaction of iodine + sodium borohydride in THF. When the color of the iodine fades it is ready. The reaction goes as seen here: So what happens here? First, iodine is reacting with one sodium borohydride, so you get borane, sodium iodide, and hydrogen iodide. Then hydrogen iodide is reacting with another sodium borohydride, so you get another borane and another sodium iodide, plus some hydrogen.