Quinoline-d7 is a deuterated compound of Quinoline. Quinoline has a CAS number of 91-22-5. Quinoline is found in alcoholic beverages. Quinoline is an alkaloid from various plant species including Mentha species. Also present in cocoa, black tea, and scotch whiskey. Aged samples, if exposed to light, become yellow and later brown. Quinoline is only slightly soluble in cold water but dissolves readily in hot water and most organic solvents.