Kasha–Vavilov rule, 802 katal, 803 Kekulé structure (for aromatic compounds), 803 kelvin, 803 ketals, 803 ketazines, 804 ketenes, 804 ketenimines, 804 ketimines, 804 keto, 804 keto carbenes, 805 ketoaldonic acids, 805 ketoaldoses, 805 ketones, 805 ketoses, 806 ketoximes, 806 ketyls, 806 kilo, 807