(4R,6S)-6-Methyl-7,7-dioxo-5,6-dihydro-4H-thieno[2,3-b]thiopyran-4-ol (CAS RN 147128-77-6) with a purity by weight of 94 % or more

1. Except where the context otherwise requires, the headings of this chapter apply only to: (a) separate chemically defined organic compounds, whether or not containing impurities; (b) mixtures of two or more isomers of the same organic compound (whether or not containing impurities), except mixtures of acyclic hydrocarbon isomers (other than stereoisomers), whether or not saturated (Chapter 27). 2. This chapter does not cover: (a) goods of heading 1504 or crude glycerol of heading 1520; (b) ethyl alcohol (heading 2207 or 2208); (c) methane or propane (heading 2711); (d) the compounds of carbon mentioned in Note 2 to Chapter 28; (e) immunological products (heading 3002); (f) urea (heading 3102 or 3105); (g) colouring matter of vegetable or animal origin (heading 3203), synthetic organic colouring matter, synthetic organic products of a kind used as fluorescent brightening agents or as luminophores (heading 3204), or dyes or other colouring matter put up in forms or packings for retail sale (heading 3212); (h) enzymes (heading 3507); (ij) metaldehyde, hexamethylenetetramine or similar substances, put up in forms (for example, tablets, sticks or similar forms) for use as fuels, or liquid or liquefied-gas fuels in containers of a kind used for filling or refilling cigarette or similar lighters and of a capacity not exceeding 300 cm3 (heading 3606); (k) products put up as charges for fire-extinguishers or put up in fire-extinguishing grenades, of heading 3813; ink removers put up in packings for retail sale, of heading 3824. 3. Goods which could be classified in two or more headings of this chapter are to be classified in the heading which occurs last in numerical order among those which equally merit consideration.