2931.59.00.60 - Containing a phosphorus atom to which one methyl, ethyl, n-propyl or isopropyl group is bonded but no further carbon atoms

This HTS category, 2931.59.00.60, specifically classifies organo-phosphorous compounds where the phosphorus atom is bonded to exactly one methyl, ethyl, n-propyl, or isopropyl group, and no other carbon-containing groups are directly attached to the phosphorus. This precise structural requirement distinguishes it from other halogenated organo-phosphorous derivatives. The focus is on simple alkyl substituents directly linked to the phosphorus atom, excluding more complex organic structures.

Unlike sibling categories that may cover phosphonofluoridates, phosphonyl difluorides, or specific phosphonochloridates, this classification is for compounds with a simpler organo-phosphorous linkage. For instance, while siblings might involve fluorine or chlorine atoms directly bonded to phosphorus, or more elaborate alkyl chains, the defining feature here is the presence of *only one* of the specified short alkyl groups (methyl, ethyl, n-propyl, or isopropyl) attached to the phosphorus, with no further carbon atoms on that specific substituent.

As this is a leaf node in the HTS classification, there are no further subdivisions. Therefore, the classification is solely determined by the presence of the single specified alkyl group attached to the phosphorus atom, alongside other non-carbon elements or groups, and the absence of any other carbon atoms directly bonded to the phosphorus. Examples might include methylphosphonous dichloride (if it fits the no *further* carbon atoms rule) or similar simple organophosphorous structures with the defined minimal alkyl substitution.