Note(s)

• In section C, the definitions of groups of chemical elements are as follows:
  • Alkali metals: Li, Na, K, Rb, Cs, Fr
  • Alkaline earth metals: Ca, Sr, Ba, Ra
  • Lanthanides: elements with atomic numbers 57 to 71 inclusive
  • Rare earths: Sc, Y, Lanthanides
  • Actinides: elements with atomic numbers 89 to 103 inclusive
  • Refractory metals: Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W
  • Halogens: F, Cl, Br, I, At
  • Noble gases: He, Ne, Ar, Kr, Xe, Rn
  • Platinum group: Os, Ir, Pt, Ru, Rh, Pd
  • Noble metals: Ag, Au, Platinum group
  • Light metals: alkali metals, alkaline earth metals, Be, Al, Mg
  • Heavy metals: metals other than light metals
  • Iron group: Fe, Co, Ni
  • Non-metals: H, B, C, Si, N, P, O, S, Se, Te, noble gases, halogens
  • Metals: elements other than non-metals
  • Transition elements: elements with atomic numbers 21 to 30 inclusive, 39 to 48 inclusive, 57 to 80 inclusive, 89 upwards
• Section C covers :
  • pure chemistry, which covers inorganic compounds, organic compounds, macromolecular compounds, and their methods of preparation;
  • applied chemistry, which covers compositions containing the above compounds, such as: glass, ceramics, fertilisers, plastics compositions, paints, products of the petroleum industry. It also covers certain compositions on account of their having particular properties rendering them suitable for certain purposes, as in the case of explosives, dyestuffs, adhesives, lubricants, and detergents;
  • certain marginal industries, such as the manufacture of coke and of solid or gaseous fuels, the production and refining of oils, fats and waxes, the fermentation industry (e.g., brewing and wine-making), the sugar industry;
  • certain operations or treatments, which are either purely mechanical, e.g., the mechanical treatment of leather and skins, or partly mechanical, e.g., the treatment of water or the prevention of corrosion in general;
  • metallurgy, ferrous or non-ferrous alloys.
• In all sections of the IPC, in the absence of an indication to the contrary, the Periodic System of chemical elements referred to is the one with 8 groups as represented in the table below. For example, group C07F 3/00 "Compounds containing elements of the 2nd Group of the Periodic System" refers to the elements of columns IIa and IIb.
  • 
• • In the case of operations, treatments, products or articles having both a chemical and a non-chemical part or aspect, the general rule is that the chemical part or aspect is covered by section C.
  • In some of these cases, the chemical part or aspect brings with it a non-chemical one, even though purely mechanical, because this latter aspect either is essential to the operation or treatment or constitutes an important element thereof. It has seemed, in fact, more logical not to dissociate the different parts or aspects of a coherent whole. This is the case for applied chemistry and for the industries, operations and treatments mentioned in Notes (1)(c), (d) and (e). For example, furnaces peculiar to the manufacture of glass are covered by class C03 and not by class F27.
  • There are, however, some exceptions in which the mechanical (or non-chemical) aspect carries with it the chemical aspect, for example:
    • Certain extractive processes, in subclass A61K;
    • The chemical purification of air, in subclass A61L;
    • Chemical methods of fire-fighting, in subclass A62D;
    • Chemical processes and apparatus, in class B01;
    • Impregnation of wood, in subclass B27K;
    • Chemical methods of analysis or testing, in subclass G01N;
    • Photographic materials and processes, in class G03, and, generally, the chemical treatment of textiles and the production of cellulose or paper, in section D.
  • In still other cases, the pure chemical aspect is covered by section C and the applied chemical aspect by another section, such as A, B or F, e.g., the use of a substance or composition for:
    • treatment of plants or animals, covered by subclass A01N;
    • foodstuffs, covered by class A23;
    • ammunition or explosives, covered by class F42.
  • When the chemical and mechanical aspects are so closely interlocked that a neat and simple division is not possible, or when certain mechanical processes follow as a natural or logical continuation of a chemical treatment, section C may cover, in addition to the chemical aspect, a part only of the mechanical aspect, e.g., after-treatment of artificial stone, covered by class C04. In this latter case, a note or a reference is usually given to make the position clear, even if sometimes the division is rather arbitrary.

Note(s)

• In this class, the following term is used with the meaning indicated:
  • "preparation" covers purification, separation, stabilisation or use of additives, unless a separate place is provided therefor.
• Biocidal, pest repellant, pest attractant or plant growth regulatory activity of compounds or preparations is further classified in subclass A01P.
• In subclasses C07C-C07K and within each of theses subclasses, in the absence of an indication to the contrary, and with the exception referred to below, a compound is classified in the last appropriate place. For example, 2-butyl-pyridine, which contains an acyclic chain and a heterocyclic ring, is classified only as a heterocyclic compound, in subclass C07D. In general, and in the absence of an indication to the contrary (such as groups C07C 59/58, C07C 59/70), the terms "acyclic" and "aliphatic" are used to describe compounds in which there is no ring; and, if a ring were present, the compound would be taken by the "last place" rule to a later group for cycloaliphatic or aromatic compounds, if such a group exists. Where a compound or an entire group of compounds exists in tautomeric forms, it is classified as though existing in the form which is classified last in the system, unless the other form is specifically mentioned earlier in the system.
• Chemical compounds and their preparation are classified in the groups for the type of compound prepared. The processes of preparation are also classified in places for the types of reaction employed, if of interest. Examples of such places outside this class are:

  C12P	Fermentation or enzyme-using processes to synthesise a desired chemical compound or composition or to separate optical isomers from a racemic mixture
  C25B 3/00	Electrolytic production of organic compounds
  C25B 7/00	Electrophoretic production of compounds

• General processes for the preparation of a class of compounds falling into more than one main group are classified in the groups for the processes employed, when such groups exist. The compounds prepared are also classified in the groups for the types of compound prepared, if of interest.
• In this class, in the absence of an indication to the contrary, the compounds containing carboxyl or thiocarboxyl groups are classified as the relevant carboxylic or thiocarboxylic acids, unless the "last place rule" (see Note (3), above) dictates otherwise; a carboxyl group being a carbon atom having three bonds, and no more than three, to hetero atoms, other than nitrogen atoms of nitro or nitroso groups, with at least one multiple bond to the same hetero atom and a thiocarboxyl group being a carboxyl group having at least one bond to a sulfur atom, e.g. amides or nitriles of carboxylic acids, are classified with the corresponding acids.
• Salts of a compound, unless specifically provided for, are classified as that compound, e.g. aniline hydrochloride is classified as containing carbon, hydrogen and nitrogen only (in group C07C 211/46), sodium malonate is classified as malonic acid (in C07C 55/08), and a mercaptide is classified as the mercaptan. Metal chelates are dealt with in the same way. Similarly, metal alcoholates and metal phenates are classified in subclass C07C and not in subclass C07F, the alcoholates in groups C07C 31/28-C07C 31/32 and the phenates as the corresponding phenols in group C07C 39/235 or C07C 39/44. Salts, adducts or complexes formed between two or more organic compounds are classified according to all compounds forming the salts, adducts or complexes.

Note(s)

• In this subclass, the following terms or expressions are used with the meanings indicated:
  • "bridged" means the presence of at least one fusion other than ortho, peri or spiro;
  • two rings are "condensed" if they share at least one ring member, i.e. "spiro" and "bridged" are considered as condensed;
  • "condensed ring system" is a ring system in which all rings are condensed among themselves;
  • "number of rings" in a condensed ring system equals the number of scissions necessary to convert the ring system into one acyclic chain;
  • "quinones" are compounds derived from compounds containing a six-membered aromatic ring or a system comprising six-membered aromatic rings (which system may be condensed or not condensed) by replacing two or four CH groups of the six-membered aromatic rings by C=O groups, and by removing one or two carbon-to-carbon double bonds, respectively, and rearranging the remaining carbon-to-carbon double bonds to give a ring or ring system with alternating double bonds, including the carbon-to-oxygen bonds; this means that acenaphthenequinone or camphorquinone are not considered as quinones.
• Attention is drawn to Note (3) after class C07, which defines the last place priority rule applied in the range of subclasses C07C-C07K and within these subclasses.
• Therapeutic activity of compounds is further classified in subclass A61P.
• When classifying in this subclass, classification is also made in group B01D 15/08insofar as subject matter of general interest relating to chromatography is concerned.
• In this subclass, in the absence of an indication to the contrary, a process is classified in the last appropriate place.
• In this subclass, in the absence of an indication to the contrary, "quaternary ammonium compounds" are classified with the corresponding "non-quaternised nitrogen compounds".
• For the classification of compounds in groups C07C 1/00-C07C 71/00and C07C 401/00-C07C 409/00:
  • a compound is classified considering the molecule as a whole (rule of the "whole molecule approach");
  • a compound is considered to be saturated if it does not contain carbon atoms bound to each other by multiple bonds;
  • a compound is considered to be unsaturated if it contains carbon atoms bound to each other by multiple bonds, which includes a six-membered aromatic ring,

  unless otherwise specified or implicitly derivable from the subdivision, as in group C07C 69/00, e.g. C07C 69/712.

• For the classification of compounds in groups C07C 201/00-C07C 395/00, i.e. after the functional group has been determined according to the "last place rule", a compound is classified according to the following principles:
  • compounds are classified in accordance with the nature of the carbon atom to which the functional group is attached;
  • a carbon skeleton is a carbon atom, other than a carbon atom of a carboxyl group, or a chain of carbon atoms bound to each other; a carbon skeleton is considered to be terminated by every bond to an element other than carbon or to a carbon atom of a carboxyl group;
  • when the molecule contains several functional groups, only functional groups linked to the same carbon skeleton as the one first determined are considered;
  • a carbon skeleton is considered to be saturated if it does not contain carbon atoms bound to each other by multiple bonds;
  • a carbon skeleton is considered to be unsaturated if it contains carbon atoms bound to each other by multiple bonds, which includes a six-membered aromatic ring.