For researchers with an interest in chemical structures, finding structural
information in patents can be difficult. For example, most structures are expressed
in patents in Markush format. Markush structures are essentially structures
involving R-groups, where a part of the molecule is defined by a series of alternatives.
Patent applications frequently include long lists of these alternatives, enabling
the inventor to protect an entire class of compounds rather than just the individual
one they plan to develop. So just one Markush structure in a patent could actually
protect several hundred structures.
To help overcome this problem, Derwent includes the key structure or structures
from a patent in our abstracts, and indexes polymers and chemical structures.
All possible chemical permutations covered by the patent, whether "real" or
"prophetic", are separated into appropriate chemical fragments, which are then
translated into chemical codes.
The hierarchical structure of our indexing allows both specific and generic
searching of chemical compounds. This is an important tool for searchers because
it is the only indexing system available for comprehensive searching of compounds
in chemical patents, enabling searchers to find highly relevant patents that
would not be found in a text-based search.
Application
We apply our indexing to chemicals from patents including rubbers and plastics,
pharmaceuticals, agrochemicals and other chemical compounds.
The indexing is initially assigned to online records that have a basic application
from a major patent-issuing authority, and for which an abstract is published.
Basics from other authorities and certain Japanese documents, which do not have
abstracts, do not have the coding applied until the first appearance of an equivalent
from one of the major patent-issuing authorities.
Example
A simple example of the power of Derwent's chemical indexing to enhance patent
searches is shown here:
Consider you were interested in a particular kind of new catalyst which one
company decided to call "single site catalysts" in their patent applications.
Others may refer to the same structures as "constrained geometry catalysts",
while others may call them "metallocenes".
If you multiply these variations in terminology with the number of languages
and patent offices the patents might be filed in, your search could get very
complicated.
To do the same search on Derwent's patent information you simply need to
search using two Polymer Indexing Codes: (D62 AND C033)
Indexing Ring Systems
Patents sometimes mention general types of rings rather than specifying the
exact ring system involved in an invention e.g. "aryl" or "aromatic heterocyclic
ring system". To enable more specific searches on ring systems, Derwent began
assigning ring numbers from The Ring Index (Patterson, Capell and Walker,
2nd edition, American Chemical Society) to patent indexing records in 1972.
These Ring Index Numbers are five digit numbers that appear in the RR
field of the Derwent World Patents Index database. RINs indicate the
skeleton of ring atoms present, not taking into account substituents, tautomeric
forms, or degrees of unsaturation. You can read more about these numbers in
our Chemical Indexing User Guide.
Derwent Chemistry Resource
The Derwent Chemistry Resource was introduced online (on STN) in 1999
as a chemical structure database for searching specific compounds which have
been indexed in ongoing Derwent World Patents Index (Derwent WPI)
records. Derwent Chemistry Resource is searchable by chemical structure,
and enables simple access to the Derwent WPI bibliographic database by
both specialist and non-specialist chemical searchers alike. Derwent Chemistry
Resource Numbers, which are unique identifiers for specific chemical compounds,
form the link between the Derwent Chemistry Resource database and corresponding
bibliographic indexing in Derwent WPI. The Derwent Chemistry Resource
runs in parallel to, and to a certain extent replicates, current Derwent Subscriber
Chemical Indexing (Fragmentation Codes) for all patents classified in CPI Sections
B, C and/or E.
Merged Markush Service
In 1998, Derwent and the French Patent Office (INPI) combined their separate
Markush files into the Merged Markush Service, managed
by INPI. This single database incorporates the added-value chemical patent structure
indexing produced by Derwent and INPI (originally separately available in WPIM
and MPHARM), providing a searchable patent information resource for the pharmaceutical
and chemical industry.
Markush TOPFRAG
Derwent Markush TOPFRAG is an essential
tool for searching the chemical structures and structure information found in
Derwent's online databases. You can use it to draw structures quickly and easily
offline, before you start accruing online costs, and to generate automatically
search strategies for structure information in Derwent World Patents Index,
and for chemical structures in the Merged Markush Service.
