Chemical Patent Searching
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Introduction
There is a large body of chemical information found in patents. In fact, the very first US patent was issued to Samuel Hopkins on July 31, 1790 for "an improvement, not known or used before such discovery, in the making of Pot ash and Pearl ash by a new apparatus and process." Now, the number of US patents is well over 6,000,000.
Patents are covered by Chemical Abstracts, and more than 15 percent of the documents found in CA are for patents. Most patents of interest to chemists cover compositions of matter (new chemical compounds, mixtures, pharmaceuticals) or processes (e.g., synthesis of a drug). Under US law, it is even possible to patent things such as 3-D atomic structures, structural databases, and their uses, which may result from the genomics field. Other types of patents are issued for machines, manufactures, plants, and designs. All types of US patents now receive protection for 20 years, with the exception of design patents (original ornamental designs), which get 14 years. With hundreds of thousand of patents issued annually by various countries, a great deal of effort is necessary to organize patent documents for effective retrieval.
Some abstracting and indexing services ignore the patent literature altogether, whereas others, such as Beilstein, have covered patents only at certain times in their history. Patent coverage ended in Beilstein around 1980; prior to 1970, Beilstein is a good source of chemical patent information. Their coverage improved significantly around 1925. For 1930, about 2000 patents were indexed, and this steadily increased to 5,000 in 1956 and to 15,000 in 1966. Coverage then began to slowly decrease, dropping to about 10,000 patents in 1979.
A few commercial organizations, notably Thomson Derwent (worldwide) and IFI CLAIMS (US), specialize in patent coverage in some or all fields. Patents are part of a group of materials generally referred to as INTELLECTUAL PROPERTY that also includes copyright and trademarks.
What is a Patent
A PATENT is a grant of property rights to an inventor by a government. The inventor gets the exclusive right to use or manufacture an invention for monetary gain or to exclude others from making, using, or selling the invention in the country (or countries) whose government(s) issued the patent(s). To obtain a patent, the inventor must file certain documents, and the invention itself must exhibit the qualities of novelty, utility (usefulness), and invention (unobviousness), defined as follows:
- novelty: The concept that the claims must be totally new. The invention must never have been made public in any way, anywhere, before the date on which the application for a patent is filed. In the U.S. this is determined by the date of invention.
- utility: Having some practical utility; fit for some desirable, practical or commercial purpose.
- invention: The invention must not be obvious to an observer who is "skilled in the art". The concept is that the claims defining an invention in a patent appplication must involve an inventive step if, when compared with what is already known (i.e., PRIOR ART), it would not be obvious to someone skilled in the art.
Patent searching is often undertaken in order to prove novelty, a process known as PRIOR ART SEARCHING. In this case, the older patent literature is quite important. A second type of patent search involves INFRINGEMENT, i.e., trying to determine whether someone else is illegally claiming the rights to an invention that is yours. In this case, the search must be exhaustive, but is limited to the last 20 years or so.
An invention must also be useful. For a chemical, that might mean that it shows a beneficial property, such as a pharmacological effect, or it might be an intermediate that is used in synthesizing a product that has an end use.
Patents for chemical inventions must also meet the criterion of invention (un-obviousness). This means that the invention cannot be obvious to someone who is "skilled in the art," that is, who is an expert in the particular area or technology of the invention.
Patents will not be granted for an invention that has already been publicly revealed. Even a posting on the Web can negate the criterion of novelty. In the US, an inventor cannot file for patent protection if an article is published about the invention more than one year before the filing is made. In other parts of the world the patent would be invalidated on the first day of publication of the article. Much of the information in the patent literature is, in fact, never published in any other format. However, some chemists denigrate patents as information sources since the titles, descriptions, and claims tend to use general, broad terminology, rather than the precise wording typically found in journal articles or other forms of primary scientific literature.
The inventor is the PATENTEE, and the inventor may assign the patent protection rights to another person or company, the ASSIGNEE. The inventor submits the first patent application on a certain date known as the PRIORITY APPLICATION DATE. Under the "Paris Convention for the Protection of Intellectual Property of 1883," the priority date is also considered to be the date a patent application is filed in any country that has signed the Paris Convention (as long as the inventor files the application in the other country within 12 months of the priority date). This results in a PATENT FAMILY of publications related to the invention. Some of these may be patents (perhaps in a language that is easier to read than that of the original), whereas others merely document the invention disclosed by the applicant as of the priority date. Regional patenting bodies, such as the European Patent Office, issue patents for groups of countries, and the Patent Cooperation Treaty permits a single filing to initiate the patenting process in a number of countries. The PCT now provides for filing in over 100 countries. The importance of the priority date becomes very obvious when cases arise where two companies file for the same invention at about the same time. Such was the case when ICI Ltd. filed EP 399731 with a priority date of 23 May 1989, and Merck & Co. filed EP 400974 on 30 May 1989.
Patent searching is complex, and a basic understanding of the patenting process is necessary in order to comprehend the different types of documents involved. Most countries publish patent applications 18 months after filing, and those generally start with the letter "A". In addition, a second patent document may be issued after the patent is granted, designated with the letter "B" in general. WO patent numbers are assigned to applications filed through the Patent Cooperation Treaty.
What is a Patent Specification?
When the inventor applies for a patent, the PATENT SPECIFICATION must be submitted. It is a technical document that contains a description of the invention. A typical patent document will include drawings, background of the invention, a summary and a detailed description of the invention, examples, and one or more CLAIMS that define what is legally covered by the invention.
Most countries allow the inventor to define the legal limits of the patent in the claims in both generic terms and specific terms. For chemical patents, generic inventions usually take the form of a MARKUSH STRUCTURE, a structure that contains one or more structural variables based on a list of stated alternatives. Each compound that could be constructed from the list is covered by the claims. Click here for an example of a very long MARKUSH STRUCTURE.
How Long Does a Patent Last?
In the past there was a great deal of variation of the term of protection afforded by patents in different countries. The members of the World Trade Organization (formerly GATT) have now agreed to recognize patents in all fields of technology for a 20-year period that begins with the priority date. On June 8, 1995, the new term took effect in the US. Prior to that date, US patents were issued for a term of 17 years.
Abstracting and Indexing of Patents: Major Patent Databases
Since patents for a particular invention may appear at different times in a number of countries, abstracting and indexing services generally have adopted the practice of abstracting only the first patent issued, called the BASIC PATENT. Later patents in the patent family are indexed as EQUIVALENT PATENTS. Database producers are not always in agreement when it comes to a definition of basic and equivalent patents. On STN, members of a patent family have a common priority application number and date. Further complicating the patent family situation are the patent types that may result in related patents, namely:
- Division: results from a decision by the patent office that the claims are too broad for a single patent. The application is then split into a parent and divisional applications, each claiming a different invention
- Continuation: results when a second and subsequent applications are filed when the original application is pending
- Continuation-in-Part (CIP): results from a second or subsequent application being filed that includes new material even though the original application is pending.
The U.S. Patent and Tradmark Office offers free databases for searching of patent information published January 1, 1976 onward. Searches can be performed only by text terms (or numeric identifiers for the patents themselves). Search collections include patents (and published patent applications), expired patents, and trademarks.
USPTO provides access to US patents classified according to the US Patent Classification code. Another system is the International Patent Classification code issued by the World Intellectual Property Organization.
INPADOC, the International Patent Documentation Center, covers about 60 country patent offices as well as international patent bodies, such as WIPO and EPO (the European Patent Office). Therefore, the INPADOC database is a major source of patent family data and forms the basis for Chemical Abstracts Service's printed patent indexes, and now the data found in the CA and CAPlus files.
IFI CLAIMS files cover U.S. chemical patents from 1950.
Derwent, now a Thomson Scientific company, is one of the world's largest patent services, covering over 30 countries plus the European Patent Office and Patent Cooperation Treaty countries. The WPI (World Patents Index) database covers pharmaceuticals from 1963 and other categories of chemicals for the periods shown below:
- Pharmaceuticals, 1963-
- Agricultural chemicals, 1965-
- Plastics and polymers, 1966-
- All other chemistry, 1970-
Derwent also has the Derwent Patents Citation Index covering US Examiner's citations from 1984 and EPO and PCT Examiner citations from 1978.
See a sample search of the WPINDEX file and STN's How to Search WPINDEX.
Questel offers Markush structure searching in the WPIM and PHARMSEARCH files. PHARMSEARCH covers US and European pharmaceutical patents from 1984 to the present, and WPIM has all of the Derwent chemical and pharmaceutical patents. The Merged Markush Service is a structure file produced by INPI (the French Patent and Trademark Office) and Derwent that can be searched by generic structure input. MMS includes all of the structures previously available in the MPHARM (Markush PHARMSEARCH) and DWPIM (Derwent World Patents Index Markush) files. MMS also includes all the compounds from the Derwent Chemical Resource (DCR). A new database on Questel is PlusPat, a source of worldwide patent data that extends back into the 19th century. PlusPat merges the European Patent Office (EPO) DOCDB file, (which is the basis for EPO databases - including Esp@cenet), with information from additional Questel databases.
CAS Patent Databases on STN
Chemical Abstracts Service's coverage of patents began with the print CA in 1907. Enhanced coverage of patents was initiated around 1960. In 1999, CAS began to include patent family information in its CAplus file. There are two types of patent family relationships in CAplus.
- Closely related family members: have a simple priority application relationship. These are usually included in a single record in CAplus.
- Extended patent family members: result from complex relationships.
- Multiple, but at least one, common priority applications from different countries
- Relationsips resulting from division, addition, continuation, or continuation-in-part patents
- Additional records may be created by CAS in order to capture any new information that is included in these family members.
Patent coverage is extremely fast in CAplus now, with most chemical patents making it into the database within two days of issue.
STN now has a Markush database in the MARPAT file (1988- ). MARPAT provides access by structure to all the specific and generic substances claimed in patents via Markush structures from 1988 to the present.
USPATFULL has the full text of all patents issued by the USPTO from 1975 (with partial coverage from 1971-74). The US Patent Office began to publish US patent applications on March 15, 2001, so the USPATFULL database now includes those documents. They are distinguished from the granted patents by their kind code, A1. CAS indexes chemical patents in USPATFULL, including CAS Registry Numbers. See the example for the USPATFULL file on STN, which has a thesaurus for the USPTO Manual of Classifications and for the WIPO IPC.
The USPATOLD (U.S. Patents Pre-1976) database includes more than 3.5 million records, namely, the full text of patents issued by the USPTO from 1790 through 1975. These records were created from original U.S. patent documents that were converted into electronic form through an optical character recognition process. Since OCR is not 100% accurate, some records may include misinterpreted characters, or portions of the patent text may be missing. To enhance their retrieval, approximately 500,000 USPATOLD records that are also covered by CAplus were supplemented with CAS data.
Examples of Chemical Patents
Note the increase in the US patent numbers issued during the years covered by the table below.
| Issuing Body | Patent Number | Year | Title |
|---|---|---|---|
| USPO | 2,167,351 | 1939 | Piperidine compounds and a process of preparing them |
| USPO | 2,248,018 | 1941 | 4-Aryl-piperidine-ketones and a process of preparing them |
| USPO | 2,479,295 | 1949 | Process and culture media for producing new penicillins |
| USPO | 2,840,577 | 1958 | 17-Thio derivatives of Estratrien-3-ol and of Estratetraen-3-ol |
| USPO | 3,903,094 | 1975 | Piperidyl glycolates |
| USPO | 4,150,158 | 1979 | Oxadiazindione derivatives useful as insecticides |
| USPO | 4,284,794 | 1981 | Prostaglandin derivatives |
| EPO | 0 274 909 A2 | 1987 | Hydrocarbon oxidations catalyzed by azide- or nitrid-activated metal coordination complexes |
| USPO | 4,900,871 | 1990 | Hydrocarbon oxidations catalyzed by iron coordination complexes containing a halogenated ligand |
| USPO | 5,245,036 | 1993 | Process for the preparation of 4-phenoxyquinoline compounds |
Sample CAPlus Entry for A Chemical Patent (Partial Record)
|
Process for the preparation of 4-phenoxyquinoline compounds useful as fungicides. Robery, Roger L.; Alt, Charles A.; DeAminis, Carl V. (Dow Elanco, USA). U.S. (1993), 4 pp. CODEN: USXXAM US 5245036 A 19930914 Patent written in English. Application: US 92-879488 19920507. CAN 120:30682 AN 1994:30682 CAPLUS Patent Family Information
R: CH, DE, DK, ES, FR, GB, IT, LI, NL
Abstract 4-Phenoxyquinolines I [R1, R2 = H, halo, alkyl, haloalkyl; R3, R4 = H, halo], which are known plant fungicides (no data), are prepd. by etherification of corresponding 4-haloquinolines with phenols HOC6H3R1R2 in the presence of a catalytic amt. of a 4-dialkylaminopyridine. The catalyst accelerates an otherwise sluggish reaction, thereby shortening batch cycle times and effectively enlarging manufg. capacity. Thus, reaction of 0.01 mol 4,7-dichloroquinoline with 0.014 mol 2-CF3C6H4OH in refluxing xylene contg. 0.0015 mol 4-dimethylaminopyridine showed complete conversion after 24 h. Isolation of the product via formation, filtration, and neutralization of the HCl salt, gave 89% I (R1 = 2-CF3, R2 = R4 = H, R3 = 7-Cl). Two addnl. I were similarly prepd. in 86-93% yield and reaction times of 16-18.5 h. Also used as catalysts were 4-pyrrolidinopyridine and polyDMAP (polymer-bound 4-aminopyridine from Reilly Industries, Inc.). |
(Reproduced with permission of CAS, a division of the American Chemical Society.)
Miscellaneous
Derwent Fragment Codes offer a way to conduct chemical searches on the Derwent files, such as WPI. Millions of patents were not indexed for searching by structure using graphic input, so the codes developed by Derwent need to be used. In the World Patents Index, these codes serve as links for all patents in appropriate subject areas as far back as 1963 for pharmaceutical patents. As noted above, WPI also has a Markush searching capability for more recent patents in the pharmaceutical, agrochemical, and chemical subject sections. They also have a polymer coding system covering 1966 onward.
The IFI Comprehensive Index and the IFI Uniterm Index provide a type of chemical substructure search capability for US patents to at least 1964. The American Petroleum Institute databases, APIPAT and APILIT, utilize a system of very broad fragmentation codes to index patents and technical literature, respectively. Coverage is not limited to petroleum, but extends to a wide range of petrochemicals, such as hydrocarbons and oxygenates. The files were purchased by Elsevier in 1999 through its Engineering Index division. They are now available on STN as ENCOMPPAT and ENCOMPLIT, as are the IFI files.
Since patent rights can be assigned, it is sometimes difficult to determine who owns the rights to an invention. The USPTO keeps track of patent assignees, but new owners are not required to notify anyone when an invention has changed hands. There is an IFI CLAIMS/Reassignments file. In addition, there are databases that keep track of legal challenges to a patent, but those simply report the fact of the challenge. Legal databases, e.g., Lexis-Nexis or WestLaw, can be consulted for the outcomes of such challenges.
To obtain a copy of a US patent (and other patents) in pdf format, try: esp@cenet.
To obtain a pdf copy of a US patent, go to pat2pdf.org.
Link to Internet Sources for Chemical Patent Searching
This wiki page was originally created by Gary Wiggins. If you have a legitimate desire to contribute to its contents, please request an account from the sysop, Dr. David J. Wild, by e-mailing him at djwild @ indiana.edu
