Why it is now easier to patent high-purity chemicals at the EPO, and how to do it

Why it is now easier to patent high-purity chemicals at the EPO, and how to do it

Making the initial discovery of a new and potentially useful compound is just the first stage in a long road to market for a new commercial product. In addition to the challenges of obtaining regulatory approval for a new compound, it can take years to develop ways to manufacture the new compound on a scale and at the purity required for it to become commercially viable. This development process can lead to new innovations, offering a chance to file new patent applications that extend the life of IP protection for the new product.
The European Patent Office (EPO) recently changed the way it decides whether applications to high-purity chemicals are patentable. This could impact industries such as pharma, food & beverage and cosmetics where it can be crucial that chemical products have high purity. 

Purity at the EPO is now simplified

For the past twenty years or so, the EPO has taken a critical view of applications that claim known compounds at a higher degree of purity – particularly in organic chemistry, where they have long considered “it is common practice for a person skilled in the art of preparative organic chemistry to (further) purify a compound obtained in a particular chemical manufacturing process according to prevailing needs and requirements” (decision T 990/96).
Although this position acknowledges what chemists know to be true in some instances (purification of a known compound can be a routine activity), it meant patent applications claiming a compound at a high degree of purity were often found to lack novelty over prior art that described the same compound at any purity. In effect, it was almost impossible to claim a high-purity chemical at the EPO.
This all changed in early 2019, when a Technical Board of Appeal in T 1085/13 considered an application relating to amorphous lercanidipine hydrochloride, an anti-hypertensive drug that is easier to absorb in its amorphous form. The applicant claimed the amorphous form having a purity of at least 99.5% and containing less than 0.5% of the crystalline form. Examiners had applied the old law and found the claim to lack novelty in view of prior art that disclosed the synthesis of (only) 97.91 % pure lercanidipine hydrochloride. However, the Board decided it was incorrect to assess novelty in this way and set out a new test for assessing the novelty of a claim directed towards compounds of a certain purity:

  1. A claim defining a compound as having a certain purity lacks novelty over a prior-art disclosure describing the same compound only if the prior art discloses the claimed purity at least implicitly, for example by way of a method for preparing said compound, the method inevitably resulting in the purity as claimed. Such a claim, however, does not lack novelty if the disclosure of the prior art needs to be supplemented, for example by suitable (further) purification methods allowing the skilled person to arrive at the claimed purity.

  2. The question of whether such (further) purification methods for the prior-art compound are within the common general knowledge of those skilled in the art and, if applied, would result in the claimed purity, is not relevant to novelty, but is rather a matter to be considered in the assessment of inventive step.

This new approach moves the question of what is “common practice” when purifying a known compound into the assessment of inventive step, which is much closer to the way that claims to high-purity compounds are examined in other jurisdictions. The change also makes it more likely claims to high-purity compounds will be considered allowable by the EPO, particularly in cases where new purification methods had to be painstakingly developed to achieve the desired degree of purity. 

Drafting applications for high-purity chemicals

We have first-hand experience of the new approach in T 1085/13 being applied by examiners at the EPO. A summary of the Board’s decision has also been included in the July 2019 edition of the Case Law of the Boards of Appeal (The White Book). We believe it is now easier to obtain patent protection for high-purity chemicals at the EPO. Here is our guidance on how to take advantage of this change:

1. Quantify rather than qualify
When filing a new patent application to claim a high-purity chemical, use numerical values to describe the amount of impurities in your product, rather than qualitative terms (e.g. try to avoid expressions like “substantially pure” where possible). When doing this is, it is important to describe how the amount of the impurity is measured. 

Also consider including multiple cut-offs for the amount of impurities present. This makes it easier to amend the application to avoid prior art that you might only become aware of during examination.
2. Name the impurities
If one or more of the impurities that occur in a product are particularly difficult to remove, it may be easier to show an inventive step if the residual amount of those impurities is specified in the claim (especially if removing those impurities overcomes a known problem in the prior art).
3. Include comparative data
It can be easier to argue claims to a high-purity chemical are inventive if the application includes experiments showing the high-purity compound cannot be obtained using conventional purification methods.
4. Have a plan B
If it turns out claims to the high-purity chemical are going to be rejected, then process claims could offer an alternative way to obtain patent protection. Patenting a process for making a chemical can be highly valuable in Europe because the protection extends to the product directly obtained from that process. An application claiming a chemical should always include information on how to make it anyway, so consider how best to claim both the product and its manufacturing process – including any formulation steps that incorporate the chemical into the final, commercial product – when preparing a new patent application.



It is now easier than ever before to extend the lifetime of patent protection for high-purity chemical products in Europe. For more information on how to make the most of this chance to extract the maximum value for your chemical innovations, speak to your usual Kilburn & Strode contact.

If you would like to have a word with Dan or Mark to discuss this article, they would love to hear from you.

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