MPEP § 2121.02 — Compounds and Compositions — What Constitutes Enabling Prior Art (Annotated Rules)

§2121.02 Compounds and Compositions — What Constitutes Enabling Prior Art

USPTO MPEP version: BlueIron's Update: 2026-01-10

This page consolidates and annotates all enforceable requirements under MPEP § 2121.02, including statutory authority, regulatory rules, examiner guidance, and practice notes. It is provided as guidance, with links to the ground truth sources. This is information only, it is not legal advice.

Compounds and Compositions — What Constitutes Enabling Prior Art

This section addresses Compounds and Compositions — What Constitutes Enabling Prior Art. Primary authority: 35 U.S.C. 102 and 35 U.S.C. 102(b). Contains: 1 permission and 12 other statements.

Key Rules

Topic

Assignee as Applicant Signature

7 rules
StatutoryInformativeAlways
[mpep-2121-02-0a1e6d652368b16f9b7abb85]
Affidavit Showing Publication Did Not Synthesize Compound Is Insufficient
Note:
An affidavit stating the publication authors did not synthesize the compound is insufficient to overcome a prior art rejection based on disclosed structure alone.

When a prior art reference merely discloses the structure of the claimed compound, evidence showing that attempts to prepare that compound were unsuccessful before the relevant time will be adequate to show inoperability. In re Wiggins, 488 F.2d 538, 179 USPQ 421 (CCPA 1973). However, the fact that an author of a publication did not attempt to make the compound disclosed, without more, will not overcome a rejection based on that publication. In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985) (In this case, the examiner had made a rejection under pre-AIA 35 U.S.C. 102(b) over a publication, which disclosed the claimed compound, in combination with two patents teaching a general process of making the particular class of compounds. The applicant submitted an affidavit stating that the authors of the publication had not actually synthesized the compound. The court held that the fact that the publication’s author did not synthesize the disclosed compound was immaterial to the question of reference operability. The patents were evidence that synthesis methods were well known. The court distinguished Wiggins, in which a very similar rejection was reversed. In Wiggins, attempts to make the compounds using the prior art methods were all unsuccessful.). Compare In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968) (A claim to a compound was rejected over a patent to De Boer which disclosed compounds similar in structure to those claimed (obvious homologs) and a process of making these compounds. Applicant responded with an affidavit by an expert named Wiley which stated that there was no indication in the De Boer patent that the process disclosed in De Boer could be used to produce the claimed compound and that he did not believe that the process disclosed in De Boer could be adapted to the production of the claimed compound. The court held that the facts stated in this affidavit were legally sufficient to overcome the rejection and that applicant need not show that all known processes are incapable of producing the claimed compound for this showing would be practically impossible.).

Jump to MPEP SourceAssignee as Applicant SignatureApplicant and Assignee Filing Under AIAAIA vs Pre-AIA Practice
StatutoryInformativeAlways
[mpep-2121-02-decd387eeb7451096af60133]
Author Did Not Synthesize Compound Is Irrelevant to Reference Operability
Note:
The fact that a publication’s author did not synthesize the disclosed compound is immaterial when determining reference operability, as long as other evidence shows the synthesis methods are well known.

When a prior art reference merely discloses the structure of the claimed compound, evidence showing that attempts to prepare that compound were unsuccessful before the relevant time will be adequate to show inoperability. In re Wiggins, 488 F.2d 538, 179 USPQ 421 (CCPA 1973). However, the fact that an author of a publication did not attempt to make the compound disclosed, without more, will not overcome a rejection based on that publication. In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985) (In this case, the examiner had made a rejection under pre-AIA 35 U.S.C. 102(b) over a publication, which disclosed the claimed compound, in combination with two patents teaching a general process of making the particular class of compounds. The applicant submitted an affidavit stating that the authors of the publication had not actually synthesized the compound. The court held that the fact that the publication’s author did not synthesize the disclosed compound was immaterial to the question of reference operability. The patents were evidence that synthesis methods were well known. The court distinguished Wiggins, in which a very similar rejection was reversed. In Wiggins, attempts to make the compounds using the prior art methods were all unsuccessful.). Compare In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968) (A claim to a compound was rejected over a patent to De Boer which disclosed compounds similar in structure to those claimed (obvious homologs) and a process of making these compounds. Applicant responded with an affidavit by an expert named Wiley which stated that there was no indication in the De Boer patent that the process disclosed in De Boer could be used to produce the claimed compound and that he did not believe that the process disclosed in De Boer could be adapted to the production of the claimed compound. The court held that the facts stated in this affidavit were legally sufficient to overcome the rejection and that applicant need not show that all known processes are incapable of producing the claimed compound for this showing would be practically impossible.).

Jump to MPEP SourceAssignee as Applicant SignatureApplicant and Assignee Filing Under AIAAIA vs Pre-AIA Practice
StatutoryInformativeAlways
[mpep-2121-02-93e5531f88d187f6c99e04bd]
Patents Show Synthesis Methods Were Well Known
Note:
Evidence of patents shows that synthesis methods for the claimed compound were well known, overcoming a rejection based on prior art that merely discloses the compound's structure.

When a prior art reference merely discloses the structure of the claimed compound, evidence showing that attempts to prepare that compound were unsuccessful before the relevant time will be adequate to show inoperability. In re Wiggins, 488 F.2d 538, 179 USPQ 421 (CCPA 1973). However, the fact that an author of a publication did not attempt to make the compound disclosed, without more, will not overcome a rejection based on that publication. In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985) (In this case, the examiner had made a rejection under pre-AIA 35 U.S.C. 102(b) over a publication, which disclosed the claimed compound, in combination with two patents teaching a general process of making the particular class of compounds. The applicant submitted an affidavit stating that the authors of the publication had not actually synthesized the compound. The court held that the fact that the publication’s author did not synthesize the disclosed compound was immaterial to the question of reference operability. The patents were evidence that synthesis methods were well known. The court distinguished Wiggins, in which a very similar rejection was reversed. In Wiggins, attempts to make the compounds using the prior art methods were all unsuccessful.). Compare In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968) (A claim to a compound was rejected over a patent to De Boer which disclosed compounds similar in structure to those claimed (obvious homologs) and a process of making these compounds. Applicant responded with an affidavit by an expert named Wiley which stated that there was no indication in the De Boer patent that the process disclosed in De Boer could be used to produce the claimed compound and that he did not believe that the process disclosed in De Boer could be adapted to the production of the claimed compound. The court held that the facts stated in this affidavit were legally sufficient to overcome the rejection and that applicant need not show that all known processes are incapable of producing the claimed compound for this showing would be practically impossible.).

Jump to MPEP SourceAssignee as Applicant SignatureApplicant and Assignee Filing Under AIAAIA vs Pre-AIA Practice
StatutoryInformativeAlways
[mpep-2121-02-b25a1a179fbe7b37185873e3]
Distinguishing Wiggins Rejection
Note:
Evidence showing unsuccessful attempts to prepare a compound before the relevant time can show inoperability, distinguishing from Wiggins where such evidence was insufficient.

When a prior art reference merely discloses the structure of the claimed compound, evidence showing that attempts to prepare that compound were unsuccessful before the relevant time will be adequate to show inoperability. In re Wiggins, 488 F.2d 538, 179 USPQ 421 (CCPA 1973). However, the fact that an author of a publication did not attempt to make the compound disclosed, without more, will not overcome a rejection based on that publication. In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985) (In this case, the examiner had made a rejection under pre-AIA 35 U.S.C. 102(b) over a publication, which disclosed the claimed compound, in combination with two patents teaching a general process of making the particular class of compounds. The applicant submitted an affidavit stating that the authors of the publication had not actually synthesized the compound. The court held that the fact that the publication’s author did not synthesize the disclosed compound was immaterial to the question of reference operability. The patents were evidence that synthesis methods were well known. The court distinguished Wiggins, in which a very similar rejection was reversed. In Wiggins, attempts to make the compounds using the prior art methods were all unsuccessful.). Compare In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968) (A claim to a compound was rejected over a patent to De Boer which disclosed compounds similar in structure to those claimed (obvious homologs) and a process of making these compounds. Applicant responded with an affidavit by an expert named Wiley which stated that there was no indication in the De Boer patent that the process disclosed in De Boer could be used to produce the claimed compound and that he did not believe that the process disclosed in De Boer could be adapted to the production of the claimed compound. The court held that the facts stated in this affidavit were legally sufficient to overcome the rejection and that applicant need not show that all known processes are incapable of producing the claimed compound for this showing would be practically impossible.).

Jump to MPEP SourceAssignee as Applicant SignatureApplicant and Assignee Filing Under AIAAIA vs Pre-AIA Practice
StatutoryInformativeAlways
[mpep-2121-02-4c486665fbeae7454e8d03b6]
Evidence of Unsuccessful Attempts to Make Compound Overcomes Rejection
Note:
If evidence shows attempts to make a claimed compound using prior art methods were unsuccessful, it can overcome a rejection based on that prior art.

When a prior art reference merely discloses the structure of the claimed compound, evidence showing that attempts to prepare that compound were unsuccessful before the relevant time will be adequate to show inoperability. In re Wiggins, 488 F.2d 538, 179 USPQ 421 (CCPA 1973). However, the fact that an author of a publication did not attempt to make the compound disclosed, without more, will not overcome a rejection based on that publication. In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985) (In this case, the examiner had made a rejection under pre-AIA 35 U.S.C. 102(b) over a publication, which disclosed the claimed compound, in combination with two patents teaching a general process of making the particular class of compounds. The applicant submitted an affidavit stating that the authors of the publication had not actually synthesized the compound. The court held that the fact that the publication’s author did not synthesize the disclosed compound was immaterial to the question of reference operability. The patents were evidence that synthesis methods were well known. The court distinguished Wiggins, in which a very similar rejection was reversed. In Wiggins, attempts to make the compounds using the prior art methods were all unsuccessful.). Compare In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968) (A claim to a compound was rejected over a patent to De Boer which disclosed compounds similar in structure to those claimed (obvious homologs) and a process of making these compounds. Applicant responded with an affidavit by an expert named Wiley which stated that there was no indication in the De Boer patent that the process disclosed in De Boer could be used to produce the claimed compound and that he did not believe that the process disclosed in De Boer could be adapted to the production of the claimed compound. The court held that the facts stated in this affidavit were legally sufficient to overcome the rejection and that applicant need not show that all known processes are incapable of producing the claimed compound for this showing would be practically impossible.).

Jump to MPEP SourceAssignee as Applicant SignatureApplicant and Assignee Filing Under AIAAIA vs Pre-AIA Practice
StatutoryInformativeAlways
[mpep-2121-02-1a66bcd0b06bcb78485c24a0]
Affidavit Showing De Boer Process Cannot Produce Claimed Compound
Note:
An expert affidavit stating that the process in De Boer cannot produce the claimed compound is sufficient to show inoperability.

When a prior art reference merely discloses the structure of the claimed compound, evidence showing that attempts to prepare that compound were unsuccessful before the relevant time will be adequate to show inoperability. In re Wiggins, 488 F.2d 538, 179 USPQ 421 (CCPA 1973). However, the fact that an author of a publication did not attempt to make the compound disclosed, without more, will not overcome a rejection based on that publication. In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985) (In this case, the examiner had made a rejection under pre-AIA 35 U.S.C. 102(b) over a publication, which disclosed the claimed compound, in combination with two patents teaching a general process of making the particular class of compounds. The applicant submitted an affidavit stating that the authors of the publication had not actually synthesized the compound. The court held that the fact that the publication’s author did not synthesize the disclosed compound was immaterial to the question of reference operability. The patents were evidence that synthesis methods were well known. The court distinguished Wiggins, in which a very similar rejection was reversed. In Wiggins, attempts to make the compounds using the prior art methods were all unsuccessful.). Compare In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968) (A claim to a compound was rejected over a patent to De Boer which disclosed compounds similar in structure to those claimed (obvious homologs) and a process of making these compounds. Applicant responded with an affidavit by an expert named Wiley which stated that there was no indication in the De Boer patent that the process disclosed in De Boer could be used to produce the claimed compound and that he did not believe that the process disclosed in De Boer could be adapted to the production of the claimed compound. The court held that the facts stated in this affidavit were legally sufficient to overcome the rejection and that applicant need not show that all known processes are incapable of producing the claimed compound for this showing would be practically impossible.).

Jump to MPEP SourceAssignee as Applicant SignatureApplicant and Assignee Filing Under AIAAIA vs Pre-AIA Practice
StatutoryInformativeAlways
[mpep-2121-02-af975ef5ee7c193d298ab1c2]
Affidavit Suffices to Show Inoperability
Note:
An affidavit stating that attempts to prepare the claimed compound were unsuccessful is legally sufficient to show inoperability, even if not all known processes are incapable of producing it.

When a prior art reference merely discloses the structure of the claimed compound, evidence showing that attempts to prepare that compound were unsuccessful before the relevant time will be adequate to show inoperability. In re Wiggins, 488 F.2d 538, 179 USPQ 421 (CCPA 1973). However, the fact that an author of a publication did not attempt to make the compound disclosed, without more, will not overcome a rejection based on that publication. In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985) (In this case, the examiner had made a rejection under pre-AIA 35 U.S.C. 102(b) over a publication, which disclosed the claimed compound, in combination with two patents teaching a general process of making the particular class of compounds. The applicant submitted an affidavit stating that the authors of the publication had not actually synthesized the compound. The court held that the fact that the publication’s author did not synthesize the disclosed compound was immaterial to the question of reference operability. The patents were evidence that synthesis methods were well known. The court distinguished Wiggins, in which a very similar rejection was reversed. In Wiggins, attempts to make the compounds using the prior art methods were all unsuccessful.). Compare In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968) (A claim to a compound was rejected over a patent to De Boer which disclosed compounds similar in structure to those claimed (obvious homologs) and a process of making these compounds. Applicant responded with an affidavit by an expert named Wiley which stated that there was no indication in the De Boer patent that the process disclosed in De Boer could be used to produce the claimed compound and that he did not believe that the process disclosed in De Boer could be adapted to the production of the claimed compound. The court held that the facts stated in this affidavit were legally sufficient to overcome the rejection and that applicant need not show that all known processes are incapable of producing the claimed compound for this showing would be practically impossible.).

Jump to MPEP SourceAssignee as Applicant SignatureApplicant and Assignee Filing Under AIAAIA vs Pre-AIA Practice
Topic

AIA vs Pre-AIA Practice

4 rules
StatutoryInformativeAlways
[mpep-2121-02-0064310ec6619b778026eb7a]
Requirement for AIA and Pre-AIA Practice
Note:
The rule outlines the requirements that must be met under both AIA and pre-AIA practices, including the relevant timeframes for inventions.

[Editor Note: This MPEP section is applicable regardless of whether an application is examined under the AIA or under pre-AIA law. For applications subject to the first inventor to file (FITF) provisions of the AIA, the relevant time is "before the effective filing date of the claimed invention". For applications subject to pre-AIA 35 U.S.C. 102, the relevant time is "at the time of the invention". See MPEP § 2150 et seq. Many of the court decisions discussed in this section involved applications or patents subject to pre-AIA 35 U.S.C. 102. These court decisions may be applicable to applications and patents subject to AIA 35 U.S.C. 102 but the relevant time is before the effective filing date of the claimed invention and not at the time of the invention.]

Jump to MPEP SourceAIA vs Pre-AIA PracticeDetermining Whether Application Is AIA or Pre-AIADetermining AIA vs Pre-AIA Applicability (MPEP 2159)
StatutoryInformativeAlways
[mpep-2121-02-a89108875a1dd9602842f6fc]
Relevant Time for Pre-AIA Inventions
Note:
The relevant time for determining prior art under pre-AIA law is the time of the invention.

[Editor Note: This MPEP section is applicable regardless of whether an application is examined under the AIA or under pre-AIA law. For applications subject to the first inventor to file (FITF) provisions of the AIA, the relevant time is "before the effective filing date of the claimed invention". For applications subject to pre-AIA 35 U.S.C. 102, the relevant time is "at the time of the invention". See MPEP § 2150 et seq. Many of the court decisions discussed in this section involved applications or patents subject to pre-AIA 35 U.S.C. 102. These court decisions may be applicable to applications and patents subject to AIA 35 U.S.C. 102 but the relevant time is before the effective filing date of the claimed invention and not at the time of the invention.]

Jump to MPEP SourceAIA vs Pre-AIA PracticeDetermining Whether Application Is AIA or Pre-AIADetermining AIA vs Pre-AIA Applicability (MPEP 2159)
StatutoryInformativeAlways
[mpep-2121-02-3057c7de24c509cee539db36]
Court Decisions on Pre-AIA Patents
Note:
This section discusses court decisions applicable to pre-AIA patent applications, which may also be relevant for AIA patents before the effective filing date.

[Editor Note: This MPEP section is applicable regardless of whether an application is examined under the AIA or under pre-AIA law. For applications subject to the first inventor to file (FITF) provisions of the AIA, the relevant time is "before the effective filing date of the claimed invention". For applications subject to pre-AIA 35 U.S.C. 102, the relevant time is "at the time of the invention". See MPEP § 2150 et seq. Many of the court decisions discussed in this section involved applications or patents subject to pre-AIA 35 U.S.C. 102. These court decisions may be applicable to applications and patents subject to AIA 35 U.S.C. 102 but the relevant time is before the effective filing date of the claimed invention and not at the time of the invention.]

Jump to MPEP SourceAIA vs Pre-AIA PracticeDetermining Whether Application Is AIA or Pre-AIADetermining AIA vs Pre-AIA Applicability (MPEP 2159)
StatutoryInformativeAlways
[mpep-2121-02-1bd85011b7919e216692a284]
Evidence of Inoperable Compound
Note:
Show that attempts to make the claimed compound were unsuccessful before the relevant time to prove inoperability.

When a prior art reference merely discloses the structure of the claimed compound, evidence showing that attempts to prepare that compound were unsuccessful before the relevant time will be adequate to show inoperability. In re Wiggins, 488 F.2d 538, 179 USPQ 421 (CCPA 1973). However, the fact that an author of a publication did not attempt to make the compound disclosed, without more, will not overcome a rejection based on that publication. In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985) (In this case, the examiner had made a rejection under pre-AIA 35 U.S.C. 102(b) over a publication, which disclosed the claimed compound, in combination with two patents teaching a general process of making the particular class of compounds. The applicant submitted an affidavit stating that the authors of the publication had not actually synthesized the compound. The court held that the fact that the publication’s author did not synthesize the disclosed compound was immaterial to the question of reference operability. The patents were evidence that synthesis methods were well known. The court distinguished Wiggins, in which a very similar rejection was reversed. In Wiggins, attempts to make the compounds using the prior art methods were all unsuccessful.). Compare In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968) (A claim to a compound was rejected over a patent to De Boer which disclosed compounds similar in structure to those claimed (obvious homologs) and a process of making these compounds. Applicant responded with an affidavit by an expert named Wiley which stated that there was no indication in the De Boer patent that the process disclosed in De Boer could be used to produce the claimed compound and that he did not believe that the process disclosed in De Boer could be adapted to the production of the claimed compound. The court held that the facts stated in this affidavit were legally sufficient to overcome the rejection and that applicant need not show that all known processes are incapable of producing the claimed compound for this showing would be practically impossible.).

Jump to MPEP SourceAIA vs Pre-AIA PracticeAssignee as Applicant SignatureApplicant and Assignee Filing Under AIA
Topic

Determining Whether Application Is AIA or Pre-AIA

2 rules
StatutoryInformativeAlways
[mpep-2121-02-0a7ccac660959f1450477a79]
Requirement for Effective Filing Date Before Invention
Note:
The rule requires that applications subject to the first inventor to file provisions of the AIA must demonstrate prior art before the effective filing date of the claimed invention.

[Editor Note: This MPEP section is applicable regardless of whether an application is examined under the AIA or under pre-AIA law. For applications subject to the first inventor to file (FITF) provisions of the AIA, the relevant time is "before the effective filing date of the claimed invention". For applications subject to pre-AIA 35 U.S.C. 102, the relevant time is "at the time of the invention". See MPEP § 2150 et seq. Many of the court decisions discussed in this section involved applications or patents subject to pre-AIA 35 U.S.C. 102. These court decisions may be applicable to applications and patents subject to AIA 35 U.S.C. 102 but the relevant time is before the effective filing date of the claimed invention and not at the time of the invention.]

Jump to MPEP SourceDetermining Whether Application Is AIA or Pre-AIADetermining AIA vs Pre-AIA Applicability (MPEP 2159)AIA vs Pre-AIA Practice
StatutoryPermittedAlways
[mpep-2121-02-ad1efab72bd625c0d0b86d03]
Time of Invention for AIA Patents
Note:
The rule specifies that court decisions applicable to AIA patents should consider the time before the effective filing date, not at the time of invention.

[Editor Note: This MPEP section is applicable regardless of whether an application is examined under the AIA or under pre-AIA law. For applications subject to the first inventor to file (FITF) provisions of the AIA, the relevant time is "before the effective filing date of the claimed invention". For applications subject to pre-AIA 35 U.S.C. 102, the relevant time is "at the time of the invention". See MPEP § 2150 et seq. Many of the court decisions discussed in this section involved applications or patents subject to pre-AIA 35 U.S.C. 102. These court decisions may be applicable to applications and patents subject to AIA 35 U.S.C. 102 but the relevant time is before the effective filing date of the claimed invention and not at the time of the invention.]

Jump to MPEP SourceDetermining Whether Application Is AIA or Pre-AIADetermining AIA vs Pre-AIA Applicability (MPEP 2159)AIA vs Pre-AIA Practice

Citations

Primary topicCitation
AIA vs Pre-AIA Practice
Determining Whether Application Is AIA or Pre-AIA
35 U.S.C. § 102
AIA vs Pre-AIA Practice
Assignee as Applicant Signature
35 U.S.C. § 102(b)
AIA vs Pre-AIA Practice
Determining Whether Application Is AIA or Pre-AIA
MPEP § 2150
AIA vs Pre-AIA Practice
Assignee as Applicant Signature
In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985)
AIA vs Pre-AIA Practice
Assignee as Applicant Signature
In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968)
In re Sasse, 629 F.2d 675, 207 USPQ 107 (CCPA 1980)
AIA vs Pre-AIA Practice
Assignee as Applicant Signature
In re Wiggins, 488 F.2d 538, 179 USPQ 421 (CCPA 1973)

Source Text from USPTO’s MPEP

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BlueIron Last Updated: 2026-01-10