This case is before us on a petition by the party Krenzer to “recall, set aside and vacate” our mandate in appeal No. 9198, decided June 27, 1974.1 The basis for the petition is an alleged fraud on this court and on the Patent and Trademark Office (PTO) Board of Patent Interferences (board) by the respondents Stoffel and Schumacher (Stoffel). Stoffel has requested oral argument. We deny the Krenzer petition; the Stoffel request is thus moot.
Background
To put this petition in perspective, we describe the prior proceedings. Krenzer and Stoffel were parties to an interference (No. 96,419) in which Krenzer was junior party.2 The interference comprised only one count:
A method of destroying undesired vegetation which comprises applying to said *1215vegetation a herbicidally effective amount of a compound of the formula
wherein R is lower alkyl, Y is a member of the group consisting of oxygen and sulfur, each X is independently selected from the group consisting of lower alkyl, lower alkoxy, nitro and halogen, and n is an integer from 0 to 4, inclusive. [Ring position numbers added.]
The compounds defined in the count are 3,5-dioxo-l,2,4-oxadiazolidines and 3-thiono-5-oxo-l,2,4-oxadiazolidines which are substituted at the N-2 nitrogen with phenyl (or substituted phenyl) and at the N-4 nitrogen with lower alkyl.3
The issues before the board were: (1) whether the Stoffel application sufficiently indicated how to make the compounds defined in the count, i. e., whether Stoffel had a “right to make” the count; and (2) whether Krenzer’s priority proofs established an actual reduction to practice prior to Stoffel’s reduction to practice. As to the first issue, Stoffel’s specification stated that the compounds could be prepared “by the reaction of an isocyanate with a hydroxyl amine and ethylchloroformate.” For details, such as reaction scheme, selection of particular reactants, and reaction conditions, Stoffel referred to a publication of Zinner. This publication referred to still other publications of Zinner on which Stoffel also relied.
It was not disputed that the Zinner publications showed how to prepare 3,5-dioxo-l,-2,4-oxadiazolidines (and presumably 3-thiono-5-oxo-l,2,4-oxadiazolidines). The question framed by the board, however, was whether Zinner taught the preparation of “the much narrower group of compounds embraced by the count.” The board decided that question against Stoffel after finding an example in Zinner in which, according to the board, “no ring closure was effected.” Had closure been effected, the end-product would have been 2-phenyl-4-butyl-3,5-dioxo-l,2,4-oxadiazolidine, a compound within the count, and apparently the only compound within the count which Zinner mentions.
Stoffel appealed the board’s decision to this court in appeal No. 9198. We reversed the board and remanded the case for consideration of the priority proofs. Our reading of Zinner had persuaded us that although no ring closure had been effected in the example cited by the board, it was because ring closure had not been attempted. The negative inference drawn by the board, i. e., that Zinner had unsuccessfully tried to make a compound of the count, was therefore without foundation. Other facts also militated against a negative inference. First, Zinner showed the successful preparation of 2-phenyl-4-cyclo-hexyl-3,5-dioxo-1.2.4- oxadiazolidine, a compound very close to those of the count. Second, Stoffel stated in his application that he had successfully prepared 2-phenyl-4-methyl-3,5-dioxo-l,-2.4- oxadiazolidine, a compound within the count, by the Zinner method referred to. Given these teachings, we found that no technical reason was apparent why the example referred to by the board could not be prepared by the same technique. We concluded that Stoffel’s specification and the Zinner publications were sufficient “to enable any person skilled in the art to make the compounds which are employed in the recited method.”
After remand, the board considered the priority proofs and awarded priority to Stoffel. Krenzer’s assignee then filed a civil action under 35 USC 146 against Stoffel’s assignee in the United States District Court for the Northern District of Illinois. Velsicoi Chemical Corp. v. Monsanto Co., Civil Action No. 74 C 3702 (N.D.Ill., filed *1216December 20, 1974). During the course of that proceeding, Velsicol obtained documents and depositions which it alleged showed improper and fraudulent conduct on the part of Stoffel before the board and this court on the “right to make” issue. The District Court refused to permit Velsicol to relitigate the “right to make” issue on the ground of res judicata. The District Court also refused to remand the case to the board to consider the fraud allegations, stating that the case was almost ready for trial and that Velsicol had already filed a petition with the Commissioner of Patents and Trademarks under 37 CFR 1.56 to strike the Stoffel application for fraud. The court stated that a remand would only result in “a duplication of effort before the Commissioner” and that to grant it would “tend to reward the plaintiff’s proliferation of litigation.” Ultimately, the District Court entered an order that Stoffel was entitled to “judgment affirming the decision of the Board of Patent Interferences.”
Meanwhile, Krenzer’s Rule 56 petition was pending before the Commissioner. Instead of ruling on the merits of the petition, the Commissioner issued an interlocutory ruling which states in relevant part:
Inasmuch as Krenzer alleges that a fraud has been committed on the U. S. Court of Customs and Patent Appeals and since the Office should not presume to determine what effect, if any, the acts alleged by Krenzer, if proven, would have had on the proceedings before the Court, further action on the petition is being held in abeyance for a period of one (1) month to permit Krenzer to bring the matter to the attention of the Court in the form [of] a motion to recall its mandate. See Kravig v. Henderson, 393 F.2d 1017, 55 CCPA 1182, 157 USPQ 564 (1968).
Krenzer filed this petition pursuant to the Commissioner’s suggestion.
Petitioner’s Arguments
Krenzer’s petition is based on documents and depositions obtained by Velsicol in the district court action. He alleges that they show that Stoffel improperly or fraudulently withheld information from this court in appeal No. 9198 and from the PTO in the proceedings which led up to that appeal. More particularly, Krenzer alleges:
1. That Stoffel failed to disclose ethyl chloroformate as a critical reactant in the application as originally filed and Cnat such failure was “grossly negligent, deliberate and reckless,” since Stoffel knew that ethyl chloroformate was a necessary reactant when the application was filed. Krenzer admits, as he must, that the application was amended to disclose ethyl chloroformate as a reactant before the declaration of the interference which led to appeal No. 9198.
2. That Stoffel committed fraud in failing to disclose certain unsuccessful experiments. Krenzer points to certain pages of Stoffel’s laboratory notebooks obtained by discovery in the district court action to show that “although Stoffel followed the general method of Zinner by reacting a hydroxylamine, an isocyanate and ethyl chloroformate in attempting to make certain substituted phenyl oxadiazolidines, he met with repeated failures.” Krenzer regards as “especially noteworthy” a notebook entry which he characterizes as an “abortive attempt” to make a 2-substituted phenyl-4-alkyl-3,5-dioxo-l,2,4-oxadiazolidine which he describes as “the prize sought in this whole interference proceeding.”
3. That Stoffel failed to disclose the fact that the substituted phenyl hydroxylamines, starting materials for making compounds of the count, were unstable. Krenzer refers to a Stoffel summary report obtained in discovery in which it is stated that: “All substituted phenyl hydroxylamines, particularly the chloroderivatives, are notoriously unstable.”
OPINION
We hold the allegations of fraud to be without merit. The allegation that Stoffel deliberately failed to disclose ethyl chloroformate as a necessary reactant in the application as originally filed is incredible. We cannot conceive of this applicant deliberately filing an application with a defect *1217so obvious that it would be discovered by the first person who attempted to follow its teachings. Deliberate failure to disclose is inconsistent with the fact that Stoffel did disclose ethyl chloroformate as a necessary reactant by the amendment referred to above.
As to the unsuccessful experiments Krenzer has found in Stoffel’s laboratory notebooks, only one of the compounds which Krenzer alleges Stoffel unsuccessfully tried to make is within the count. Krenzer admits this, but states that Stoffel “argued the applicability of the Zinner disclosures in general,” pointing to the illustration of 23 Zinner compounds in Stoffel’s brief in appeal No. 9198, all of which lie outside the count. It is clear, however, from the remarks prefacing and concluding those illustrations, that Stoffel was merely demonstrating that the substituent of the hydroxylamine reactant goes to the N-2 nitrogen atom of the product of the Zinner reaction, while the substituent of the isocyanate reactant goes to the N-4 nitrogen atom. This demonstration was made to support Stoffel’s argument that: “If one skilled in the art is just given the information of these [Zinner] equations and told to prepare a 2-phenyl-4-alkyl compound [the compounds of the count], he need only select phenyl hydroxylamine and an alkyl isocyanate as the starting materials.” Thus, the argument which Stoffel actually made is quite different from an argument premised on the general operability of the Zinner method for compounds outside the count. Indeed, the latter argument could hardly have been made, since in appeal No. 9198 both Krenzer and Stoffel pointed out where Zinner had failed to make two compounds outside the count.
The single compound within the count which Krenzer charges Stoffel with failing to make is one for which Stoffel was unable to prepare the starting material, a hydroxylamine, and apparently just turned to another experiment. This is quite clear from an examination of the notebook page on which the experiment appears. It can hardly be termed a failure, and Stoffel has pointed to other methods, known to those skilled in the art, by which that starting material could have been prepared. Krenzer does not deny that these methods were available. Stoffel also points out that the same compound was prepared by Krenzer according to the Zinner method. Krenzer can only lamely respond that although the reactants he used to prepare the compound were similar, there is no evidence that he in fact used the Zinner method.
Finally, the Stoffel summary report does not support any withholding of information of the instability of the substituted phenyl hydroxylamines. That report refers to the alleged instability as “notorious,” a clear indication that those skilled in the art were already aware of it.
We have said that proof of fraud must be clear and convincing, imposing on one alleging fraud, “a heavy burden of persuasion.” Norton v. Curtiss, 433 F.2d 779, 57 CCPA 1384, 167 USPQ 532 (1970). The evidence presented here certainly does not meet that standard. It therefore fails as a basis for an equitable defense and it certainly fails when, as here, it is employed as a basis for having this court recall a mandate which has long since been acted on by the Patent and Trademark Office.
PETITION DENIED.
. The opinion was not published.
. Krenzer was involved on the basis of his application serial No. 703,497, filed November 17, 1967, but was accorded the filing date of a parent application, serial No. 535,323, filed March 18, 1966. The Stoffel application, serial No. 513,577, was filed December 13, 1965.
. It is helpful to note that Stoffel claimed many other 3,5-dioxo- (and 3-thiono-5-oxo-) 1,2,4-ox-adiazolidines.