301 F2d 684 Application of William H Schechter
301 F.2d 684
Application of William H. SCHECHTER.
Patent Appeal No. 6770.
United States Court of Customs and Patent Appeals.
May 4, 1962.
Brown, Critchlow, Flick & Peckham, Pittsburgh, Pa. (Fulton B. Flick, Pittsburgh, Pa., of counsel), for appellant.
Clarence W. Moore, Washington, D. C. (Jack E. Armore, Washington, D. C., of counsel), for the Commissioner of Patents.
Before WORLEY, Chief Judge, and RICH and SMITH, Associate Judges.
WORLEY, Chief Judge.
Claims 1 through 3, and 91 in appellant's patent application for a process of producing alkali metal borohydrides were rejected by the Primary Examiner as unpatentable over certain prior art. The Board of Appeals affirmed the rejection. Appellant alleges reversible error in the board's decision.
Claim 1 is representative and reads:
"1. That method of making sodium borohydride comprising finely dispersing hydride of the alkali metal in an inert liquid of high boiling point, maintaining the dispersion at a substantially uniform temperature of about 250 to 350°C, and reacting said sodium hydride with a boron-containing reagent introduced into the dispersion and selected from the group consisting of boron halides and their organic addition agents, boric oxide, alkali metal borohalides, and alkyl borates, and recovering said sodium borohydride from the system."
References relied on by the examiner are:
Schlesinger et al. (I) 2,534,533 December 19, 1950; Schlesinger et al. (II) 2,494,968 January 17, 1950; Muckenfuss 1,958,012 May 8, 1934.
Appellant's invention relates to a process of producing alkali metal borohydrides characterized by the formula MBH4 in which M represents an alkali metal. The process consists of the steps of (1) dispersing the metal hydride in an "inert liquid, most suitably one of high boiling point such as mineral oil," (2) heating the dispersion to between 250° and 350°C and (3) introducing a dry boron-containing reagent while stirring the dispersion rapidly. The specification states:
"Fine dispersion of the metal hydride is a sine qua non of all embodiments of the invention, otherwise the reactions do not proceed, at least at any acceptable rate."
The "boron-containing reagent" is defined as:
"* * * boron halides, such as boron trifluoride (BF3) or boron trichloride (BC13), and the organic addition products of boron halides of which a considerable number are known, as well as alkyl borates, e. g., methyl and ethyl borates: [B (OMe)3; B(OEt)3]. Boron reagent as the term is here used also includes boric oxide (B2O3), or alkali metal borohalide such, for example, as sodium borofluoride (NaBF4), so that such compounds too are boron-containing reagents for present purposes."
Schlesinger et al., patent No. 2,534,533, hereinafter referred to as Schlesinger I, discloses the preparation of alkali metal borohydrides by the reaction of alkali metal hydrides and boron-containing reagents. The method utilized by Schlesinger I is stated as follows:
"* * * The apparatus is flushed out with dry nitrogen, and sodium hydride in powdered form is introduced into the apparatus without contacting it with air and moisture. The sodium hydride is slowly heated to between 200° and 275°C., and the methyl borate is added at such a rate that the theoretical amount is introduced over a period of 40 to 60 minutes. During the adding of the methyl borate the reacting materials are vigorously stirred. After all the borate has been added the temperature is maintained and the stirring is continued until the reaction is complete. * * *"
When boric oxide is used as the boron reagent, operating temperatures of 300-375°C are required. Schlesinger I also discloses the reaction of the boron reagent with an alkali metal and hydrogen to produce the borohydride.
Schlesinger II, patent No. 2,494,968, discloses the preparation of alkali metal alkoxyborohydrides by reacting, in different molecular proportions, the same materials used in Schlesinger I, viz., alkali metal hydrides and boron-containing reagents. The patentees state:
"Generally speaking the reaction is exothermic and tends to occur vigorously. The vigor of the reaction may be at least partially controlled by the use of diluents which serve to prevent the temperature of reaction from reaching an unduly high value. * * *"
The materials named as diluents are benzene, toluene and dioxane. Example IV of the patent teaches placing benzene, the hydride and the borate in the reaction vessel prior to heating.
Muckenfuss teaches the preparation of alkali metal hydrides from the respective alkali metal and hydrogen. Liquid distributing agents, such as commercial lubricating and paraffin oils, are used in the process.
The examiner rejected claims 1 and 9 as unpatentable over Schlesinger I in view of Schlesinger II. Claims 2 and 3 were rejected on the same prior art further in view of Muckenfuss.
The board, in sustaining the examiner, stated:
"The examiner's answer sets forth the examiner's position with commendable thoroughness and clarity. Since we agree with this position as stated, we adopt as a statement of our opinion the examiner's answer, as amplified by the following comments."
Those comments included discussion of a journal article2 cited by appellant. The board further relied on In re Migrdichian, 29 CCPA 110, 129 F.2d 547, for the proposition that
"* * * the indicated use of an inert diluent is a conventional expedient that requires no more than the ordinary skill of the art. * * *"
The examiner's position on claims 1 and 9 is that Schlesinger I teaches the claimed process "except for the limitation that the sodium hydride is dispersed in an inert liquid of high boiling point when it is contacted with the boron containing reagent." He stated that "In view of the close similarity of the reactions taught by Schlesinger et al (I) and (II), no invention can be seen to reside in merely controlling the temperature in the reaction taught by Schlesinger et al (I) in the same manner as taught by Schlesinger et al (II), i. e., by dispersing the sodium hydride in an inert liquid such as benzene or toluene." The limitation of claims 2 and 3 that the liquid be mineral oil was considered by the examiner "to be within the skill of the art", especially in view of Muckenfuss.
Appellant in his brief states "The precise point of novelty lies in maintenance of fine dispersion of the sodium hydride in mineral oil or similar inert high boiling liquid." He contends that the use of such a liquid in the instant process is unobvious, basing his argument on the allegation that the "position of the Patent Office utterly overlooks the history of this field and the relevant facts" as well as the affidavits of record, citing In re McKenna et al., 40 CCPA 937, 203 F.2d 717. He further alleges that the rejection is based on hindsight arising from appellant's disclosure and that the references were improperly combined.
Appellant submitted for the examiner's consideration the affidavit of one Dr. Millard which states that the operation of the process of Schlesinger I "frequently develops" hot spots allegedly caused by the "inadequate dissipation of heat throughout the reaction mixture." The affidavit further states that in appellant's process
"* * * There has been no occurrence of an uncontrolled violent reaction of the type described for the `dry' process. The reason for the more satisfactory control of this reaction when carried out in mineral oil suspension is believed to be due to the more even distribution of heat throughout the reaction mixture and the quick dissipation of heat which precludes the development of a `hot spot'. Another reason for the better control which is obtained when this reaction is carried out in mineral oil suspension is due to the solubility of methyl borate in mineral oil. * *"
We have thoroughly considered all of appellant's contentions but are unable to agree that the board erred as alleged.
As pointed out by the examiner, Schlesinger II clearly teaches the exothermic character of the reactants and the control of that reaction by the use of diluents. Since Schlesinger I teaches a process utilizing the identical reactants, it would be obvious, in our opinion, to also use diluents to control that reaction. It is true that Schlesinger II discloses diluents of relatively low boiling point, such as benzene or toluene.3 However, it is noted that the reaction of Schlesinger II is carried out at about 90°C, as in "Example IV," while Schlesinger I specifically requires a temperature "between 200° and 275°C" for the preparation of the borohydride. If one were to control the Schlesinger I exothermic reaction in the manner taught by Schlesinger II, it is evident that an inert liquid of higher boiling point would be necessary. In our opinion, the use of a high boiling inert diluent in the process of Schlesinger I would be obvious to one skilled in this art in view of the teachings of Schlesinger II.
The decision is affirmed.