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The Chief Justice of the United States, the Honorable Warren E. Burger, pursuant to the authority vested in him by Title 28, United States Code, designated and assigned the following: The Honorable Marvin Jones, Senior Judge, United States Court

of Claims, for October 6–7, 1969, inclusive, and for April 8–9, 1970,

inclusive. The Honorable J. Culley Ganey, Senior Judge, United States Court

of Appeals for the Third Circuit, for October 8–9, 1969, inclusive. The Honorable Matthew F. McGuire, Senior Judge, United States

District Court for the District of Columbia, for October 10, 1969. The Honorable Burnita S. Matthews, Senior Judge, United States

District Court for the District of Columbia, for November 3-7, 1969,

inclusive, and for April 6–7, 1970, inclusive. The Honorable Paul P. Rao, Chief Judge, United States Customs

Court for December 1-5, 1969, inclusive. The Honorable Edward J. McManus, Chief Judge, United States

District Court for the Northern District of Iowa, for January 5-9,

1970, inclusive. The Honorable Morgan Ford, Associate Judge, United States Customs

Court, for February 2–6, 1970, inclusive. The Honorable Samuel M. Rosenstein, Associate Judge, United

States Customs Court, for March 2–6, 1970, inclusive. The Honorable Scovel Richardson, Associate Judge, United States

Customs Court, for April 10, 1970. The Honorable Joe J. Fisher, Chief Judge, United States District

Court for the Eastern District of Texas, for May 4-7, 1970, inclusive.




416 F. 2d 1401; 163 USPQ 479


Processes for Obtaining Substantially Pure 4,4'-Dihydroxy-Diphenyl-Propane 2.2, claims 1 and 3 to 8 of application allowed.

United States Court of Customs and Patent Appeals, October 30, 1969

Appeal from Patent Office, Serial No. 283,088 [Reversed.]

Alvin Sinderbrand, attorney of record, for appellant. James H. Littlepage, Littlpage & Quaintance, of counsel.

Joseph Schimmel for the Commissioner of Patents. Jack E. Armore, of counsel.

(Oral argument October 9, 1969 by Mr. Sinderbrand and Mr. Armore)

Before Rich, ALMOND, BALDWIN, LANE, Associate Judges, and GANEY, Judge,

sitting by designation. ALMOND, Judge, delivered the opinion of the court:

This is an appeal from the decision of the Patent Office Board of Appeals, adhered to on reconsideration, affirmining the rejection of claims 1 and 3 to 8, inclusive, of appellant's application entitled “Processes for Obtaining Substantially Pure 4,4'-Dihydroxy-Diphenyl-Propane 2.2." 1 No claims have been allowed.

The invention relates to an improved process for obtaining substantially pure diphenylol propane (4,4'-dihydroxy-diphenyl-propane 2.2), hereinafter DPP, from the product of the condensation reaction of phenol with acetone in the presence of an acid catalyst. Generally, the DPP thus obtained in the condensation reaction product is in the form of very fine crystals, which causes difficulty in effecting the separation of the solid product from the mother liquid by either filtering or centrifuging. Prior attempts to obtain substantially pure DPP,

1 Serial No. 283,088 filed May 24, 1963.


including the manufacture of DPP in the presence of inert liquid diluents such as liquid hydrocarbons or halogenated hydrocarbons or the recrystallization of DPP out of an organic solvent such as toluene or xylene following heating of the crude condensation product with water in the presence of a base, are said to suffer from economical drawbacks due to requirements of large amounts of acid or solvent as well as from the danger of decomposition of the DPP during recrystallization if the starting product is not acid free.

The present invention allegedly obviates the disadvantages mentioned above and results in a product of greatly improved color and purity. More specifically, this is accomplished by adding either to the crude condensation product or to the condensation reactants suitable amounts of additional water and a water-immiscible organic solvent or diluent, heating the mixture to a temperature below the boiling point thereof to form a wholly liquid system having present an organic phase containing at least 20 percent by weight of DPP, and cooling the system below the crystallization point thereof so that pure DPP crystallizes from the organic phase. The solubility of DPP in the diluent or solvent preferably should be poor while the diluent should provide a mixture with DPP and water that is fully liquid upon heating to a temperature that lies beneath the boiling point of the mixture.

Claims 1 and 8 are illustrative:

1. In the process for producing diphenylol propane (DPP) by the condensation reaction of phenol with acetone in the presence of an acid catalyst, the steps for obtaining substantially pure diphenylol propane comprising:

heating a mixture consisting essentially of the acid containing reaction product, water in an amount between 10% and 1000%, by weight, of the amount of diphenylol propane in said reaction product, and a water immiscible organic solvent in an amount between 10% and 400%, by weight, of said amount of diphenylol propane, said mixture being heated to a temperature between 70° C. and 100° C. which is below the boiling point thereof, and said organic solvent being selected from the group consisting of toluene, xylene, monochlorobenzene, 1-1-2-2-tetrachloroethane and 1-2-dichloroethane to form, with said diphenylol propane and water in said relative amounts, a system which is wholly liquid at said temperature and which includes at least a first organic phase containing said solvent, at least 20% of diphenylol propane and a minor part of water, and a second aqueous, acid-containing phase;

cooling below the crystallization point of said system, thereby to cause substantially pure diphenylol propane to crystallize therefrom; and

collecting the crystallized pure diphenylol propane. 8. The process as in claim 1;

wherein said organic solvent is added to the condensation reactants so that the condensation reaction occurs in the presence of said organic solvent, and said water is added upon the completion of the condensation reaction.

Claims 3 to 7, inclusive, are dependent on claim 1 and the limitations added by such claims are not in issuc, the parties having agreed that consideration of representative claim 1 will be dispositive of claims 1 and 3 to 7.

The appealed claims were rejected as being unpatentable under 35 U.S.C. 103. The references relied upon are: Grimme et al. (Grimme)----

2,959,622 November 8, 1960 Stanley et al. (Stanley-Great Britain)-

557,976 December 14, 1943 Grimme discloses a process for purifying DPP whereby the condensation reaction product, crude DPP, is washed to remove therefrom the acid condensation agent and then neutralized with a compound having an alkaline reaction. The crude neutralized product is then dissolved while hot in an organic water-immiscible solvent such as ethylene dichloride or monochlorobenzene. After completion of the dissolving process, there forms an aqueous layer and an organic layer containing the DPP and unreacted phenol. After separation, the organic phase is cooled to precipitate out DPP which, after washing, is a practically colorless homogenous crystalline product. The quantity of the solvent used is variable, but at least such a large quantity is to be used as will completely dissolve the DPP.

Stanley discloses that the condensation reaction of phenol with acetone to produce DPP may be advantageously carried out in the presence of a solvent such as dichloroethylene or chlorobenzene.

а The examiner rejected claims 1 and 3–7 as unpatentable over Grimme under 35 U.S.C. 103. While noting that the amount of water-immiscible organic solvent employed by Grimme is 500% or more of the crude DPP to be purified, he reasoned that "it is within the expected skill of the art to determine optimum proportions for the purpose of achieving better results."

Claim 8 was rejected as unpatentable over Grimme in view of Stanley under 35 U.S.C. 103 since the examiner considered it obvious to add the organic solvent to the reactants prior to the production of DPP.

The board affirmed the rejections, stating as to claims 1 and 3–7:

It is a common, routine expedient in operating industrial processes to use the minimum practical amount of materials. We consider that it would be obvious to those of average skill in the art to determine the practical minimum proportion of organic solvent in the examples of the reference. It appears that such minimum will be materially lower than the figures suggested by the table in column 3 of the reference, but this alone does not, in our opinion, provide a basis for patentability. We do not find that the reference requires an amount of solvent at least equal to the solubility at the boiling point in the table in column 3. We believe that workers in the art would recognize that solubility values obtained with pure two component systems (as in the table) are rarely the same as for the same system with impurities and a third component added, viz, water in the present case. Appellant states that he “has found that, in the presence of water the amount of solvent required to produce a wholly liquid with DPP is far less than the amount of solvent required to dissolve the DPP therein, as disclosed by Grimme

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