United States Patent Office Patented Aug
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3,523,090 United States Patent Office Patented Aug. 4, 1970 2 a “resin acid.” The structure and numbering system of levopimaric acid follows: 3,523,090 POLYURETHANE PLASTIC FROM RESIN ACID DIOLS Bernard A. Parkin, In, Lake City, Fla., Hugh B. Sum mers, Jr., Savannah, Ga., and Glen W. Hedrick, Lake City, Fla., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Original application June 11, 1968, Ser. No. 562,951. Divided and this application Apr. 11, 1968, 10 Ser. No. 738,749 Int. Cl. (109k 3/00; H05b 33/00 US. Cl. 252-482 1 Claim 15 ABSTRACT OF THE DISCLOSURE A saturated diol prepared by the hydrolysis and the 20 subsequent double bond and functional group reduction of the formaldehyde adduct of levopimaric acid. The diol is a useful glycol extender for the production of poly urethane foams and rubbers. 25 / Levopimaric acid (I) A non-exclusive, irrevocable, royalty-free license in the 30 The nomenclature is that of Fieser and Fieser (Nat invention herein described, throughout the world for all ural Products Related to Phenanthrene by Fieser and purpose of the United States Government, with the power Fieser, third edition, 1949, page 40, Published by Rein to grant sublicenses for such purposes, is hereby granted hold Publishing Corporation, New York, N.Y.) to the Government of the United States of America. As noted above, levopimaric acid (I) constitutes about This application is a division of application bearing one-?fth of the total acid content of pine gum. As will Ser. No. 562,951, ?led June 30, 1966. be seen from the chemical structure, it contains double This invention relates to a method for the preparation bonds at the 6-7, 8-8a positions. This conjugated system of diols from pine gum resin acids and to the products so reduces its resistance to the heat required in the distilla produced. rMore speci?cally, it deals with a process for 40 tion of turpentine. Consequently, the residue (rosin) con ?rst forming a formaldehyde-levopirnaric acid adduct (11) tains little, if any, levopirnaric acid. and, subsequently, converting this adduct to 6-(hydroxy It has been observed that upon heating levopimaric acid methyl) abietic acid (?ll), 6-(hydroxymethyl) dihydro (I) with formaldehyde under certain conditions, a hy abietic acid ('IV), 6-(hydroxymethyl) tetrahydroabieti droxy acid was obtained which gave an ultraviolet (U.V.) 1101 (V), 6-hydroxymethyl( abietinol (VI), and to the for 45 absorption spectrum almost identical in form with that maldehyde adduct of abietinol (VII). The 6-hydrnxy of abietic acid, but with a principal maximum at 243 methyl) abietinol (V1) is useful in the preparation of millimicrons instead- of the expected 241 millimicrons. protective coatings and has the air drying capacity of Rearrangement to an abietic-type double-bond system had rosin. The saturated diol (V) may be prepared from the apparently taken place with substitution of a methylol other compounds as intermediates or directly from the 50 group on a carbon of the conjugated double-bond system. adduct (II) in one step. The saturated diol is useful in Substitution of a methylol group on a carbon of the con the preparation of polyurethane foams and rubbers. Most jugated double-bond system of abietic acid should, ac important, when the saturated diol is used as a partial cording to Woodward rules, have given a shift of the replacement for polyethylene glycols and/ or polypropyl U.V. maximum to M6 millimicrons. Such a shift was ob ene glycols in the production of polyurethanes, the re 55 served by E. E. Royals and J. T. Greene (J. Org. Chem, sultant ?lms and coatings have improved hardness, tough 23, 1,437 (1958)) as a result of the Prime reaction on ness, and are clear and colorless. abietic acid. The term “pine gum,” as used in this speci?cation and However, by careful control of the reaction conditions the claims, relates to crude pine gum and particularly to and the conditions of product isolation, We isolated a one of the main components of crude pin gum, levopimar crystalline intermediate which showed no U.V. absorption ic acid, which is present in amounts ranging from about above 210 millimicrons and contained no free hydroxyl 18 to 30 weight percent. Since levopimaric acid is ther group. This product resulting from the Diels-Alder-type mally unstable and is lost in the conversion of pine gum addition of formaldehyde to levopimaric acid is shown into rosin, levopimaric acid will be referred to below as below and will be designated as adduct (II), Diels-Alder 3,523,090 A 3 a adluct (II), or just (II). The structural formula of adduct It is a still further object to convert the levopimaric (II) is acid-formaldehyde adduct by cleavage of the internal ether and rearrangement in dilute acid solution to 6 I _/ hydroxymethylabietic acid (III). (‘1112 | \ It is a still further object to convert, through hydrogen ation in the presence of a palladium-on-carbon (5%) l O/I catalyst, the 6—hydroxymethylabietic acid to 6-hydroxy (I) —9c1120 p/|\i H methyldihydroabietic acid (IV). 130°, 15-20 min. It is a still further object to conver, through hydro 10 genation in the presence of a copper-chromite catalyst X\coon Adduct (lI( the 6-hydroxymethyldihydroabietic acid to the diol (V). Puri?ed adduct (II) is somewhat unstable, and is easily This diol is a saturated compound and, as noted above, converted to 6-hydroxymethylabietic acid (III) on heat may be combined in varying proportions with other satu ing, or by treatment at room temperature with dilute rated glycols such as polyethylene glycol (e.g., poly mineral acids. ethylene glycol 2100) or with polypropylene glycol, (e.g. The structural formula for (III) is polypropylene glycol 2000) in the preparation of poly urethane foams and rubbers. It is also within the scope of our invention to convert, through reduction by means of lithium aluminum hy dride and alkaline hydrolysis, the carboxylic acid group of adduct (11) to the novel l-hydroxymethyl form of adduct which is designated herein as (VI). The latter (V1) is readily converted to (VII) by means of dilute mineral acid, and (VII) can be converted to 6-hydroxy methyltetrahydroabietinol (V) (diol) by the copperchro mite catalyst mentioned above. The details of these various objects are described in the accompanying examples wherein temperatures are ?-hydrowmethylabietic acid (III) in Centigrade degrees; B.P. is boiling point; mm. is milli Hydrogenation of (III) over a palladium-on-carbon meters pressure (mercury); OHE or (ohe) is hydroxyl (Pd-C (5% ) ) catalyst eliminated one of the double bonds equivalent and was determined by the method of C. L. and produced 6-hydroxymethyldihydroabietic acid (IV). Ogg, W. L. Porter, and C. O. Willits, Ind. Eng. Chem., The structural formula for (IV) is: Anal. Ed., 17, 394 (1945). The procedure follows: 35 MIXED INDICATOR SOLUTION COnSiSts of one part of 0.1% aqueous cresol red neu tralized with sodium hydroxide and three parts of 0.1% thymol blue neutralized with sodium hydroxide. 40 PROCEDURE Weigh a sample of any product to be treated which may contain about from 1—2.5 milliequivalents of hy droxyl and introduce into a glass—stoppered iodine ?ask. Add 3.00 ml. of a freshly prepared acetylating reagent (1 volume of acetic anhydride to 3 volumes of pyridine) ?-hydryoxynlethyldihydroabietic acid (IV) 45 using a pipet or some other means of accurate measure When IV is hydrogenated over a copper chromite ment. Moisten the glass stopper with pyridine and seat catalyst, the last double bond is removed and, simul loosely, and then place the ?ask on a steam bath and taneously, the carboxylic group is converted to a hydroxy heat for 45 minutes. Add 5—6 ml. of water and swirl to mix thoroughly. Continue heating for 2 minutes and methyl group. The resulting product is 6-hydroxymethyl 50 tetrahydroabietinol (V) frequently referred to below as then cool in tap Water. Rinse down the stopper and (diol) (abietyl glycol), or simply as (V). This is a sat sides of the ?ask with 10 ml. of butyl alcohol, and then urated glycol. add a few drops of indicator and titrate with the standard The structural formula for (V) is sodium hydroxide (0.5 N). Make a blank determination on the reagent simultaneously and similar in all respects. ([3112 O H If the sample contains any free acid or alkali, this should be determined separately and corrected for in the calculation. Calculation H2 /mIII / 60 Hydroxy equivalent (OHE): (IV) ‘ Weight of sample in mg. CuCrO a (tier of blank (ml.) —titer of sample (mg.)) /\C HzOH where Nznormality of NaOH solution. 6-hydroxymethyltetrahydroabietinol (V) ( diol) The following terms are de?ned for subsequent use in the disclosure which follows: “(n.e.)” or “ne” is neu The abietyl glycol (V) may be accomplished in a tralization equivalent and for resin acids is equal to the single step by hydrogenating the adduct (II) by means molecular weight; “HaE” is active hydrogen equivalent, of the catalyst copper chromite. i.e., the grams of the sample required to evolve 1 mole of It is a prime object of our invention to convert, step hydrogen on treatment with excess lithium aluminum hy wise, resin acids from pine gum to 6-hydroxymethyl dride (LiAll-Ii); p.s.i.g. or p.s.i. is pounds per square inch tetrahydroabietinol (diol) (V). gage; mu is millimicrons; Pd-C (5%) is 5% palladium It is a further object to ?rst prepare the levopimaric on-carbon catalyst (Girdler G 8l-C); n.m.r.