feat: add USPTO backend parser

Add a backend implementation to parse patent applications and
grants from the United States Patent Office (USPTO).

Signed-off-by: Cesar Berrospi Ramis <[email protected]>

tests/data/uspto/pftaps045931038.txt

@@ -0,0 +1,165 @@
+PATN
+WKU  045931038
+SRC  6
+APN  5253349
+APT  1
+ART  154
+APD  19830822
+TTL  Polyoxazoline compounds
+ISD  19860603
+NCL  2
+ECL  1,2
+EXA  Gibson; S. A.
+EXP  Lesmes; George F.
+INVT
+NAM  Johnson; Mark R.
+CTY  Breckenridge
+STA  MI
+ASSG
+NAM  The Dow Chemical Company
+CTY  Midland
+STA  MI
+COD  02
+CLAS
+OCL  548239
+XCL  544 88
+EDF  4
+ICL  C07D41312
+FSC  548
+FSS  239
+FSC  544
+FSS  88
+UREF
+PNO  3563920
+ISD  19710200
+NAM  Tomalia et al.
+OCL  548239
+UREF
+PNO  3682948
+ISD  19720800
+NAM  Tomalia et al.
+OCL  548239
+UREF
+PNO  3996237
+ISD  19761200
+NAM  Tomalia
+OCL  544 88
+OREF
+PAL  Hackh's Chemical Dictionary, 4ed, 1969, McGraw-Hill Book Company, p. 331.
+ABST
+PAL  Polyoxazoline compounds are prepared by reacting a polymercaptan with a
+      2-alkenyloxazoline or a 2-alkenyloxazine. The compounds so prepared have
+      at least two oxazoline or oxazine functionalities and can be employed in
+      applications where a compound having an oxazoline or oxazine functionality
+      has useful activity.
+BSUM
+PAC  BACKGROUND OF THE INVENTION
+PAR  This invention relates to polyoxazoline and polyoxazine compounds and, in
+      particular, those compounds having at least two pendant oxazoline or
+      oxazine functionalities.
+PAR  Compounds having two or more oxazoline rings are useful as crosslinking
+      agents. Previously, such compounds have been prepared a number of ways,
+      each having some limitations. Bisoxazolines have been prepared by the
+      reaction of dicarboxylic acids with monoethanolamine. This reaction is not
+      especially clean, and requires difficult purification procedures.
+      Bisoxazolines have also been prepared by reaction of hydrogen sulfide with
+      isopropenyl oxazoline. This reaction is only capable of producing
+      bisoxazolines and, thus, is not useful in preparing higher polyoxazolines.
+      Another method of preparing polyoxazolines is by homo- or copolymerization
+      of isopropenyl oxazoline. This procedure is frequently unsatisfactory as
+      it produces polyoxazolines with many pendant groups, resulting in
+      inefficient use of the oxazoline rings in crosslinking reactions. Also,
+      since the polyoxazoline has a high molecular weight, it is often not
+      convenient to handle and use.
+PAR  In view of the deficiencies of the prior art, it would be highly desirable
+      to prepare, in a relatively simple and efficient manner, a compound having
+      a plurality of oxazoline or oxazine rings.
+PAC  SUMMARY OF THE INVENTION
+PAR  The present invention is a compound comprising at least two, preferably at
+      least three, oxazoline or oxazine functionalities which result from the
+      reaction of a polymercaptan and a 2-alkenyloxazoline or a
+      2-alkenyloxazine.
+PAC  DETAILED DESCRIPTION OF THE INVENTION
+PAR  The 2-alkenyloxazolines and 2-alkenyloxazines of the present invention have
+      the general formula:
+      ##STR1##
+      wherein R is hydrogen or lower alkyl, and each of R.sup.1 -R.sup.4 is
+      independently hydrogen, alkyl, aralkyl, phenyl or inertly substituted
+      phenyl; and n is zero or one. Examples of suitable 2-alkenyloxazolines and
+      2-alkenyloxazines and their methods of preparation are catalogued in U.S.
+      Pat. Nos. 3,505,297 and 4,144,211, which are incorporated herein by
+      reference. Examples of preferred 2-alkenyloxazolines include
+      2-isopropenyloxazoline, 2-vinyloxazoline, and
+      5-methyl-2-isopropenyloxazoline.
+PAR  The polymercaptans of this invention are selected from a known class of
+      compounds having many members, and any member of this class which reacts
+      with vinyl functionalities can be employed. Polymercaptans, for purposes
+      of this invention, contain at least two, preferably at least three,
+      mercapto (i.e., --SH) groups. Although the structure of the polymercaptan
+      is not particularly critical and can vary depending upon the desired
+      application, preferred polymercaptans are those which correspond to the
+      formula R(--SH).sub.n wherein R is a hydrocarbyl or inertly substituted
+      hydrocarbyl group of from 1 to about 24 carbon atoms, most preferably from
+      1 to about 6 carbon atoms; and n is from 2 to about 10, preferably from 3
+      to about 10, most preferably from 3 to about 6. Examples of especially
+      preferred polymercaptans are pentaerythritol tetra-3-mercaptopropionate
+      and dipentaerythritol hexa-3-mercaptopropionate.
+PAR  Catalysts useful herein include the known free radical generating
+      catalysts, such as the organic peroxides, the azobis compounds, actinic
+      light, electron beams or other high energy radiation. Particularly useful
+      catalysts include the amine catalysts such as triethyl amine.
+PAR  The amount of polymercaptan which is employed is most preferably an amount
+      such that there are an equivalent number of mercapto groups and
+      2-alkenyloxazolines or 2-alkenyloxazines. Alternatively, there can be a
+      slight excess of mercapto groups over 2-alkenyloxazolines or
+      2-alkenyloxazines.
+PAR  Compounds of this invention which contain two or more oxazine or oxazoline
+      rings are prepared at very high yield in very high purity. Preferably, the
+      desired 2-alkenyloxazoline or 2-alkenyloxazine is added to an inert
+      organic solvent with an effective amount of a suitable catalyst and the
+      desired polymercaptan. It is desirable to heat the reaction mixture, as
+      for example by reflux, for a period from 1/2 to about 5 hours. The
+      compound is prepared quickly and efficiently, is obtained without
+      significant by-product and no further purification is required.
+PAR  The compounds of this invention can be reacted with ethylenically
+      unsaturated carboxylic acids as described in U.S. Pat. No. 3,996,237 which
+      is incorporated herein by reference. Thus, the compounds of this invention
+      are particularly useful in introducing crosslinking capabilities to
+      numerous polymers prepared from ethylenically unsaturated monomers.
+PAR  In addition, the compounds of this invention are useful in the various
+      other applications where a compound comprising a pendant oxazine or
+      oxazoline ring is known to have useful activity. Of particular interest is
+      the preparation of highly branched and/or crosslinked polyoxazoline and
+      polyoxazine networks. For example, the compounds of this invention can be
+      contacted with an alkyloxazine or alkyloxazoline under conditions suitable
+      to bring about oxazoline or oxazine polymerization. It is understood that
+      the greater the number of pendant oxazoline or oxazine rings per molecule
+      of compound of this invention, the greater the branching or network form
+      of the polymer so prepared.
+DETD
+PAR  The following example is presented to illustrate the invention and should
+      not be construed as limiting its scope.
+PAC  EXAMPLE 1
+PAR  To a solution comprising 5 g of pentaerythritol tetra-3-mercaptopropionate
+      in 15 ml of toluene is added 4.30 g of isopropenyl oxazoline and 0.15 ml
+      of triethylamine. The solution is heated to reflux for 2 hours and allowed
+      to cool to room temperature. The solvent is removed under reduced pressure
+      to yield the tetraoxazoline which is a clear viscous product. The product
+      has the structure:
+      ##STR2##
+PAC  EXAMPLE 2
+PAR  To a solution comprising 50 g of dipentaerythritol
+      hexa-3-mercaptopropionate in 200 ml of acetonitrile is added 42.5 g of
+      isopropenyl oxazoline and 2 ml of triethylamine. The solution is heated to
+      reflux at 80.degree. C. for 5 hours and allowed to cool to room
+      temperature. The solution is stirred for 2 days. The solvent is removed
+      under reduced pressure to yield the hexaoxazoline which is a viscous oil.
+      The product has the structure:
+      ##STR3##
+CLMS
+STM  What is claimed is:
+NUM  1.
+PAR  1. A compound having the structure:
+NUM  2.
+PAR  2. A compound having the structure:
+      ##STR4##