US3509146A - Process of preparing phthalocyanine and heterocyclic analogues - Google Patents

Description

United States Patent M 3,509,146 PROCESS OF PREPARING PHTHALOCYANINE AND HETEROCYCLIC ANALOGUES Lester Weinberger, Peufield, Paul J, Brach, Rochester, and Steven J. Grammatica, Webster, N.Y., asslgnors to Xerox Corporation, Rochester, N.Y., a corporation of New York No Drawing. Filed July 3, 1967, Ser. No. 650,589 Int. Cl. C09b 47/06 U.S. Cl. 260-250 8 Claims ABSTRACT OF THE DISCLOSURE A process for the preparation of an organic pigment which comprises mixing under reaction conditions a reactant consisting of a 1,3-diimino-isoindoline (substituted or unsubstituted) or a heterocyclic analogue of 1,3-diimino-isoindoline and an alkylalkanolamine.

BACKGROUND OF THE INVENTION This invention relates in general to a process for the preparation of organic pigments and, more specifically, to a process for the preparation of phthalocyanine and heterocyclic analogues of phthalocyanine.

There have been known various methods for the production of images, such as photography, offset, xerography, and the like. In Xerography, as disclosed by C. F. Carlson in U.S. Patent 2,297,691, a base plate of relatively low electrical resistance, such as metal, paper, etc., having a photoconductive insulating surface coated thereon, is elect-rostatically charged in the dark. The charged coating is then exposed to a light image. The charges leak ofi rapidly to the base plate in proportion to the intensity of light to which any given area is exposed. The charges are substantially retained in the non-exposed areas. After such exposure the coating is contacted with electrostatic solid marking particles in the dark. These particles adhere to the areas where the electrostatic charges remain, forming a powder image corresponding to the electrostatic image. This method is further disclosed in U.S. Patents 2,659,670, 2,753,308, and 2,788,288. The powder image can be transferred to a sheet of transfer material, resulting in a positive or negative print as the case may be. Alternatively, where the base plate is relatively inexpensive, it may be desirable to fix the powder image directly to the plate itself. A full description of the xerographic process may be found in a book by Dessauer and Clark, entitled, Xerogr-aphy and Related Processes (Focal Press Limited, 1965).

In xerography, there are known many photoconductive materials, some of which function in a reusable system and others which function commercially only in a one-shot o-r disposable system. In the reusable system, while many photoconductors have been used or attempted, selenium has been the most commercially accepted material for use in electrographic plates.

Although selenium is the most desirable photoconductor known today for use in electrophotography, it does have some inherent disadvantages. For example, one disadvantage of the use of selenium is that it is not fully panchromatic, being sensitive only to wavelengths shorter than about 5,800 A.U. Secondly, electrographic plates made with selenium are expensive to manufacture. A third drawback to the use of selenium is the degree of difiiculty encountered when depositing this material upon a substrate to form an electrographic plate. Finally, it is known that vitreous selenium layers are only meta-stable and may be recrystallized into unsuitable crystalline forms at temperatures only slightly in excess of those prevailing in conventional electrophotographic machines.

In U.S. Patent 2,663,636, Arthur Middleton disclosed 3,509,146 Patented Apr. 28, 1970 various methods and means whereby any photoconductive insulating material in an insulating resin binder can be formed into an operable xerographic plate. In a copending application, Serial No. 375,191, filed in the United States Patent Ofiice on June 15, 1964, entitled, Electrographic Element, the use of phthalocyanine in a resin binder is disclosed as a xerographic plate. There are many advantages spelled out in this application especially directed to the use of phthalocyanine in a reusable xerogr-aphic system. Various phthalocyanines are disclosed as suitable for use in a xerographic plate, as are many binders, both photoconductive and nonphotoconductive.

There has recently been developed an electrophoretic imaging system capable of producing color images which utilizes electrically photosensitive particles, typically phthalocyanine. This process is described in detail in copending applications, Ser. Nos. 384,737, 384,680, and 384,681, all filed July 23, 1964. In such an imaging system, various colored light absorbing particles are suspended in a non-conducting liquid carrier. The suspension is placed between electrodes, one of which is generally conductive called the injecting electrode and the other of which is generally insulating and called the blocking electrode. One of these electrodes is at least partially transparent. The suspension is subjected to a potential difference between the electrodes across the suspension and exposed to an image through said partially transparent electrode. As these steps are completed, selective particle migration takes place in image configuration providing a visible image at one or both of the electrodes. An essential component of the system is the suspended particles which must be electrically photosensitive and which apparently undergo a net change in charge polarity upon exposure to activating electromagnetic radiation through interaction with one of the electrodes.

In a monochromatic system, particles of a single color are used, producing a single-colored image equivalent to conventional black-and-white photography. In a polychromatic system, the images are produced in natural color because mixtures of particles of two or more different colors which are each sensitive to light of a specific wavelength or narrow range of wavelengths are used.

Phthalocyanine, also known as tetrabenzotetraazaporphin and tetrabenzoporphyrazine, may be said to be the condensation product of four isoindole groups. Metal-free phthalocyanine has the following general structure:

In addition to the metal-free phthalocyanine of the above structure, various metal derivatives of phthalocyanine are known in which the two hydrogen atoms in the center of the molecule are replaced by metals from any group of the periodic table. Further, it is well known that from one to sixteen of the peripheral hydrogen atoms in the four benzene rings of the phthalocyanine molecule may be replaced by halogen atoms and by numerous organic and inorganic groups.

In the preparation of organic photoconductive pigments, such as metal-free phthalocyanine, for xerographic and other electrostatic purposes, many ditficulties have been encountered. The use of metal-free phthalocyanine in electrostatic applications places stringent requirements on the purity of this material. For'example, it is required that the phthalocyanine intendedjtor use in a xerographic plate generally be free of impurities or contaminantswhich in one way or another interfere with the xerographic system, whether it be in the charge acceptance or charge dissipation step or other steps in the electrographic process. Until now, phthalocyanine has been prepared almost exclusively for use as a pigment where color, tinctorial strength, light fastness, dispersibility, etc., are prime considerations and purity is incidental. As a result, reported'methods of synthesis (see Phthalo'cyanine Compounds, by Moser and Thomas, Rheinhold Publishing Company, pages 104-189) often introduce undesirable metallic or organic impurities which are diflicult to remove. Two general methods have been used for the manufacture of metal-free phthalocyanine: (1) indirectly from an acid and a metal phthalocyanine containing a replaceable metal and (2) directly from phthalonitrile.

Methods that include forming a' metal phthalocyanine with a replaceable metal which is subsequently removed with an acid are: heating phthalonitrile with a sodium alcoholate (U.S. Patent 2,116,602; British Patent 410,814; US. Patent 2,699,441), heating phthalonitrile with sodium cyanamide (U.S. Patent 2,154,912), heating phthalonitrile with sodium cyanamide and a solvent (U.S. Patent 2,182,763; British Patent 462,239), heating phthalonitrile with calcium metal in an alcohol or with calcium or barium oxides (U.S. Patent 2,202,632), heating phthalonitrile with calcium oxide and methylglucamine (U.S. Patent 2,413,191), heating phthalonitrile with an alcohol and sodium hydride (Swiss Patent 297,412; German Patent 297,412; German Patent 933,047), heating phthalonitrile with magnesium and a solvent under pressure (British Patent 466,042; British Patent 482,387). Other methods for making labile metal phthalocyanines include those of Linsteads and Thorpes early patents (U.S. Patent 2,000,051; U.S. Patent 2,000,052; British Patent 389,842) using cyano-benzamide or phthalamidie as the phthalo- 'cyanine forming intermediate and magnesium metal. A magnesium phthalocyanine is apparently formed by the action of a Grignard reagent such as methyl magnesium iodide with phthalonitrile (British Patent 466,042; British Patent 480,249). Tin phthalocyanine may be prepared by a urea phthalic anhydride solvent process, but without ammonium chloride (U.S.. Patent 2,197,459).

The above-mentioned methods of synthesis generally introduce metals which are ditticult to remove. Methods of removing metal from labile phthalocyanines include: placing a solution of tin phthalocyanine in concentrated sulfuric acid, followed by drowning in water (U.S. Patent 2,197,459), boiling an alkali or alkali earth metal phthalocyanine with hydrochloric acid (U.S. Patent 2,216,761,), or stirring an alkali metal phthalocyanine with cold methyl alcohol, diluting with warm water, and filtering (U.S. Patent 2,214,454). Heating an alkali metal phthalocyanine with the ammonium salt of a strong acid converts it to beta phthalocyanine (U.S. Patent 2,686,184).

- One general method of preparing phthalocyanine which may avoid substantial metallic contaminants is to heat phthalonitrile to 350-360 C. for 7 hours in a sealed vessel (U.S. Patent 2,116,602; British Patent 410,814; US. Patent 2,153,620). A second method of synthesis which may avoid substantial metallic contaminants is to heat phthalonitrile in dimethylaniline or invquinoline solution While passing gaseous ammoniarthroughthe solution; temperatures are maintained in the vicinity of 250 C. (U.S. Patent 2,116,602; British Patent 410,814; US. Patent 2,153 ,620)..A third method of synthesis which'may avoid substantial metallic contaminants is to heat phthalonitrile with acetamide and/or-formamide to the boil for 8 hours (U.S..Patent- 2,182,763; British Patent 462,239; US. Patent 2,212,924; British Patent 457,526). A fourth method is to heat phthalonitrile with dihy r xybenzene. g yco or glycerin (British Patent'466,042)'. A fifth method consists of heating phthalonitrilein an inert solvent in the presence of cyclohexylamine or piperidine (U.S. Patent 2,485,167). A sixth method is to heat phthalonitrile in a solvent With potassium carbonate, piperidine, and ethylene glycol (U.S. Patent 2,485,167; US. Patent 2,485,168). Finally, a seventh method of synthesis of phthalocyanine which may avoid substantial metallic contaminants is to add. a catalytic amount of triethanolamine to molten phthalonitrile at temperatures of 170 to 180C. (U.S. Patent 2,155,054).

While the above seven methods of phthalocyanine synthesis avoid the introduction of inetal impurities, side reactions occur with a resulting lower yield of pigment due to the high temperatures at which these methods of synthesis are carried out. In addition, complex organic impurities are introduced. These organic impurities are difficult to remove and cannot be tolerated in the phthalocyanine compound when it is to'be used for electrostatic purposes. It is, therefore, an object of this invention to provide a method for the preparation of a substantially pure organic pigment devoid of the above-noted disadvantages.

It is, another object of this invention to provide a direct method for the preparation of an organic pigment without the use of metals or metallic salts, whereby substantially all contaminants in the final product are avoided.

It is still another object of this invention to provide a direct method for the preparation of a substantially pure organic pigment wherein the yield of the resulting product is significantly high.

It is still another object of thisinvention to provide a direct method for the preparation of a substantially pure organic pigment Which takes place under mild reaction conditions.

It is yet another object of this invention to provide a direct method for the preparation of a substantially pure organic pigment wherein the final product has excellent properties for use in an electrostatic imaging system.

It is still another object of this invention to provide a method for the preparation of an organic pigment in which there is ease of isolation and purification of the resulting product.

It is still another further object of this invention to provide a low-cost method for the preparation of substantially pure organic pigment.

SUMMARY OF THE INVENTION The foregoing objectives, and others, are accomplished in accordance with this invention, generally speaking, by providing a novel system for the preparation of a highly pure organic photoconductive pigment which comprises mixing under reaction conditions an alkylalkanolamine and a 1,3-diimino-isoindoline or a heterocyclic analogue of 1,3-diimino-isoindoline.

Any suitable ratio of 1,3-dimino-isonodoline or heterocyclic analogue of 1,3-diimino-isoindo1ine to alkylalkanolamine may be employed in this process. However, best yields of the desired resulting products are obtained when this ratio is from approximately 1:5 parts, by weight, to approximately 1:10 parts, by Weight. Best yields are obtained by employing a ratio of approximately 1 part, by weight, of 1,3-diimin0-is0indoline or 1 part, by weight, of a heterocyclic analogue of 1,3-diimino-isoindoline to approximately 5'parts, by weight, of alkylalkanolaminc;

Although the reaction may becarried out at any suitable temperature, the range of about C. to about 280 C. has been found convenient. While any appropriate temperature may be used depending upon the com.- ponents selected for this system, it is preferred that a temperature generally in the. range of about 100 C. to about C. be used because at this temperature it is found that fewer'side reactions occur and a purer prodduct is obtained.

Any suitable alkylalkanolamine may be used in this system. Typical alkylalkanolamines are Z-dimethylaminoethanol, 1-dimethylamino-Z-propanol, 1-diethylamino-2-propanol, Z-dimethylamino-Z-methyl-l-propanol, 2-diethylaminoethanol, 3-dimethylamino-l-propanol, 2-(di-iso-propylamino) ethanol, Z-butylaminoethanol, Z-dibutylaminoethanol, 2[(2-(diethylamino) ethyl) amino]ethanol 2,2'-(butylimino) diethanol, Z-ethylaminoethanol,

2,2'-(ethylimino) diethanol, Z-methylaminoethanol, 2,2'-(methylimino) diethanol, 2-(iso-propylamino) ethanol, 2,2'-(isopropylimino) diethanol, 2,2'-(tert.-butylimino) diethanol, and 3-diethylamino-l-propanol, among others.

Although any suitable alkylalkanolamine may be used in this system, it is preferred that Z-dimethylaminoethanol (reflux temperature, about 131 C. to 135 C.), l-dimethylamino-2-propanol (reflux temperature, about 126 C.- 127 C.), or 1-diethylamino-2-propanol (reflux temperature, about 153 C.-160 C.) be used because higher yields of substantially pure organic pigment are obtained. Optimum results are obtained with 2-dimethylaminoethanol.

Although any suitable 1,3-diimino-isoindoline or substituted or unsubstituted heterocyclic analogue of 1,3-diimino-isoindoline may be used in this system, it is preferred that unsubstituted 1,3-diimino-isoindoline,

5 -nitro-1 3-diimino-isoindoline, S-acetamido-l,3-diimino-isoindoline,

4,5 ,6,7-tetrachloro-l ,3-diimino-isoindoline, 4,5 ,6,7-tetrabromo-1,3-diimino-isoindoline, 5 -chloro- 1,3-diimino-isoindoline,

the unsubstituted or halogen, CF S N0 CN, NH;, CH C H C3H7, or C H substituted pyrazino analogue of 1,3-diimino-isoindoline, unsubstituted or halogen, CF S0 N0 CN, NH CH C H C3H7 or C H substituted 1,3-diimino-4,7-dithia-4,5,6,7-tetrahydro-isoindoline, the unsubstituted or halogen, CF S0 N0 CN, NH CH C H C H or C H substituted quinaline analogue of 1,3-diimino-isoindoline, orthe unsubstituted or halogen, CF13, S03, N02, CN, NHg, CH3, C2H5, C3H7 01' C4H9 substituted pyridine analogue of 1,3-diimino-isoindoline be used to obtain organic pigments of high photoconductivity.

While any suitable 1,3-diimino-isoindoline may be used in this process, it is most preferred that unsubstituted 1,3- diimino-isoindoline be employed in order that an end product with substantially greater photoconductivity and panchromaticity, namely metal-free phthalocyanine, be obtained. While any suitable analogue of 1,3-diiminoisoindoline may be used in this system, it is most preferred that the unsubstituted pyrazino analogue be employed in Order to obtain a. substantially pure organic pigment of excellent photoconductivity.

DESCRIPTION OF PREFERRED EMBODIMENTS The following examples will further define various preferred embodiments of the present invention. Parts and percentages are by weight unless Otherwise specified.

Example I About 1 part, by weight, of 1,3-diimino-isoindoline and about 5 parts, by weight, of 2-dimethylaminoethanol are placed in a flask equipped with a mechanical stirrer and thermometer. The suspension is stirred and heated to reflux (about 131 C. to about 135 C.). This temperature is maintained for approximately 10 minutes during which time NH is given 01?. The above mixture is then filtered hot and the residue is washed thoroughly, first with water and then with acetone. Finally, the residue is air-dried. The resulting product consists of very pure beta metalfree phthalocyanine. Exhaustive extraction with hot dimethylformamide and isopropanol show the presence of less than 0.1% liquid and solid impurities. The yield of the said product is about of the theoretical yield.

Example II About 1 part, by weight, of 1,3-diimino-isoindoline and about 12 parts, by weight, of Z-dimethylaminoethanol are placed in a flask equipped with a mechanical stirrer and thermometer. The suspension is stirred and heated to reflux (about 131 C. to about 135 C.). This temperature is maintained for approximately 25 minutes during which time NH is given off. The above mixture is then filtered hot and the residue is washed thoroughly, first with acetone and then with methanol and water. Finally, the residue is dried in a vacuum for approximately 6 hours at approximately 55 C. The resulting product consists of very pure beta metal-free phthalocyanine. Exhaustive ex traction with hot dimethylformamide and isopropanol show the presence of less than 0.1% liquid and solid impurities. The yield of said product is about 85% of the theoretic yield.

Example III About 1 part, by weight, of 1,3-diimino-isoindoline and about '8 parts, by weight, of 1-dimethylamino-Z-propanol are placed in a flask equipped with a mechanical stirrer and thermometer. The suspension is stirred and heated to reflux (about 126 C. to about 127 C.). This temperature is maintained for approximately 30 minutes during which time NH is given otf. The above mixture is then filtered and the residue is washed thoroughly, first with water and then with ethanol. Finally, the residue is air-dried. The resulting product consists of very pure beta metal-free phthalocyanine. Exhaustive extraction with hot dimethylformamide and isopropanol show the presence of less than 0.1% liquid and solid impurities. The yield of said product is about 85% of the theoretical yield.

Example IV About 1 part, by weight, of S-nitro-1,3-diimino-isoindoline and approximately 6 parts, by weight, of l-diethylamino-Z-propanol are placed in a flask equipped with a mechanical stirrer and thermometer. The suspension is stirred and heated to reflux (about 153 C. to about C.). This temperature is maintained for approximately 5 hours during which time NH is given off. The above mixture is then filtered hot and the residue is washed thoroughly, first with water and then with acetone and ethanol. Finally, the residue is air-dried. The resulting product consists of very pure tetra (4) nitro-phthalocyanine. Exhaustive extraction with hot dimethylformamide and isopropanol show the presence of less than 0.1% liquid and solid impurities. The yield of said product is about 85% of the theoretical yield.

Example V About 1 part, by weight, of 5-acetamido-1,3-diiminoisoindoline and about 9 parts, by weight, of Z-dirnethylamino-Z-methyl-l-propanol are placed in a flask equipped with a mechanical stirrer and thermometer. The suspension is stirred and heated to reflux (about 159 C. to about 161 C.). This temperature is maintained for approximately 6 hours during which time NH is given off. The above mixture is then filtered hot and the residue is washed thoroughly, first with acetone and then with water. Finally, the residue is dried in a vacuum for approximately 5 hours at about 60 C. The resulting product consists of very pure tetra (4) acetamidophthalocyanine. Exhaustive extraction with hot dimethylformamide and isopropanol show the presence of less than 0.1% liquid and solid impurities. The yield of said product is about 80% of the theoretical yield.

Example VI About 1 part, by weight, of 4,5,6,7-tetrachloro-l,3-diirnino-isoindoline and about parts, by Weight, of 2- diethylaminoethanol are placed in a flask equipped with a mechanical stirrer and thermometer. The suspension is stirred and heated to reflux (about 161 C. to about 163 C.). This temperature is maintained for approximately 4 hours during which time NH is given ofi. The above mixture is then filtered and the residue is washed thoroughly, first with ethanol and then with acetone. Finally, the residue is air-dried. The resulting product consists of very pure hexadecachlorophthalocyanine. Exhaustive extraction with hot dimethylformamide and isopropanol show the presence of less than 0.1% liquid and solid impurities. The yield of said product approaches 80% of the theoretical yield,

Example VII About 1 part, by weight, of 4,S,6,7-tetrabromo-1,3-diimino-isoindoline and about parts, by weight, of 3-dimethylamino-l-propanol are placed in a flask equipped with a mechanical stirrer and thermometer. The suspension is stirred and heated to reflux (about 165 C. to about 167 C.). This temperature is maintained for approximately 6 hours during which time NH is given off. The above mixture is then filtered hot and the residue is washed thoroughly, first with acetone and then with water and ethanol. Finally, the residue is air-dried. The resulting product consists of very pure hexadecabromophthalocyanine. Exhaustive extraction with hot dimethylformamide and isopropanol show the presence of less than 0.1% liquid and solid impurities. The yield of said product is about 80% of the theoretical yield.

Example VIII About 1 part, by weight, of 5-chloro-1,3-diiminoisoindoline and about 7 parts, by weight, of Z-(di-isopropylamino) ethanol are placed in a flask equipped with a mechanical stirrer and thermometer. The suspension is stirred and heated to reflux (about 191 C. to about 193 C.). This temperature is maintained for approximately 5 hours during which time NH is given ofi. The about mixture is then filtered hot and the residue is washed thoroughly, first with water and then with acetone. Finally, the residue is dried in a vacuum for approximately 7 hours at about 50 C. The resulting product consists of very pure tetra (4) chlorophthalocyanine. Exhaustive extraction with hot dimethylformamide and isopropanol show the presence of less than 0.1% liquid and solid impurities. The yield of said product is about 80% of the theoretical yield.

Example IX About 1 part, by weight, of the pyrazino analogue of 1,3-diimino-isoindoline, having the structure:

ifiIH N it is dried in a vacuum for approximately 7 hours at about 50 C. The resulting product consists of an organic pigment having the structure:

NH HN A N C C .a/ at N N Ly Exhaustive extraction with hot dimethylformamide and isopropanol show the presence of less than 0.1% liquid and solid impurities. The yield of said product is about of the theoretical yield.

Example X About 1 part, by weight, of chlorine substituted 1,3- diimino 4,7-dithia-4,5,6,7-tetrahydro-isoindoline, having the structure:

ethanol. Finally, it is air-dried. The resulting product consists of an organic pigment having the structure:

Exhaustive extraction with hot dimethylformamide and isopropanol show the presence of less than 0.1% liquid and solid impurities. The yield of said product is about 80% of the theoretical yield.

Example XI Aboutl part, by weight, of the methyl substituted quinaline analogue of 1,3-diimino-isoindolin, having the structure:

s ur on and approximately 8 parts, by weight, of 2 [(Z-diethylamino)]ethanol are placed in a flask equipped with a mechanical stirrer and thermometer. The suspension is stirred and heated to reflux (about 240 C. to about 243 C.). This temperature is maintained for approxi mately 1 hour during which time NH is given 01f. The above mixture is then filtered, and the residue is washed thoroughly, first with water and then with acetone. Finally, it is dried in a vacuum for approximately 6 hours at about 55 C. The resulting product consists of an organic pigment having the structure:

Exhaustive extraction with hot dimethylformamide and isopropanol show the presence of less than 0.1% liquid and solid impurities. The yield of said product is about 75% of the theoretical yield.

Example XII About 1 part, by weight, of the pyridine analogue of 1,3-diimino-isoindoline, having the structure:

and about 6 parts, by weight, of 2-diethylaminoethanol are placed in a flask equipped with a mechanical stirrer and thermometer. The suspension is stirred and heated to reflux (about 161 C. to about 163 C.). The temperature is maintained for approximately 1 /2 hours during which time NH is given ofl. The above mixture is filtered hot, and the residue is washed, first with water and then with methanol. Finally, it is air-dried. The resulting product consists of an organic pigment having the structure:

Exhaustive extraction with hot dimethylformamide and isopropanol show the presence of less than 0.1% liquid and solid impurities. The yield of said product is about 80% of the theoretical yield.

While specific components of the present system are defined in the working examples above, any of the other typical materials indicated above, if suitable, may be substituted in the working examples. In addition, many other variables may be introduced in the present process such as further purification steps or other reaction compOnents which may in any way affect, enhance, or otherwise improve the present process.

While various specifics are given in the present application, many modifications and ramifications will occur to those skilled in the art upon reading of the present disclosure. These are intended to be encompassed within the scope of this invention.

What is claimed is:

1. The process for the preparation of a member selected from the group consisting of tetraazaporphins and where A is selected from the group consisting of and where R is selected from the group consisting of H, a halogen, CF SOgH, N0 CN, NH CH C H C H and C H and where n is a positive integer from 1 to 2 and m is a positive integer from 1 to 3, and combinations thereof;

(b) heating said mixture to reflux temperature; and

(c) maintaining said temperature for a period of about 10 minutes to about 7 hours.

2. The process according to claim 1 wherein said alkylalkanolamine is selected from the group consisting of 2-dimethylaminoethanol, l-dimethylamino 2 propanol, and 1-diethylamino-2-propanol.

3. The process according to claim 1 wherein said substituted 1,3-diimino-isoindoline is selected from the group consisting of S-nitro-l, S-diimino-isoindoline, S-acetamido-l, 3-diimino-isoindoline, 4,5,6,7-tetrachloro-1, 3-diimino-isoindoline, 4,5,6,7-tetrabromo 1, 3 diimino-isoindoline, and S-chloro-l, 3-diimino-isoindoline.

4. The process according to claim 1 wherein the ratio of said alkylalkanolamine to said reactant ranges from about 5:1, by weight, to about 10:1, by weight.

5. The process according to claim 1 wherein said alkylalkanolamine is Z-dimethylaminoethanol.

6. The process according to claim 1 wherein said re- References Cited actant is unsubstituted 1,3-diimino-isoindoline. UNITED STATES PATENTS 7. The process according to claim 1 wherein said re- 2,752,346 6/1956 R5Sch et 1 5 actant is the unsubstituted pyrazino analogue of 1,3-dir HENRY R- ULES, Primary Examiner immoisolndoline. 0

8. The process according to claim 1 wherein the ratio MOATZ Assistant Examiner of said alkylalkanolamine to said reactant is about 5:1, US. Cl. X.-R.

y Weight 260-288, 296, 314.5