Novel dicarboxylic acids containing diketopiperazine groups and polyesters prepared therefrom
United States Patent Lee et al.  
 [111 3,876,583 [451 Apr. 8.1975  
 [75] Inventors: Lester T. C. Lee. Parsippany; Eli M.  
 Pearce, Somerville. both of N.J.; Morton H. Litt. University Heights. Ohio [73] Assignee: Allied Chemical Corporation, New  
 York. NY.  
 [22] Filed: Mar. 14, 1974 [21] Appl. No.: 451,329  
  Related U.S. Application Data [62] Division of Ser. No. 328.216. Jan. 31. 1973. Pat. No. 3.817.943. which is a division of Ser. No. 39.510. May 21, 1970. Pat. No. 3728.348.  
 [52] U.S. Cl 260/75 N: 260/33.4 P [51] Int. Cl. C08g 17/06 [58] Field of Search 1. 260/75 N [56] References Cited UNITED STATES PATENTS 3.513.127 5/1970 Marans 260/75 N X 3.515.747 6/1970 Marans 160/75 N X 3.553.215 1/1971 Zalewski 260/248 3.558.630 1/1971 Moyer.... 260/268 3.577.371 5/1971 Blair 260/75 N X 3.763.091 10/1973 Crcscenzi et al. 260/75 N X Primary E.\&#39;aminerHoward E. Schain Attorney. Agent, or FirmArthur J. Plantamura [57] ABSTRACT Dicarboxylic acids having the formula wherein R, represents a phenylene or alkylene radical and R represents a divalent organic radical. are prepared by reacting a tricarhoxylic acid having the formula HOOCR,N(CH COOH) such as nitrilotriacetic acid. with a diamine having the formula H NR NH such as hexame thylene diamine. in a substantially 2:1 molar ratio in the presence of an inert solvent. The dicarboxylic acids are useful as monomers in preparing linear film and fiber-forming polyamides and polyesters in accordance with conventional methods for preparing such polymers from dicarboxylic acids.  
 4 Claims, No Drawings NOVEL DICARBOXYLIC ACIDS CONTAINING is a phenylene radical or an alkylene radical having 1 DIKETOPIPERAZINE GROUPS AND POLYESTERS to 6 carbon atoms. As used herein. the term alkylene PREPARED TI-IEREFROM radical&#34; refers to alkyl diradicals having the general This is adivision of application Ser. No, 328,216 now formula C,,H Especially good results are ob- U.S. Pat. NO. 8179 3. filed J m- 31. 1973. which in 5 tained using nitrilotriacetic acid. Furthermore, nitriloturn is a divisional of Scr. No. 39,510, filed May 21. triacetic acid is an inexpensive compound sold com- 1970, HOW mercially in large quantities, so that a particularly ad- This invention relates to certain novel dicarboxylic m ou feature of this invention is that it permits a ids, their m th d f preparation. a 0 linellr p ythe preparation of valuable linear polymers containing mer$- Particularly Polyamldes and P S prepared diketopiperazine groups derived from this inexpensive therefrom. compound The dicarboxylic acids of this invention have the for- Di i uitablg f preparing h di b li mum acids of this invention have the formula H NR NH CH C C CH 2 2 HOOC P. N N F. N N R COOH I CH g (3 0.1  
 wherein R, represents a phenylene or alkylene radical wherein R is a divalent organic radical. and include. in and R represents a divalent organic radical. These diparticular. aliphatic, aromatic, and aliphatic-aromatic carboxylic acids are prepared by reacting a tricarboxdiamines and substituted derivatives thereof. Suitable ylic acid having the formula HOOCR,N(CH COOH)- aliphatic diamines include straight chain aliphatic diwith a diamine having the formula H NR NH in a subamines, such as l,l0-diaminodecane, branched chain stantially 2:1 molar ratio in the presence of an inert solaliphatic diamines, such as 2-methyl-1,6- vcnt at a temperature of 40 to 220C. as represented diaminohexane, and cycloaliphatic diamines. such as by the following equation cyclohexanediamine. The aliphatic chain can contain O \//O H CH C C CH HOOC R N N R N N R COOl-i Cl-i C O E CH The time required for completion of the reaction is hetero atoms, such as sulfur or oxygen, such as reprenormally about 2 hours or more, up to about ten hours. sented by 3,3-ethylenedioxybis(propylamine). and can The product crystallizes from the reaction mixture also bear substituents, such as halogen atoms, which P Cooling to room tel&#39;nlml&#39;amre and can be feeOV- are nonreactive under the conditions of polymerizaered from the reaction mixture in accordance with connon, The di i can l t i a a ti ventional methods, such as by filtration. cleus, such as represented by p-Xylylenediamine. Other The reaction is conveniently rri d o t t th reflux aromatic diamines suitable for use in this invention intemperature of the reaction mixture. Hence, it is desirelude iamine h r in R2 in the general formula is able to employ a solvent having a boiling point within phenylene, a fused aromatic group, such as naphthythe temperature range for the reaction, which is preferlene, or two or more linked aromatic nuclei, such as ably from about 80C to about 180C. Suitable inert represented by biphenylene, bisphenylenemetha e. solvents include liquid polar organic solvents, such as bisphenylenepropane, bisphenylenesulphone, bisphedimethylformamide, dimethylacetamide, dimethylsulfnylene ether an the hi addition, ny Of the oxide, tetrahydrofuran, and the like. It is desirable, but matic groups may bear one or more nuclear substitunot essential,to addasmallamountofatertiary amine, ents, such as lower alkyl groups or halogen atoms, such as triethylamine, to the reaction mixture to prowhich are nonreactive under the conditions of polymote imide formation. The desired product is normally merization. The diamine preferably contains from 2 to obtained at a high yield and is recovered in accordance 18 carbon atoms, more preferably 4 to 12 carbon with conventional methods, such as by filtration. atoms. Particularly suitable diamines include diamines Tricarboxylic acids suitable for use in this invention of the homologous Series z z)&#34; 2 wherein is have the formula HO()CR N(CH COOH)-&#39; wherein R, an integer from 2 to 12, preferably 4 to 8, and diamines Of the gen a formula 2 2),, 2) 2 amides can be prepared from such diamines in accorwherein Z is a phenylene radical and p and q are indedance with this invention by employing conventional pendently 0, l, 2 or 3. solution polymerization techniques using an inert polar The dicarboxylic acids of this invention are useful in organic solvent, such as dimethylformamide. preparing linear polyesters and polyamides in accor- The polyesters of this invention can be prepared in dance with conventional methods for preparing such accordance with conventional polyesterification procepolymers from dicarboxylic acids. For example, polydures in which the dicarboxylic acid is employed diamides are prepared by polymerizing the dicarboxylic rectly or as the corresponding diacid chloride or lower acid with a diamine having the formula H NR NH alkyl diester. For example, the polyesters of this invenwherein R is a divalent organic radical such as defined tion are conveniently prepared by direct esterification herein for R (including the preferred embodiments polymerization by heating the dicarboxylic acid with thereof). Such polyamides have recurring units of the the diol in the presence of a suitable catalyst in an inert formula atmosphere at about l50200C until evolution of II II 0 CH c c c&#39;a o u 2 Y 2 -C-R-N N-R-N N-R-C-NH-R-Nl-i- CH C 2 n 8 CH2 O O ,1  
 wherein R R and R are as defined herein. Similarly, 2 water is substantially complete, followed by continued polyesters are prepared by polymerizing the dicarboxheating at higher temperatures (up to 280C) and re-.  
 Y acid Whh diol having the fQrmula 4OH duced pressures (e.g. 0.5 mm Hg) until a polymer of wherein R is a divalent organic radical such as defined film-forming molecular weight is obtained. It is norherein for R (including the preferred embodiments mally desirable to employ an excess of the diol reactant thereof). Such polyesters have recurring units of the to compensate for physical losses during polymerizaformula tion. Suitable polyesterification catalysts are wellll ll 0 CH C C CH 0 II --CP--N N-R-N il-R-C-O-R-O- CH C 2 n if CPZ 0 wherein R R and R, are as defined herein. known and are normally employed in an amount of The polyamides of this invention are conveniently 0.0l-0.5% by weight. Typical catalysts include tri-&#39; prepared by polymerizing the salt of the dicarboxylic phenylphosphite and antimony trioxide.  
 acid and the diamine. The polymerization is carried out The polyamides and polyesters prepared in accorby ma g the Stilt at an elevated temperature. g dance with this invention are particularly useful in crally between abou 200C and Until a p y forming fibers and films having desirable properites, of mm fiber-forming molecular weight 55 Obtained including excellent high temperature properties. More The time required for such polymerization is normally particularly, h polymers are h n bl h about one hour or more &#34;P to about Seven hours- The high glass transition temperatures, and yet are melt polymerization is preferably carried out under an inert processable. The polymers can be formed into fibers atmosphere Such as nitrogen and also under reduced and films by conventional melt methods as well as by pressure to facilitate removal of the water of condensaconventional l i h d Fil f h polymers hon to allow for its expahsioh a Closed y are potentially useful as separatory membranes. The  
  The salt employed in the polym riz i n is readily polymers can also be blended with other polymers to prepared by dissolving a substantially l:l molar ratio of improve their properties, especially their thermal stathe dicarboxylic acid and the diamine in an inert Polar bility. In addition to being useful in forming fibers and organic solvent such as dimethylformamide. The salt is films, the polymers f thi i vention can also be molded preferably formed under anhydrous co The to form shaped articles, especially for electrical applisalt normally forms immediately and is recovered from cations because of the good dielectric properties of the the solvent in accordance with conventional methods, polymers. The polymers can also be used to form adhesuch as by filtration. sive compositions comprising a solution of the polymer The salt polymerization procedure is generally limin a volatile, polar organic solvent, such as tetrahydroited to diamines wherein each amino group is directly 5 furan.  
 attached to a methylene group. Diamines having amino The following examples further illustrate the invengroups attached directly to aromatic nuclei do t tion. In each example, the dicarboxylic acids and polyreadily form salts with carboxylic acids; howe er, p lymer structures as conforming to the general formulas EXAMPLE 1 Preparation of Dicarboxylic Acid A solution of 1.94 grams (16.7 mmoles) of hexamethylene diamine in dimethylformamide and ml of toluene was added to a stirred solution of 6.4 grams (33.4 mmoles) of nitrilotriacetic acid and dimethylformamide maintained under a nitrogen atmosphere. A total of 80 ml of dimethylformamide was employed. A white salt formed rapidly. The temperature of the reaction mixture was raised gradually and as it reached 130C the salt began to dissolve and water of condensation began to form, indicating imide formation. Heating was continued until the reaction mixture began to reflux at 150C. The theoretical amount of water was collected after the reaction mixture had refluxed for 4 hours. The solution was then allowed to cool to room temperature and chloroform was added to precipitate a white solid, which was recovered by filtration. The product weighed 8.17 grams and was identified as a symmetrical dicarboxylic acid conforming to the general formual for the dicarboxylic acids of this invention.  
 Preparation of Polyamide by Salt Polymerization The dicarboxylic acid was dissolved in 50 ml of dimethylformamide and combined with an equal molar amount of hexamethylene diamine (1.89 grams) in ml of dimethylformamide. The salt which formed was recovered by filtration and introduced into a polymerization tube which was subsequently purged with nitrogen, subjected to a vacuum and sealed. The sealed tube was maintained at 220C for 3 hours, and at 240C for minutes. The polymer which formed was washed with water, dried under a vacuum, and found to weigh 9.80 grams (95% yield). The polymer was soluble in formic acid, sulfuric acid and m-cresol. The polymer had an inherent viscosity (0.5% in m-cresol) of 0.69, a glass transition temperature of 75C, and a melting point of 210C. A tough, flexible film was formed by melting the polymer.  
 EXAMPLE 2 Preparation of Dicarboxylic Acid To a stirred solution of 8.67 grams (46.0 mmoles) of nitrilotriacetic acid in 50 ml of dimethylformamide maintained under a nitrogen atmosphere, there was added 10 ml of benzene, 1.0 ml of tri-n-propylamine, and a solution of 1.36 grams (23.0 mmoles) of ethylene diamine. The reaction mixture was heated to reflux and the theoretical amount of water was obtained after 3 hours.  
 Preparation of Polyamide by Solution Polymerization One ml of triethylamine and 1.36 grams of ethylene diamine were added to the dicarboxylic acid prepared above, which was allowed to-remain in solution. The  
 1 solution was heated at reflux for 90 minutes, then the solvent was distilled off at 90C under reduced pressure. The residue was heated at 180C at 2.0 mm Hg pressure for 1 hour, then at 210C at 0.2 mm pressure for 30 minutes. When cooled to room temperature, the product was a hard, tough polymer weighing 10.78  
 grams (93% yield). The polymer had an inherent viscosity (0.5% in m-cresol) of 0.26, a glass transition temperature of 103C, and a melting point of 240C. The polymer was melted to form a tough, flexible film.  
 EXAMPLE 3 The general procedure of Example 2 was followed except decamethylene diamine was employed in place of ethylene diamine in each preparation. The polymer obtained had an inherent viscosity (0.5% in m-cresol) of 0.56, a glass transition temperature of about 64C. and a melting point of C. A tough. flexible film was obtained by melting the polymer.  
 EXAMPLE 4 Preparation of Dicarboxylic Acid One ml of tri-n-propylamine and a solution of 1.62 grams 15 mmoles) of p-phenylenediamine in 20 ml of dimethylformamide was added to a stirred solution of 5.73 grams (30 mmoles) of nitrilotriacetic acid in 60 ml of dimethylformamide. After the reaction mixture had refluxed for 3 hours. 10 ml of toluene, which forms an azeotrope with water, was added. Refluxing was continued for 2 hours, during which time the theoretical amount of water was collected.  
 Preparation of Polyamide by Solution Polymerization A solution of 1.74 grams (l5 mmoles) of hexamethylene diamine in 10 ml of dimethylformamide was added to the solution prepared above containing the dicarboxylic acid. After the reaction mixture had refluxed for 2 hours, the solvent was distilled off at 60C under reduced pressure. The residue was heated at C at 0.5 mm Hg pressure for 2 hours, then at 230C for 45 minutes. When cooled to room temperature, the product was a hard, tough polymer weighing 7.60 grams (91% yield). The polymer had an inherent viscosity (0.5% in m-cresol) of 0.35 and a melting point in the range 315-319C. The polymer was melted and formed into a tough, flexible film.  
 EXAMPLE 5 Preparation of Polyester Nitrilotriacetic acid and p-phenylenediamine were reacted in accordance with the method described in Example 4 to produce 5 grams of the resultant dicarboxylic acid. The dicarboxylic acid was combined with 30 grams of hexamethylene glycol, 0.01 gram of triphenylphosphite, and 0.001 gram of antimony trioxide in a flask. The contents of the flask were maintained at 185C for 1 hour, during which time the solids melted and water was evolved. The pressure was then maintained at 1.0 mm Hg for 45 minutes as more water and excess hexamethylene glycol were removed. The reaction mass was then maintained at 250C at 0.5 mm Hg for 3 hours, after which it was comminuted. Nitrogen was slowly passed through the reaction mass during the entire polymerization period. The comminuted polymer was introduced into a 100 ml flask equipped with a stirrer. Polymerization was continued in the flask at 210C and at 0.5 mm Hg. The resultant polymer was film-forming, weighed 5.72 grams, had a melting point in the range 280290C, and had an inherent viscosity (0.5% in p-chlorophenol) of 0.32.  
 We claim: ing from 1 to 16 carbon atoms. 1. A polyester having recurring units of the&#39;formula 3. The polyester of claim 2 wherein R is methylene;  
 II II Ci C CH O n 2 C u -CE -ll l&#34;-l-l ,-!l N-R-C-O-R -O- 1 l CH C C CH wherein R is a phenylene radical or an alkylene radical 4. The polyester of claim 3 wherein R and R indehaving I to 6 carbon atoms, and R and R are organic pendently have the formula --(CH wherein n is an diradiCalS. integer from 1 to 10, or the formula --(CH ),,Z(CH  
 ) wherein Z is a phenylene radical and p and q are 2. The polyesterof claim 1 wherein R and R are aliindependently 0 1 2 or 3 phatic. aromatic or aliphatic-aromatic diradicals hav-