Dicarboxylic acids, polyamides from

Some of the most familiar reactions falling into the polycondensation class are those leading to polyamides derived from dicarboxylic acids and diamines, polyesters from glycols and dicarboxylic acids, polyurethanes from polyols and polyisocyanates, and polyureas from diamines and diisocyanates. Similar polymer formations utilizing bifunctional acid chlorides with polyols or polyamines also fall into this class. The condensations of aldehydes or ketones with a variety of active hydrogen compounds such as phenols and diamines are in this group. Some of the less familar polycondensation reactions include the formation of polyethers from bifunctional halogen compounds and the sodium salts of bis-phenols, and the addition of bis-thiols to diolefins under certain conditions. 

B. Polyamides with longer-chain dibasic acids. There are a number of p.(type I) based on longer-chain dicarboxylic acids derived from RR. Hexamethylenediamine with suberic acid forms polyamide 6,8 azeleic acid forms polyamide 6,9 and - sebacic acid polyamide 6,10. 

Nylon A class of synthetic fibres and plastics, polyamides. Manufactured by condensation polymerization of ct, oj-aminomonocarboxylic acids or of aliphatic diamines with aliphatic dicarboxylic acids. Also rormed specifically, e.g. from caprolactam. The different Nylons are identified by reference to the carbon numbers of the diacid and diamine (e.g. Nylon 66 is from hexamethylene diamine and adipic acid). Thermoplastic materials with high m.p., insolubility, toughness, impact resistance, low friction. Used in monofilaments, textiles, cables, insulation and in packing materials. U.S. production 1983 11 megatonnes. 

HOaQCHjlfiCOiH, CSH14O4. Important dicarboxylic acid obtained by oxidizing ricino-leic acid (from castor oil) also obtained by oxidation of cyclo-octene or cyclo-octadiene formerly obtained from cork. Used in the formation of alkyd resins and polyamides. Esters are used as plasticizers and heavy duty lubricants and oils. 

Diselosed is a proeess for the simultaneous production of dicarboxylic acids and diamines from a) polymers based on polyamides of dicarboxylic acids or their derivatives with diamines or b) compositions containing essentially such polymers. It involves treating these polymers or compounds with a base in alcoholic medium and subsequently converting the resulting dicarboxylate salts electrochemically into the corresponding dicarboxylic acids and bases. 

The use of oleochemicals in polymers has a long tradition. One can differentiate between the use as polymer materials, such as linseed oil and soybean oil as drying oils, polymer stabilizers and additives, such as epoxidized soybean oil as plasticizer, and building blocks for polymers, such as dicarboxylic acids for polyesters or polyamides (Table 4.2) [7]. Considering the total market for polymers of ca. 150 million tonnes in 1997 the share of oleochemical based products is relatively small - or, in other terms, the potential for these products is very high. Without doubt there is still a trend in the use of naturally derived materials for polymer applications, especially in niche markets. As an example, the demand for linseed oil for the production of linoleum has increased from 10000 tonnes in 1975 to 50 000 tonnes in 1998 (coming from 120000 tonnes in 1960 ) [8a]. Epoxidized soybean oil (ESO) as a plastic additive has a relatively stable market of ca. 100000 tonnes year-1 [8b]. 

Nylon-66 is made by the condensation polymerization of the dicarboxylic acid adipic acid, and 1,6-diaminohexane, an amine. (The number 66 comes from the fact that each of the two reactants contains six carbon atoms.) This reaction results in the formation of amide bonds between monomers, as shown in Figure 2.13. Condensation polymers that contain amide bonds are called nylons or polyamides. Condensation polymers that contain ester bonds are called polyesters. Polyesters result from the esterification of diacids and dialcohols. 

It has become the custom to name linear aliphatic polyamides according to the number of carbon atoms of the diamine component (first named) and of the dicarboxylic acid. Thus, the condensation polymer from hexamethylenedi-amine and adipic acid is called polyamide-6,6 (or Nylon-6,6), while the corresponding polymer from hexamethylenediamine and sebacoic acid is called polyamide-6,10 (Nylon-6,10). Polyamides resulting from the polycondensation of an aminocarboxylic acid or from ring-opening polymerization of lactams are indicated by a single number thus polyamide-6 (Nylon-6) is the polymer from c-aminocaproic acid or from e-caprolactam. 

Fully aromatic polyamides are synthesized by interfacial polycondensation of diamines and dicarboxylic acid dichlorides or by solution condensation at low temperature. For the synthesis of poly(p-benzamide)s the low-temperature polycondensation of 4-aminobenzoyl chloride hydrochloride is applicable in a mixture of N-methylpyrrolidone and calcium chloride as solvent. The rate of the reaction and molecular weight are influenced by many factors, like the purity of monomers and solvents, the mode of monomer addition, temperature, stirring velocity, and chain terminators. Also, the type and amount of the neutralization agents which react with the hydrochloric acid from the condensation reaction, play an important role. Suitable are, e.g., calcium hydroxide or calcium oxide. 

The synthesis of optically active polyamides, or nylons, is a growing area of interest. From 1980 to 1991 there have been many citations in Chemical Abstracts on this subject. For example, optically active polyamides have been prepared for the resolution of optical isomers. The polyamides are prepared from optically active amines or dicarboxylic acids. One polyamide was prepared from (-)-(ram-l,2-diaminocyclohexane and terephthaloyl chloride and was used to resolve 2,2 -dihydroxy-6,6 -dimethylbiphenyl [31]. These optically active polyamides can be used in chromatography applications to resolve other optically active compositions. 

The fiftieth anniversary of the announcement of nylon as the first synthetic organic textile fiber by the Du Pont Co. on October 27,1938 was celebrated as a significant event by the textile industry in 1988 (1,2). The announcement was the culmination of the fundamental research efforts of W. H. Carothers and his team at Du Pont (3). Carothers synthesized diamines from C2 to C18 in order for them to react with a variety of aliphatic dicarboxylic acids to make polyamides for evaluation as fibers (4—10). Alicyclic and aromatic diamines and dicarboxylic acids were also included. Nylon-6,6 was ultimately selected for scale-up and development because of its favorable melting point ( 260° C), best balance of properties, and lower manufacturing cost. The pilot plant for nylon-6,6 was completed in Wilmington, Delaware, in July, 1938, and a product was introduced on the market as Exton brisdes for Dr. West s toothbrushes (2). The first nylon filament plant was built in 1939 at Seaford, Delaware, and nylon stockings went on sale on October 24,1939 only to residents of Wilmington, and then nationally, on May 15, 1940 (2). 

A number of high melting point semiaromatic nylons, introduced in the 1990s, have lower moisture absorption and increased stiffness and strength. Apart from nylon-6 /6,T (copolymer of 6 and 6,T), the exact structure of these is usually proprietary and they are identified by trade names. Examples include Zytel HTN (Du Pont) Amodel, referred to as polyphthalamide or PPA (Amoco) and Aden (Mitsui Petrochemical). Properties for polyphthalamide are given in Table 2. A polyphthalamide has been defined by ASTM as "a polyamide in which the residues of terephthalic acid or isophthalic acid or a combination of the two comprise at least 60 molar percent of the dicarboxylic acid portion of the repeating structural units in the polymer chain" (18). 

Adipic acid [124-04-9] - [ALKYD RESINS] (Vol 2) - [DICARBOXYLIC ACIDS] (Vol 8) - [FOOD ADDITIVES] (Vol 11) - (ELECTROCHEMICALPROCESSDTG - ORGANIC] (Vol 9) -barrier polymers from [BARRIERPOLYMERS] (Vol 3) -from cyclohexane [HYDROCARBONS - C1-C6] (Vol 13) -from cyclohexane [HYDROCARBON OXIDATION] (Vol 13) -from cyclohexanol [CYCLOHEXANOL AND CYCLOHEXANONE] (Vol 7) -as food additive [FOOD ADDITIVES] (Vol 11) -nylon from [POLYAMIDES - FIBERS] (Vol 19) -nylon-6,6 from [POLYAMIDES - GENERAL] (Vol 19) -nylon-6,6 from [POLYAMIDES - PLASTICS] (Vol 19) -m polyester production [COMPOSITE MATERIALS - POLYMER-MATRIX - THERMOSETS] (Vol 7) -m polyester resins [POLYESTERS, UNSATURATED] (Vol 19) -soda preservatives [CARBONATED BEVERAGES] (Vol 5)... 

A variety of polyamides can be made by heating diamines with dicarboxylic acids. The most generally useful of these is nylon 66, the designation 66 arising from the fact that it is made from the. vA-carbon diamine, 1,6-hexanediamine, and a six-carbon diacid, hexanedioic acid ... 

The last-mentioned application was the aim of a patent206 dating from 1971. 4,8-Diamino-2,6-dioxabicyclo[3.3.0]octanes, endo-endo as well as endo-exo isomers, were used as starting materials for polyamides. First, the diamines 129 were transformed into their salts with various dicarboxylic acids, and these were polymerized to compounds 130 containing acylated amino moieties as monomeric building blocks (see Scheme 30). 

Furan-2,5-dicarboxylic add also has tremendous industrial potential, because it could replace oil-derived diadds such as adipic or terephthalic acid as monomers for polyesters and polyamides [98, 99]. This diadd can be synthesized by Pt-catalyzed oxidation with 02 of 5-hydroxymethylfurfural the latter is obtained by acid-catalyzed dehydration of D-frudose or frudosans (inulin) the latter, however, are too expensive as starting materials, and yields from glucose-based waste raw materials are no higher than 40%. Therefore, the potential attractive option of furan-2,5-dicarboxylic acid will develop only after an effident generation of 5-hydroxymethylfurfural from forestry waste materials has been developed. The same compound is also the starting material for the synthesis of other interesting chemicals obtained by oxidative processes, such as 5-hydroxymethylfuroic add, 5-formylfuran-2-carboxylic add and the 1,6-dialdehyde. 

The manufacture of the large variety of polyamides (commonly referred to as nylons) occurs through polycondensation of amino carboxylic acids (or functional derivatives of them, e.g. lactams) and from diamines and dicarboxylic acids. Labeling the amino groups with A and the carboxyl groups with B allows differentiation of the different chemical structures between the two types AB (from amino carboxylic acids) and AA-BB (from diamines and dicarboxylic acids). The number of C atoms in the monomers acts as a code number for the identification of the polyamides. The polycaprolactam manufactured from caprolactam (type AB) is then called polyamide 6 (PA 6). The number of carbon atoms in the diamine is given first for type AA-BB followed by the number of atoms in the dicarboxylic acid, e.g. PA 66 for polyhexamethylenedia-dipic amide from hexamethylenediamine and adipic acid. For copolymers the components are separated by a slash, e.g. PA 66/6 (90 10) is a copolymer composed of 90 parts PA 66 and 10 parts PA 6. 

Bis(hydroxymethyl) furan and 5-hydroxymethyl furfural (available from C6 sugars) have been oxidized to furan-2,5-dicarboxylic acid (44)- Linear polyesters, polyurethanes, and polyamides containing these monomers have been described in the literature (45-43) and have been made via condensation polymerization techniques including bulk, solution, and interfacial mixing procedures. Gandini (5,34) reviewed the poly condensation reactions up to 1986 and... 

The use of dicarbodiimides as monomers in polyaddition reactions have not as yet found wide utility. However, polymers containing carbodiimide groups are known, and further nucleophilic reactions of these polymers with numerous substrates are reported. Carbodiimides, generated in situ from isocyanates are used as catalyst in the formation of polyamides from diisocyanates and dicarboxylic acids. Also, homoleptic lanthanide amidinates, made from carbodiimides, exhibit high catalytic activity for the ring opening polymerization of e-caprolactone at room temperature. ... 

The generation of catalytic amounts of carbodiimides from diisocyanates is also applied in the manufacturing of polyamides from MDI and dicarboxylic acids and/or dicar-boxylic acid terminated prepolymers. These thermoplastic polyamides are produced continuously by reaction polymerization using a vented extruder to remove the carbon dioxide byproduct. Thermoplastic polyamides are manufactured today by the Dow Chemical Co., which purchased the Chemical Division of Upjohn in 1980. 

Carbodiimides are also used as catalysts in the formation of polyamides from dicarboxylic acids and diisocyanates. The carbodiimide catalyst is generated in situ from the diisocyanate using dimethylphospholene oxide as the catalyst. In this manner segmented thermoplastic poly(ether amides) and poly(ester amides) are obtained from the acid terminated monomers and diisocyanates by reaction polymerization processes. This reaction is best conducted in a vented extruder because carbon dioxide is the byproduct. 

The segmented polyamide elastomers are synthesized from MDI (4,4 -diisocyanato-diphenylmethane) and dicarboxylic acids and a carboxylic acid terminated aliphatic polyester, polycarbonate or polyether prepolymer with an average molecular weight of M = 500-5000. The dicarboxylic acids used as hard segment extenders are adipic and azelaic acid. Also, poly(ester amide) alloys are obtained using nylon-6,6 or polyesters (PEA/PBT). 

I became involved in carbodiimide chemistry in my research work on isocyanates at the former Donald S. Gilmore Research Laboratories of the Upjohn Company in North Haven, CT. Carbodiimides are readily synthesized from isocyanates using a phospholene oxide catalyst. This reaction can be conducted without a solvent, and the byproduct is carbon dioxide. We used this reaction in the manufacture of a liquid version of MDI (4,4 -diisocyanatodiphenylmethane), which today is sold in huge quantities worldwide. By reacting MDI with dicarboxylic acids in a vented extruder we manufactured a family of thermoplastic polyamide elastomers, which are sold today by the Dow Chemical Company. Also, N-sulfonylcarbodiimides were synthesized for the first time in our laboratories. They are the precursors of the antidiabetic sulfonamides, such as Upjohn s Tolbutamide (Orinase). Because of the close relationship of isocyanates with carbodiimides we studied many linear and cyclic carbodiimide reactions, especially their cycloaddition reactions. 

Another example of bulk (or melt) polymerization is the synthesis of polyamides through the direct interaction between a dicarboxylic acid and a diamine. Nylon 66, for example, can be produced from the reaction between hexamethylenediamine and adipic acid. In practice, it is preferable to ensure the existence of a 1 1 ratio of the two reactants by prior isolation of a 1 1 salt of the two. The overall procedure is summarized by the reaction scheme ... 

A number of organotin polyesters, polyamides, polythiols, polyethers, and polyaminoesters have been synthesized from dialkyltin halides with dicarboxylic acids, diols, diamines, dithiols, urea, thiourea, amino acids, and hydroxyl acids involving polycondensation reactions. These polymers have potential applications as thermostabilizers for PVC. 

---