Polyamides from acid chlorides

AB type aromatic polyamides, such as poly(benzamide) are prepared from acid chlorides or by the activation of the amino acids. These activation methods include... 

Aromatic polyamides are specialty products [182], used for high-performance fibers and composites, which are produced by solution or interfacial processes from acid chlorides and amines. 

It is also possible to prepare them from amino acids by the self-condensation reaction (3.12). The PAs (AABB) can be prepared from diamines and diacids by hydrolytic polymerization [see (3.12)]. The polyamides can also be prepared from other starting materials, such as esters, acid chlorides, isocyanates, silylated amines, and nitrils. The reactive acid chlorides are employed in the synthesis of wholly aromatic polyamides, such as poly(p-phenyleneterephthalamide) in (3.4). The molecular weight distribution (Mw/Mn) of these polymers follows the classical theory of molecular weight distribution and is nearly always in the region of 2. In some cases, such as PA-6,6, chain branching can take place and then the Mw/Mn ratio is higher. 

Acid chlorides are very reactive and have as a condensation product hydrochloric acid.4,7 9 This hydrochloric acid can form an amine salt with unreacted amine groups, which should be avoided. To prevent this happening, acid binders, which are more reactive than the amines, are added. Polyamidation can be earned out using a solution and with an interfacial method. With the interfacial method one has the choice between a stirred and an unstirred process. In an unstirred process, the polymerization is at the interface and a rope can be drawn from the interface,... 

Acid anhydride-diol reaction, 65 Acid anhydride-epoxy reaction, 85 Acid binders, 155, 157 Acid catalysis, of PET, 548-549 Acid-catalyzed hydrolysis of nylon-6, 567-568 of nylon-6,6, 568 Acid chloride, poly(p-benzamide) synthesis from, 188-189 Acid chloride-alcohol reaction, 75-77 Acid chloride-alkali metal diphenol salt interfacial reactions, 77 Acid chloride polymerization, of polyamides, 155-157 Acid chloride-terminated polyesters, reaction with hydroxy-terminated polyethers, 89 Acid-etch tests, 245 Acid number, 94 Acidolysis, 74 of nylon-6,6, 568... 

When the -OH of a carboxylic acid is replaced by an -NH2, the compound produced is an amide. Amides are neutral to mildly basic compounds. They can be made from acids, acid chlorides, acid anhydrides, and esters by reaction with ammonia or primary and secondary amines. The amide linkage is found in polyamide resins such as nylon. 

Diazocinyl-substituted phthalic anhydride 159 (R is inert, m = 0-3), prepared from 104 and the appropriately substituted acid chloride, underwent self or copolymerization to give polyamide-polyimides (83USP4391751). 

If one were to choose more reactive monomers, it would be possible to carry out polycondensations at considerably lower temperatures in solution. For example, consider the reaction of a diamine and a diacid to make a polyamide (nylon), a polymerization that requires relatively high temperatures (see Equation 9). A much faster reaction would occur between the diamine and a corresponding diacid chloride (see Equation 10). Both reactions would produce the same polymer, although the reaction conditions would be much different, and the byproduct HC1 from the acid chloride reaction would have to be carefully trapped. One technique for performing a polymerization such as that in Equation 10 is to dissolve the monomers in different, immiscible solvents, forcing the polymerization to occur only at the interface of the two solvents, a process called interfacial polymerization. Because of the high reactivity of an acid chloride, these reactions can be carried out at very low temperatures. This polymerization can be carried out rather dramatically in a beaker and is known as the nylon rope trick (see Section 4). 

Figure 5.21. Reaction schemes for the most common types of step-growth polymerization. Shown are (a/c) polyester formation, (b/d) polyamide formation, (e) polyamide formation through reaction of an acid chloride with a diamine, (f) transesterification involving a carboxylic acid ester and an alcohol, (g) polybenzimidazole formation through condensation of a dicarboxyhc add and aromatic tetramines, and (h) polyimide formation from the reaction of dianhydrides and diamines.

Aminocyclopropanes were easily acylated by acid chlorides, isocyanates or isothiocyanates (e.g. Refs 3, 24, 27, 36, 71, 80, 82, 125, 178, 179, 184, 224). Polyureas, polyurethanes or polyamides have been prepared from 1,2-diaminocyclopropane Reduction of the carbonyl group in 423 by lithium aluminum hydride worked quite well for tertiary amides 5,473.495. longer reaction times effected a ring-opening in the case of a secondary amide (423, R = H) (LiAlH4 reduction of secondary... 

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. 

Fig. 9. Schematic diagram of concentrations in an interfacial polyamidation. Amine groups (A) are in the water phase. Acid chloride (C) and amine groups at partition equilibrium (B) are in the organic phase. P and the dotted lines show the relation of the reactive groups when the first incremental layer of polymer forms (from ref. 6).

Reaction of Acid Chlorides. Low-temperature polycondensation of diamines and diacid chlorides is an important route for preparing high-melting polyamides such as aromatic polyamides, which decompose or cross-link if prepared by high-temperature melt routes. The reaction may involve an interfacial reaction between the diacid chloride in a water-immiscible solvent with an aqueous diamine solution, or the reaction may be carried out in a homogeneous solution. The presence of a base is usually needed to remove HCl so that polymerization is complete. With weakly basic aromatic diamines, an acid acceptor is not always needed because HCl can be evaporated from the reaction mixture. The general reaction is given by... 

Polyamides have been synthesized under microwave conditions from both fa-amino acids and Nylon-salt-type monomers, and polyimides have been obtained from salt monomers comprising aliphatic diamines and pyromellitic acid or its diethyl ester or derivatives of pyromellitic acid chlorides and aromatic diamines in the presence of a small amount of an organic solvent [1]. 

Improvement of Water Permeability (UTC-70L) In our past experiments of various polyamide composite membranes, introduction of end acids is preferable to obtain better water permeability and decrease of end amines is preferable to obtain better tolerance to chloride. From the view point, we tried to improve water permeability of UTC-70. Our strategy for introduction of end acids and decrease of end amines is an improvement of acid chlorides reactivity by using catalyst for in-situ interfacial polycondensation. Thus, we found common catalysts for acylation worked effectively as we had expected, and water permeability of UTC-70 were increased without severe decrease of membrane selectivity. This type of membrane are commercialized as "UTC-70L", and membrane performance is shown Figure 7. 

Nomex is an aromatic polyamide (aramid) prepared from the polymerization of 1,3-benzenediamine and the acid chloride of 1,3-benzenedicarboxylic acid ... 

In a similar way, the synthesis of aromatic polyamides from aromatic diamines m-phenylenediamine, p-phenylenediamine, bis(4-aminophenyl)methane, and bis(4-aminophenyl)ether and dicarboxylic acids such as isophthalic and tereph-thalic acid was performed in a household microwave oven [72]. The polycondensation was carried out in an JV-methyl-2-pyrrolidone (NMP) solution in the presence of triphenyl phosphite (TPP), pyridine, and lithium chloride as condensing agents to produce a series of polyamides with moderate inherent viscosities of 0.21-0.92 dL/g within 30-50 s. However, no marked differences in molecular weight distribution and inherent viscosities between the polyamides produced by conventional (60 s, 220 °C) and microwave methods were found [72]. 

Reaction of a dicarboxylic acid, or one of its derivatives, with a diamine leads to a linear polyamide through a condensation reaction. Commercially, nylon 6-6 (so called because each monomer has six carbons) is made from adipic acid and hexam-ethylenediamine. In this experiment, you will use the add chloride instead of adipic acid. The acid chloride is dissolved in cyclohexane, and this is added carefully to hexamethylenediamine dissolved in water. These liquids do not mix, so two layers will form. The polymer can then be drawn out continuously to form a long strand... 

Hattori T, Kagawa K, Kakimoto M and Imai Y (1993) Novel 2-step synthesis of poly(benzo-thiazoles) via new precursor polyamides from 2,5-bis[(cyanoethyl)thio]-l,4-phenylenediamine and aromatic dicarboxylic-acid chlorides. Macromolecules 26 4089-4093. 

Poly(imidazole)amides, a new class of heteroaromatic polyamides, were prepared from the polymerization of amino acids and acid chlorides to yield low to moderate molecular weight polymers. These materials are thermally stable in excess of 300°C, under nitrogen atmosphere Presently, we are investigating methods to increase molecular weights of these polymers as well as preparing new AB monomers, as shown below. 

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