Dechlorination of N-chloro poly(hexamethylene adipamide) and N-chloro poly(ε-caprolactam) products to the corresponding polyamides

A rapid dechlorination method of N-chloro poly(hexamethylene adipamide) and N-chloro poly(ε-caprolactam) to the corresponding polyamides was studied. This method can be used for molecular weight determinations of N-chloro polyamides by viscosimetric measurements. The dechlorination was achieved in formic acid solution by the reaction of N-chloro polyamides with trialkyl phosphites. The reaction was exothermic and vigorous and was applied to a series of products of various degrees of N-chlorination covering the range of 0–100%. No N—Cl was detected by iodimetric titration of the dechlorination products. The dechlorination of N-chloro polyamides was demonstrated by infrared (IR) spectroscopy. No significant molecular weight reduction except that taking place in the N-chlorination reaction of poly(hexamethylene adipamide) was observed.     

Photoconductivity of poly(hexamethylene adipamide)

Photocurrents induced by pulsed ultraviolet light in polyhexamethylene adipamide (nylon-66) have been studied. Two transient photocurrents are observed for light wavelenghts shorter than 3000 Å;. The first one is weakly field and temperature dependent and has been ascribed to electron photoinjection. On the whole, the time dependence of the two photoresponses suggests the possible formation of a space charge in the material.     

Structure evolution of α′‐phase poly(lactic acid)

Poly(lactic acid) films consisting of α′‐forms were prepared and uniaxially drawn. The effects of the draw rate at temperatures above the glass transition temperature on chain conformation, degree of crystallinity, and crystalline phase transformation were investigated by a combination of vibrational spectroscopy (infrared and Raman), differential scanning calorimetry, and wide‐angle X‐ray diffraction (WAXD). It was established that the α′‐crystal's phase of poly(lactic acid) films does not transform into either an α or β crystals on uniaxial drawing at a fixed draw ratio of 4. However, the degree of crystallinity was significantly increased on deformation. The structural change as a function of deformation also promotes an increase in the strain‐induced enthalpic relaxation endothermic peak appearing near the glass transition region. While the overall changes in physical properties can be attributed to the changes in the degree of crystallinity as a function of strain rate, polarized Raman spectra, and WAXD clearly illustrated changes and the differences in the amorphous and crystalline orientation as a function of processing conditions. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1446–1454, 2011     

Effect of tin tetrachloride on thermal decompositions of α,α′-azobisisobutyronitrile and dimethyl α,α′-azobisisobutyrate

Thermal decomposition of α,α′-azobisisobutyronitrile (AIBN) and dimethyl α,α′-azobisisobutyrate (MAIB) in the presence of a large amount of tin tetrachloride was investigated to determine the effect of complex formation on the decomposition rates and yields of the recombination products. The addition of tin tetrachloride significantly increased the decomposition rates; the observed first-order rate constant increased by factors of 4.5 and 17 at molar ratios of [SnCl₄]/[AIBN] = 21.65 and [SnCl₄]/[MAIB] = 19.53, respectively. It was found that the decomposition of these azo compounds was also accelerated by the addition of a comparable amount of donor solvent such as ethyl acetate or propionitrile to tin tetrachloride and that the enhancement in rate was accounted for by a larger frequency factor in the Arrhenius equation. Furthermore, the addition of tin tetrachloride seemed to suppress the formation of recombination products, tetramethyl succinonitrile and dimethyl tetramethylsuccinate, of the radicals produced by decomposition.     

γ Radiolysis of poly(4,4′-isopropylidene diphenylene sebacate)

Poly-(4,4′-isopropylidene diphenylene sebacate) (PIDPS), a condensation product of bisphenol-A and sebacic acid, was irradiated with ⁶⁰Co γ rays. Viscosity, end-group analysis, and IR spectral measurement techniques were used to study the chemical changes occurring during γ radiolysis. It is observed that PIDPS undergoes random chain scission owing to weak links which may be present or be incorporated by the oxygen from air. The G value of random chain scission is estimated to be 9, whereas the enthalpy of fusion is found to be 6.2 kcal/mol repeat unit of PIDPS.     

5-(α-Fluorovinyl)tryptamines and 5-(α-Fluorovinyl)-3-(N-methyl-1′,2′,5′,6′,-tetrahydropyridin-3′- and -4′-yl)indoles—5-(α-Fluorovinyl)tryptamines

5-(α-Fluorovinyl)tryptamines 4a, 4b and 5-(α-fluorovinyl)-3-(N-methyl-1′,2′,5′,6′-tetrahydropyridin-3′- and -4′-yl) indoles 5a, 5b were synthesized using 5-(α-fluorovinyl)indole ( 7 ). The target compounds are bioisosteres of 5-carboxyamido substituted tryptamines and their tetrahydropyridyl analogs.     

Monolayer behaviors of poly(hexamethylene adipamide) at the air/water interface

Monolayer films on the neutral water substrate were obtained by spreadingN-trifluoroacetic anhydride (NTF)-modified nylon 66 or nylon 612 in chloroform solutions. Alternatively, monolayer films were obtained by spreading from nylon 66 solutions in the 31 mixture of benzene (B) and phenol (P). The temperatures studied are 10.3°, 14.7°C, and 19.4°C. The isothermss of surface pressure (), and surface moment () against surface area per residue (A) were determined. The -A isotherms of the NTF-modified nylon 66/chloroform and the nylon 66/BP were found to be an expanded type, while that of NTF-modified nylon 612/chloroform was of a condensed type. The NTF-modified nylon 66/chloroform solutions could yield well-spread films even higher concentrations than nylon 66/BP solutions. In the -A isotherms at 10.3° and 14.7°C, the surface moments are constant at 143 mD/residue for NTF-modified nylon 66/chloroform, and 340 mD/residue for nylon 66/BP until the surface area reaches where the -A isotherms show a transition point. After the transition point, the surface moments for both systems drop steadily. However, the surface moment at 19.4°C shows a maximum at the transition point. Possible configuration of the nylon 66 residue in monolayer is discussed.     

Synthesis of vinyl graft copolymers of poly(hexamethylene adipamide) and poly(m-phenylene isophthalamide)

Nylon 66 [poly(hexamethylene adipamide)] and Nomex [poly(m-phenylene isophthalamide)] were metalated by using solutions of sodium in liquid ammonia. Metalation of the Nomex polymer was also carried out by using sodium naphthalene in tetrahydrofuran. The metalated polymers were then reacted with acrylonitrile monomer to yield the corresponding anionic graft copolymers. The heterogeneous nature of these reactions is discussed in relation to the structure of the graft copolymers.     

Synthesis of α,α′‐Bis(Substituted Benzylidene)Cycloalkanones Catalyzed by Amino‐Functionalized Ionic Liquid

Condensation of aromatic aldehydes with cyclopentanone and cyclohexanone using amino‐functionalized ionic liquid, 1‐aminoethyl‐3‐methyl tetrafluoroborate as solvent and catalyst was successfully performed for preparation of α,α′‐bis(substituted benzylidene)cycloalkanones. The catalyst can be recovered and reused for at least three times without apparently lose of activity. The process is simple, environmentally benign and proceeds in excellent yields.     

Synthesis of poly(γ-methoxypropylmethylsilylene) and poly(γ-methoxypropylmethylsilylene-co-di-n-hexylsilylene)

The synthesis of γ;-methoxypropylmethyldichlorosilane, and its subsequent polymerization and copolymerization with di;-n;-hexyldichlorosilane through the reductive coupling with sodium has been accomplished. The resulting polymers contain methyl ether side groups that allow further synthetic transformations on the polysilane backbone. For poly (γ;-methoxypropylmethylsilylene) these groups impart solubility characteristics different than typical alkyl and aryl substituted polysilanes. These new polymers and copolymers have been characterized by GPC and ¹H-, ¹³C-, and ²⁹Si-NMR. © 1994 John Wiley & Sons, Inc.     

Nonreductive Enantioselective Ring Opening of N-(Methylsulfonyl)dicarboximides with Diisopropoxytitanium α,α,α′,α′-Tetraaryl-1,3-dioxolane-4,5-dimethanolate

The bicyclic and tricyclic meso-N-(methylsulfonyl)dicarboximides 1a–f are converted enantioselectively to isopropyl [(sulfonamido)carbonyl]-carboxylates 2a–f by diisopropoxytitanium TADDOLate (75–92% yield; see Scheme 3). The enantiomer ratios of the products are between 86:14 and 97:3, and recrystallization from CH₂Cl₂/hexane leads to enantiomerically pure sulfonamido esters 2 (Scheme 3). The enantioselectivity shows a linear relationship with the enantiomer excess of the TADDOL employed (Fig.3). Reduction of the ester and carboxamide groups (LiAlH₄) and additional reductive cleavage of the sulfonamido group (Red-Al) in the products 2 of imide-ring opening gives hydroxy-sulfonamides 3 and amino alcohols 4 , respectively (Scheme 4). The absolute configuration of the sulfonamido esters 2 is determined by chemical correlation (with 2a,b ; Scheme 6), by the X-ray analysis of the camphanate of 3e (Fig. 1), and by comparative ¹⁹F-NMR analysis of the Mosher esters of the hydroxy-sulfonamides 3 (Table 1). A general proposal for the assignment of the absolute configuration of primary alcohols and amines of Formula HXCH₂CHR¹R², X = O, NH, is suggested (see 11 in Table 1). It follows from the assignment of configuration of 2 that the Re carbonyl group of the original imide 1 is converted to an isopropyl ester group. This result is compatible with a rule previously put forward for the stereochemical course of reactions involving titanium TADDOLate activated chelating electrophiles ( 12 in Scheme 7). A tentative mechanistic model is proposed ( 13 and 14 in Scheme 7).     

Solid-state photopolymerization of α,α′-bis(4-acetoxy-3-methoxybenzylidene)-p-benzenediacetonitrile

One crystalline form of α,α′-bis(4-acetoxy-3-methoxybenzylidene)-p-benzenediacetonitrile is photopolymerized by a four-center reaction to give a polymer containing alternating benzene and cyclobutane rings. The polymer is highly crystalline and insoluble in most solvents. Location of groups around the cyclobutane ring is deduced from the products obtained on thermal decomposition. Chain contained benzene rings are located in positions 1 and 3; aromatic groups alternate sides of the cyclobutane ring. Special characterization and quantum yield of the polymerization are reported, as well as polymer solution viscosity and alkaline depolymerization of the polymer.     

A novel synthesis of α-hydroxy- and α,α′-dihydroxyketone from α-iodo and α,α′-diiodo ketone using photoirradiation

A novel reaction of α-iodo ketone (α-iodocycloalkanone, α-iodo-β-alkoxy ester, and α-iodoacyclicketone) with irradiation under a high-pressure mercury lamp gave the corresponding α-hydroxyketone in good yields. In the case of α,α′-diiodo ketone, α,α′-dihydroxyketone which little has been reported until now was obtained. This reaction affords a new, clean and convenient synthetic method for α-hydroxy- and α,α′-dihydroxyketone.     

Nuclear magnetic relaxation of α-13C nuclei of helical poly(γ-hexyl-L-glutamate) and poly(γ-benzyl-L-glutamate)

Spin-lattice relaxation times (T₁), spin-spin relaxation times (T₂), and nuclear Overhauser enhancements (NOE), at 75.5 MHz are reported for α-¹³C nuclei of poly (γ-benzyl-L -glutamate) in deuterated dimethylformamide at 60°C and of poly(γ-hexyl-L -glutamate) in cyclohexanone at 48 and 79°C. It is shown that for molecular weights above 10⁵, the polypeptides cannot be considered as essentially rigid helices with internal librational motions; additional backbone flexing motions contribute to the relaxation behavior.     

Polyesters from α,α′-dicarbomethoxy-α,α′-diphenyl-p-xylylene and the synthesis and properties of a new quinodimethane

A film forming polyester was obtained from the title compound and 1,4-butanediol. In addition oxidation of the title compound gave rise to 7,8-dicarbomethoxy-7,8-diphenylquinodimethane as a mixture of Z and E isomers. The ¹H-NMR and the electronic characterization of this polymer are discussed. The quinodimethane will undergo 1,6-nucleophilic addition to form an aromatic compound.     

Polyenaminoesters from α,α′-bis(carbomethoxy)diacetylbenzenes and phenylene diamines

Polyenaminoesters are prepared by condensation of α,α′-bis(carbomethoxy)diacetylbenzenes with phenylene diamines in the presence of N,N-dimethylaniline hydrochloride. Thermogravimetric analysis allowed the determination of the optimum temperature at which to conduct cyclization of the polymers to form thermally stable polypyridoquinolones. The structures of the polymers were assigned by spectroscopic comparisons with appropriate model compounds.