Hydroquinone Decorated with Alkyne,Quaternary Ammonium,and Hydrophobic Motifs to Mitigate Corrosion of X-60 Mild Steel in 15 wt.% HCl

1-(6-Bromohexyloxy)-4-propargyloxybenzene upon quaternization with 3-dimethylamino-1-propanol and N,N-dimethyldodecylamine produced two new inhibitor molecules: N-[6-(4-Propargyloxyphenoxy)hexyl]-N,N-dimethyl-N-(3-hydroxypropyl)ammonium bromide (PHAB) and N-[6-(4-Propargyloxyphenoxy)hexyl]-N,N-dimethyl-N-dodecylammonium bromide (PDAB), respectively, in excellent yields. The inhibitor molecules were characterized by elemental analysis, Fourier transform infrared spectroscopy, ¹H NMR, and ¹³C NMR spectroscopy. The inhibitors were evaluated for X-60 mild steel corrosion in 15 wt.% HCl using different electrochemical and gravimetric techniques. The potentiodynamic polarization confirms both the inhibitors as mixed-type corrosion inhibitors. A low concentration (15 ppm) of PDAB has demonstrated excellent corrosion inhibition efficiencies of 97%, 98%, and 86% at 25 °C, 50 °C, and 70 °C, respectively, for 24 h exposure time. SEM and EDX spectra reveal that the adsorptions of corrosion inhibitors on X-60 mild steel create a protective film that serves as a barrier to mitigate the corrosion process. The X-ray photoelectron spectroscopy confirmed the chemical interaction between the corrosion inhibitors and mild steel, which was predicted by the Langmuir adsorption model. Assembly of inhibitive motifs of the alkyne, π-electron-rich aromatic, quaternary ammonium and C₁₂ alkyl chain hydrophobe in PDAB has augmented its inhibiting action.     

Dissociation energy of N-H bonds in diatomic aromatic amines

The dissociation energies of N-H bonds (D, kJ/mol) were calculated by the intersecting parabolas method using the kinetic data for the following aromatic diamines: para-phenylenediamine (359.8), N,N′-dimethyl-para-phenylenediamine (348.9), N-dimethyl-N′-methyl-para-phenylenediamine (342.4), N,N′-diphenyl-para-phenylenediamine (352.8), N,N′-diphenylethylenediamine (372.7), N,N′-diheptylethylenediamine (373.3), N,N′-di-(4,4′-ethoxyphenyl)ethylenediamine (363.3), N,N′-di-(4,4′-diisopropylphenyl)-para-phenylenediamine (344.6), 4-{[dimethyl(4-phenylamino)phenoxy)silyl]oxy}-N-phenylaniline (353.4), N,N′-di-β-naphthyl-para-phenylenediamine (354.6), N,N′-di-β-naphthoxy-para-phenylenediamine (353.7), 1,1′-dinaphthyl-2,2′-bis-N,N′-phenyldiamine (372.9), 1,1′-dinaphthyl-2,2′-bis-N,N′-β-naphthyldiamine (384.2), and 2,6-bis[(1E)-1-(2-phenylhydrazin-1-ylidene)ethyl]pyridine (367.9). Individual dissociation energies for the two N-H bonds were determined in N-phenyl-N′-isopropyl-para-phenylenediamine: D(PhN-H) = 352.5 and D(Me₂CHN-H) = 348.7 kJ/mol.     

Allgemeiner Zugang zu Polyaminen mit Ethan-1,2-diamin-Einheiten: Synthese von nicht natürlich vorkommenden homologen und isomeren N1,4-Di(4-cumaroyl)sperminen

█tl="American"█The synthesis of the three N,N′-di(4-coumaroyl)tetramines, i.e., of (E,E)-N-{3-[(2-aminoethyl)amino]propyl}-3,3′-bis(4-hydroxyphenyl)-N,N′-(ethane-1,2-diyl)bis[prop-2-enamide] ( 1a ), (E,E)-N-{4-[(2-aminoethyl)amino]butyl}-3,3′-bis(4-hydroxyphenyl)-N,N′-(ethane-1,2-diyl)bis[prop-2-enamide] ( 1b ), and (E,E)-N-{6-[(2-aminoethyl)amino]hexyl}-3,3′-bis(4-hydroxyphenyl)-N,N′-(ethane-1,2-diyl)bis[prop-2-enamide] ( 1c ), is described. It proceeds through stepwise construction of the symmetric polyamine backbone including protection and deprotection steps of the amino functions. Their behavior on TLC in comparison with that of 1,4-di(4-coumaroyl)spermine (=(E,E)-N-{4-[(3-aminopropyl)amino]butyl}-3,3′-bis(4-hydroxyphenyl)-N,N′-(propane-1,3-diyl)bis[prop-2-enamide]; 2 ) is discussed.     

New synthetic route to alternating copoly(aromatic ester–aliphatic amide)s

The preparation of three novel alternating copoly(aromatic ester–aliphatic amide)s containing the same ordered amide–amide–ester–ester (AAEE), the same para-disubstituted phenyl, and the different long methylene chain structure were described. 1,1′-(Adipoyl)bisbenzotriazole (AdBBT), 1,1′-(suberoyl)bisbenzotriazole (SuBBT), and 1,1′-(sebacoyl)bisbenzotriazole (SeBBT) were synthesized. These diacylbenzotriazoles were preferred to aminoethanol at the amino group because of the selective N-acylation of active acylamide of benzotriazole in excellent yield at room temperature to give diol monomers such as N,N′-bis(2-hydroxyethyl)adipic amide (HEAdA), N,N′-Bis(2-hydroxyethyl)subaric amide (HESuA), and N,N′-bis(2-hydroxyethyl)sebacic amide (HESeA). Polycondensation of 1,1′-(teraphthaloyl)bisbenzotrizole (tPBT) with HEAdA, HESuA, and HESeA gave the corresponding alternating copoly(aromatic ester–aliphatic amide)s: P(tPE–AdA), P(tPE–SuA), and P(tPE–SeA), respectively. The alternating copoly(aromatic ester–aliphatic amide)s were characterized by ¹H-NMR spectra. The resulting polymers have two different chain units; one is chain unit of poly(ethylene terephthalate) and the other is a chain unit of polyamide-2,6, polyamide-2,8, and polyamide-2,10; both are linked via a C? N bond.     

Applications of micelle and microemulsion systems containing aminated surfactants synthesized from ricinoleic acid as carbon-steel corrosion inhibitors

The high affinity of surfactant molecules to adsorb onto interfaces is responsible for their applications in several interfacial systems. For this reason, surfactants can be used as good corrosion inhibitors in metallic surfaces. The main objective of this work was to examine the anticorrosion ability of three novel surfactant molecules synthesized from ricinoleic acid, a castor oil derivative. The surfactants are: sodium 12-N,N-diethylamino-9-octadecenoate (AR1S), sodium 12-N,N-diethylamino-9,10-dihydroxy-octadecanoate (AE2S) and sodium 12-N,N-diethylamino-9-octadecanoate (AE1S). Their ability to inhibit corrosion in AISI 1010 carbon-steel has been investigated by preparing specific micellar solutions and microemulsion systems. Adsorption phenomena have been electrochemically studied with the Frumkin model, indicating that the surfactant solutions tested can inhibit corrosion with levels as high as 95%. On the other hand, the microemulsion systems, although featuring relatively lower performance, are advantageous in that they are able to dissolve more active matter. These results are useful as a basis to propose and study particular applications such as the transport of oil in petrochemical industries.     

The synthesis of azahomotryptophane derivatives. The transformation of N-trifluoroacetyl-5-bromo-4-oxonorvaline methyl ester into 4-(imidazo[1,2-a]azinyl-3)-4-oxohomoalanine derivatives

Azatryptophane homologues, 4-(imidazo[1,2-a]pyridinyl-3)- 9a-9f and 4-(imidazo[1,2-a]pyrimidinyl-3)-4-oxohomoalanine derivatives 9g-91 , were prepared from N,N-dimethyl-N′-(pyridinyl-2)- 6a-6f and N,N-dimethyl-N-(pyriniidinyl-2)formamidines 6g-6i , and (S)-N-trifluoroacetyl-5-bromo-4-oxonorvaline methyl ester ( 2 ) and its (R,S)-isomer.     

Synthesis and characterization of model compounds for carbazole-substituted N-acylated linear polyethylenimine (PEI). Synthesis and 1H-NMR spectra of N-acylated diethylamine and N,N′-dimethyl-1,2-ethanediamine containing 9-carbazolylacetyl, (R,S)- or (R)-2-(9-carbazolyl)propanoyl groups

The synthesis of N,N-diethyl-9-carbazolylacetamide ( 6 ), (R,S)- and (R)-N,N-diethyl-2-(9-carbazolyl)propanamide ( 7 ), N,N′-dimethyl-N,N′-di-(9-carbazolylacetyl)-1,2-ethanediamine ( 11 ), and (R)-N,N′-dimethyl-N,N′-di[2-(9-carbazolyl)propanoyl]-1,2-ethanediamine ( 13 ) is reported. The racemic compound, (R,S)-2-(9-carbazolyl)propanoic acid ( 2 ), was resolved by partial crystallization of the diastereomeric salts formed between 2 and (+)-α-methylbenzylamine. The ¹H-NMR spectra of 6 and 7 showed magnetic nonequivalence of the chemically equivalent protons of the methyl and methylene groups in 6 and 7 due to partial double bond character of the amide bond. The upfield resonances corresponding to the two sets of methyl and methylene protons were assigned by the aromatic solvent-induced shift (ASIS) method to the protons anti to the carbonyl oxygen in the conformation of amide bond in 6 and 7 . The ¹H-NMR spectra of 11 and (R)- 13 were used to determine the population of anti-anti, anti-syn (syn-anti) and syn-syn conformers in the structures of these dimer model compounds; the relative conformer populations were 0.45:0.47:0.08 and 0.28±0.02:0.29±0.01:0.43±0.01 in 11 and (R)- 13 .     

Synthesis of A-B-A Type Block Copolymer of Methyl Methacrylate and Styrene by Living Free-Radical Polymerization†

Abstract

A newly synthesized iniferter, N,N′-dimethyl-N,N′-bis(phenethyl)-thiuram disulfide, has been used in the free-radical living polymerization of styrene by a photochemical method. The low molecular weight (M _w = 6000) difunctionalized polystyrene was used as a macroiniferter to photopolymerize methyl methacrylate, and was fractionated to obtain an A-B-A type block copolymer containing two poly(methyl methacrylate) units and one polystyrene unit in each block. The glass transition temperature, thermal stability, and ¹³C NMR of the block copolymer are discussed.     

Synthesis and characterization of new ointment-like poly(ortho esters)

Ointment-like poly(ortho esters) were synthesized for the first time from the reaction of 3,9-bis(methylene)-2,4,8,10-tetraoxaspiro[5. 5] undecane with poly(ethylene glycol)-400, N,N-bis(2-hydroxyethyl)-n-hexadecylamine and N,N-bis(2-hydroxyethyl) palmitamide, respectively. The obtained polymers were characterized by 1H NMR spectra, 13C NMR spectra, elemental analyses, light scattering, and measurements of intrinsic viscosity. The influence of catalyst on the intrinsic viscosity of polymers was investigated. The 9-[(1,3-dihydroxy-2-propoxy) methyl] guanine controlled release profiles of hydrophobic ointment-like polymers such as polymer P_II in vitro were also discussed.     

The cyclization of N,N′-bis[2-(dialkoxy)ethyl]-p-xylene-α,α′-diamine dihydrochloride to pyrido[3,4-g]isoquinoline and 3,8-phenanthroline

The ring closure of N,N′-bis[2-(dialkoxy)ethyl]-p-xylene-α,α′-diamine dihydrochloride in fuming sulfuric acid has been investigated and the cyclization products have been identified as the linear pyrido[3,4-g]isoquinoline as well as the previously reported angular 3,8-phenanthroline.     

Synthesis and characterization of soluble aromatic polyurea-amides from new N,N′--dimethyl-N,N′-bis(aminophenyl)ureas and aromatic dicarboxylic acid chlorides

Aromatic polyurea-amides having inherent viscosities of 0.36–0.67 dL/g were synthesized by the low temperature solution polycondensation of new N,N′-dimethyl-N,N′-bis(aminophenyl)ureas with various aromatic dicarboxylic acid chlorides. All the polymers were amorphous, and most of them were soluble in a variety of organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide (DMAc), m-cresol, and pyridine. Some of the polymers could be cast from the DMAc solutions into transparent and flexible films having good tensile properties. The glass transition temperatures of the polyurea-amides obtained from the bis(4-aminophenyl)-substituted ureas were 244–272°C. The temperatures of 10% weight loss under nitrogen of the polymers were in the range of 430 and 480°C. © 1995 John Wiley & Sons, Inc.     

Modification of magnesium silicate with 15(2)-methyl ester of 13(1),17(3)-diamino-<Emphasis Type="Italic">N,N</Emphasis>′-bis(2-hydroxyethyl)-13(1),17(3)-dioxochlorin <Emphasis Type="Italic">e</Emphasis><Subscript>6</Subscript>

Magnesium silicates modified with 15(2)-methyl ester of 13(1),17(3)-diamino-N,N′-bis(2-hydroxyethyl)-13(1),17(3)-dioxochlorin e ₆ have been synthesized by heat treatment in water containing small fraction of ethanol. X-ray phase analysis, differential scanning calorimetry, thermogravimetry, and UV-Vis spectroscopy studies have shown that the synthesized samples contain individual molecules of 15(2)-methyl ester of 13(1),17(3)-diamino-N,N′-bis(2-hydroxyethyl)-13(1),17(3)-dioxochlorin e ₆ held on the inorganic substrate surface by electrostatic interaction and hydrogen bonding.     

Use of an amide-type corrosion inhibitor synthesized from the coffee bagasse oil on the corrosion of Cu in NaCl

An amide, namely N-[2-[(2-hydroxyethyl) amino] ethyl]-amide, extracted from the fatty acids contained in the coffee bagasse, has been investigated as a possible green corrosion inhibitor for copper in 3.5% NaCl by using potentiodynamic polarization curves and electrochemical impedance spectroscopy measurements. Results were complemented by detailed scanning electronic microscopy, FTIR and gas chromatography studies. Results have shown that N-[2-[(2-hydroxyethyl) amino] ethyl]-amide is a good, mixed type of corrosion inhibitor, with an efficiency that increases with its concentration but it decreases with a rise in the temperature. It adsorbs chemically onto the copper surface by following a Langmuir type of adsorption isotherm.     

Non-Heme FeII Diastereomeric Complexes Bearing a Hexadentate Ligand: Unexpected Consequences for the Spin State and Catalytic Oxidation Properties

The reactivity and selectivity of non-heme Fe^II complexes as oxidation catalysts can be substantially modified by alteration of the ligand backbone or introduction of various substituents. In comparison with the hexadentate ligand N,N,N′,N′-tetrakis(pyridin-2-ylmethyl)ethane-1,2-diamine (TPEN), N,N′-bis[1-(pyridin-2-yl)ethyl]-N,N′-bis(pyridin-2-ylmethyl)ethane-1,2-diamine (_2MeL₆²) has a methyl group on two of the four picolyl positions. Fe^II complexation by _2MeL₆² yields two diastereomeric complexes with very similar structures, which only differ in the axial/equatorial positions occupied by the methylated pyridyl groups. In solution, these two isomers exhibit different magnetic behaviors. Whereas one isomer exhibits temperature-dependent spin-state conversion between the S=0 and S=2 states, the other is more reluctant towards this spin-state equilibrium and is essentially diamagnetic at room temperature. Their catalytic properties for the oxidation of anisole by H₂O₂ are very different and correlate with their magnetic properties, which reflect their lability/inertness. These different properties most likely depend on the different steric constraints of the methylated pyridyl groups in the two complexes.     

Flocculation Properties of Polyelectrolytes Based on 2-(N,N-Dimethyl-N-Benzylammonio)ethyl Methacrylate Chloride

Precipitation of a model kaolin suspension and dehydration of the excess active sludge were studied as influenced by copolymers of 2-(N,N-dimethyl-N-benzylammonio)ethyl methacrylate chloride and its copolymers with acrylamide and 2-(N,N,N-trimethylammonio)ethyl methacrylate methyl sulfate.     

Preparation of polyhydrouracils and polyiminoimidazolidinones

Polyhydrouracils and polyiminoimidazolidinones were prepared by ring formation along the chain of appropriately substituted polyureas. Cyclization of 2-carbomethoxy-ethyl-substituted polyureas in a polyphosphoric acid medium gave the polyhydrouracils. The polyurea precursors were prepared from N,N′-bis(2-carbomethoxyethyl)-1,6-hexanediamine and N,N′-di(2-carbomethoxyethyl)-1,4-cyclohexanebis(methylamine) with methylenebis(4-phenyl isocyanate), 2,4-toluene diisocyanate, and 3,3′-dimethoxy-4,4′-biphenylene diisocyanate. These polyureas were soluble in m-cresol, dimethylformamide, and chloroform, had inherent viscosities of up to 0.8, and could be cast into tough films. The polyhydrouracils had similar physical properties and could also be cast into films. The polyhydrouracils melted at temperatures 100–150°C higher than their polyurea precursors. Polyiminoimidazolidinones were prepared by cyclization of α-cyanoalkyl-substituted polyureas in the presence of n-butylamine. The intermediate polyureas, which were not isolated, were prepared from methylenebis(4-phenyl isocyanate) with N,N′-bis(1-cyanocyclohexyl)-1,6-hexanediamine, N,N′-bis(1-cyanocyclohexyl)-m-xylylenediamine and N,N′-bis(1-cyanocyclopentyl)-1,6-hexanediamine. The polyiminoimidazolidinones were soluble in m-cresol, dimethylformamide, and chloroform and had low inherent viscosities of 0.14–0.28. Thermogravimetric analyses showed that the polyhydrouracils underwent rapid decomposition at 400°C, whereas an analogous unsubstituted polyurea decomposed at 300°C. On the other hand, the polyiminoimid-azolidinones showed no greater thermal stability than the unsubstituted polyurea.     

Synthesis of Rh(I) and Ir(I) complexes with chiral C2-multitopic ligands: Structural and catalytic properties

Four multitopic ligands, N,N′-bis[(S)-prolyl)phenylenediamine, N,N′-bis{[(S)-pyrrolidin-2-yl]methyl}phenylenediamine, N,N′-bis[(S)-N-benzylprolyl]phenylenediamine, N,N′-bis{[(S)-N-benzyl-pyrrolidin-2-yl]methyl}phenylenediamine, were synthesised and their co-ordination properties with Rh(I) and Ir(I) studied. The complexes were prepared by the reaction of [MCl(cod)]₂ with AgPF₆ and further treatment with the ligand. All ligands form one to one [ML] species with the above metal ions. The structures of these complexes were elucidated by analytical and spectroscopic data (elemental analysis, mass spectroscopy, IR, ¹H- and ¹³C-NMR). Complexes show excellent activities and enantioselectivities up to 30% for the hydrogenation of prochiral olefins under mild reaction conditions.     

Iron(II)-bis (salicyladimine) Schiff-base complexes catalyzed decomposition of hydrogen peroxide

The tetradentate Schiff-base ligands, N,N′-bis(salicylidene)-ethylenediamine (Salen), N,N′-bis(salicylidene) butylenediamine (Salbut), and N,N′-bis(salicylidene)-o–phenylenediamine, (sal-o-phen) are very strongly sorbed by cation exchange resin (Dowex-50W) with Fe²⁺ ions as a counter ion, forming stable complexes. The kinetics of the catalytic decomposition of H₂O₂ using these complexes was studied in ethanolic medium. The reaction was first-order with salen and sal-o-phen and second-order with salbut with respect to [H₂O₂]. The rate of the H₂O₂ decomposition increased either from salen to salbut or from salen to sal-o-phen. Also, the k (per g dry resin) values decreased with increasing both the particle size and the degree of resin cross-linkage. The active species formed at the beginning of the reaction, had an inhibiting effect on the reaction rate. The corresponding activation parameters were calculated from a least-squares fit of the temperature dependence of the rate constant. A reaction mechanism is proposed. © 1994 John Wiley & Sons, Inc.     

季胺基修饰的Salen配合物的合成及性质

采用季胺基取代的水杨醛(由2,4-二羟基水杨醛、1,2-二溴乙烷、高氯酸钠等为原料合成)合成了两个新型Salen配体N,N'-二{4-[[2-(三甲胺基)乙基]氧化]水杨醛}-邻苯二胺二高氯酸盐(L¹), N-(2-羟基-5-甲基二苯甲基)-N'-{4-[[2-(三甲胺基)乙基]氧化]水杨醛}-邻苯二胺高氯酸盐(L²), 并进一步合成了8个新型Salen金属配合物[ZnL¹, NiL¹, CuL¹, ZnL², NiL², CuL², MnL², CoL²]. 用¹H NMR, ¹³C NMR, FT-IR, UV-vis, MS对配体和配合物进行了表征, 测定了金属配合物的水溶性及在水中的摩尔电导率. 结果表明, 与相应母体配合物的水溶性比较, 含有季胺基修饰的Salen金属配合物的水溶性有了较大提高.     

Aggregation behaviors of amine-oxide gemini surfactants

The micellar aggregation of a series of gemini surfactants [N, N’-dimethyl-N, N’-bis(2-alkylamideethyl)-ethylenediamine oxide (alkyl?=?C₁₁H₂₃, C₁₃H₂₇, C₁₅H₃₁)] in aqueous media has been investigated. The results show that there is an excellent agreement among the critical micelle concentration (CMC) values obtained by surface tension and steady-state fluorescence methods. Because of the occurrence of self-coiling or the formation of pre-micellization, the CMC values, the I₁/I₃ values, and the micelle aggregation numbers (N_agg) at CMC (N_m) increase with the hydrophobic alkyl chain length increasing. Besides, vesicles are observed above the CMC for all these surfactants.