Series Of Tertiary Amines Research Articles

A Facile Oxidation of Tertiary Amines to Lactams by Using Sodium Chlorite: Process Improvement by Precise pH Adjustment with CO2

AbstractBy using cheap and innocuous sodium chlorite, a series of tertiary amines have been oxidized to the corresponding lactams with good selectivity and high yield. In this method, neither transition-metal catalyst nor oxidant was used. In the oxidation step, the pH of the sodium chlorite was precisely adjusted to pH around 6 using CO2, such pH is a compromise between oxidative properties, chemical stability, and unwanted precipitation. In addition, buffer salts are not necessary, which allows this oxidation reaction to be performed under safe and environmentally benign conditions.

Quaternized poly (2,6‐dimethyl‐1,4‐phenylene oxide) crosslinked by tertiary amine and siloxane for anion exchange membranes

AbstractA series of tertiary amine and siloxane crosslinked composite anion exchange membranes were prepared by incorporating 2‐(3,4‐epoxycyclohexyl) ethyltrimethoxysilane (EHTMS) and N,N,N′,N′‐Tetramethyl‐1,6‐hexanediamine (TMHDA) into N‐Methyldiethanolamine (MDEA)‐functionalized poly (2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) backbone via sol‐gel process. The resultant membranes named as AEM‐X (X = 1, 2, 3, 4), which own a three‐dimensional (3D) cross‐linking structure, exhibit superior swelling resistance, mechanical properties, even the thermal stability is up to 220°C. Compared with AEM‐1 (contains no crosslinker), the swelling ratio of AEM‐2 obviously decreases by 10.2% at 80°C, while the OH− conductivity of AEM‐2 has a merely 1.9% decline (20.6 mS cm−1) at 80°C and can maintain 67% of its initial value in a 2 M aqueous NaOH at 80°C for 240 h. The simultaneous introduction of inorganic siloxane and organic linear crosslinker provides a new idea for the preparation of anion exchange membranes with largely improvement in dimensional stability and alkali resistance while the ionic conductivity is kept at comparatively high level.

Synthesis, characterization and excellent antibacterial property of cellulose acetate reverse osmosis membrane via a two-step reaction

In order to improve the antibacterial efficiency and spectrum of cellulose acetate reverse osmosis membrane (CA–RO), both quaternary ammonium and bromoacetyl groups were introduced into cellulose diacetate under mild conditions forming CA–RO with bi-antibacterial groups for seawater desalination. Bromoacetyl bromide and a series of tertiary amine were chosen as the modification agents respectively. The characterization results showed that both two antibacterial groups were successfully introduced with a certain density. The obtaining membrane had a less hydrophilic but more electronegative surface as well as improved mechanical property. The flux values increased firstly and decreased subsequently after twice modifications while the salt rejection rose. The membrane modified with N,N-dimethyloctylamine (DMOA) had the optimal comprehensive performance of flux and salt rejection. The antibacterial testing results indicated that the resulting RO membranes showed high antibacterial efficiency and broad-spectrum. Their bactericidal rates against gram-negative Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus) were more than 99.9%.

Synthesis, self-assembly, and pH-responsive drug release of PHMEMA-PEG-PHMEMA ABA triblock copolymers

A series of tertiary amine containing PHMEMA-PEG-PHMEMA ABA triblock copolymers were synthesized by atom transfer radical polymerization (ATRP) using bromine-capped poly(ethylene glycol) (Br-PEG-Br) and 2-(hexamethyleneimino)ethyl methacrylate (HMEMA) as macro-initiator and monomers, respectively. The chemical structures and molecular weights of triblock copolymers were characterized by 1H NMR and gel permeation chromatography (GPC). The self-assembly behaviors of copolymers in different pH conditions were studied by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Triblock copolymers self-assembled into micelles in water (pH 7.4) and the micelles disassembled at acidic pH (pH 5.0). Anticancer drug doxorubicin (DOX) was used as a drug model and physically encapsulated into polymeric micelles. The drug release of DOX-loaded polymeric micelles was pH-responsive; the drug-loaded micelles that had higher contents of tertiary amine in polymer pendant groups showed faster release speed. In addition, the drug-loaded micelles showed excellent inhibition efficacy against HeLa cells in vitro.

Ligand‐Assisted Pd‐Catalyzed N‐Dealkylative Carbonylation of Tertiary Amines with (Hetero)Aryl Halides to Tertiary Amides

AbstractThis work reports an efficient synthesis of tertiary amides using a ligand‐assisted Pd‐catalyzed carbonylation of (hetero)aryl halides with tertiary amines. A key step in this reaction is C(sp3)−N bond cleavage using CuO as an oxidant. The reaction proceeds with high efficiency employing a bidentate phosphine ligand (dppp), which is a key for the carbonylation of unreactive (hetero)aryl halides and series of tertiary amines at atmospheric pressure of carbon monoxide.

Transition-Metal-Free C–N Bond Activation: Synthesis of α,α-Bis(arylthio) Aldehydes

A novel and convenient tandem reaction of I₂-catalzyed C–N bond activation of tertiary amines and subsequent aryl thiolation has been explored. A variety of disulfides and series of tertiary amines were efficiently converted into the corresponding α,α-bis(arylthio) aldehydes in moderate to good yields. The reaction proceeded well under transition-metal-free conditions via a C–N activation process.

ChemInform Abstract: Hydroamination of Terminal Alkynes with Secondary Amines Catalyzed by Copper: Regioselective Access to Amines.

AbstractA series of tertiary amines (III) and (V) is readily prepared by a copper‐catalyzed solvent‐free hydroamination of alkynes (I) with secondary amines (II) and (IV) followed by reduction of intermediate (E)‐enamines.

High Antimicrobial Effectiveness with Low Hemolytic and Cytotoxic Activity for PEG/Quaternary Copolyoxetanes

The alkyl chain length of quaternary ammonium/PEG copolyoxetanes has been varied to discern effects on solution antimicrobial efficacy, hemolytic activity and cytotoxicity. Monomers 3-((4-bromobutoxy)methyl)-3-methyloxetane (BBOx) and 3-((2-(2-methoxyethoxy)ethoxy)methyl)-3-methyloxetane (ME2Ox) were used to prepare precursor P[(BBOx)(ME2Ox)-50:50–4 kDa] copolyoxetane via cationic ring opening polymerization. The 1:1 copolymer composition and Mn (4 kDa) were confirmed by 1H NMR spectroscopy. After C–Br substitution by a series of tertiary amines, ionic liquid Cx-50 copolyoxetanes were obtained, where 50 is the mole percent of quaternary repeat units and “x” is quaternary alkyl chain length (2, 6, 8, 10, 12, 14, or 16 carbons). Modulated differential scanning calorimetry (MDSC) studies showed Tgs between −40 and −60 °C and melting endotherms for C14–50 and C16–50. Minimum inhibitory concentrations (MIC) were determined for Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. A systematic dependence of MIC on alkyl chain length was found. The most effective antimicrobials were in the C6–50 to C12–50 range. C8–50 had better overall performance with MICs of 4 μg/mL, E. coli; 2 μg/mL, S. aureus; and 24 μg/mL, P. aeruginosa. At 5 × MIC, C8–50 effected >99% kill in 1 h against S. aureus, E. coli, and P. aeruginosa challenges of 108 cfu/mL; log reductions (1 h) were 7, 3, and 5, respectively. To provide additional insight into polycation interactions with bacterial membranes, a geometric model based on the dimensions of E. coli is described that provides an estimate of the maximum number of polycations that can chemisorb. Chain dimensions were estimated for polycation C8–50 with a molecular weight of 5 kDa. Considering the approximations for polycation chemisorption (PCC), it is surprising that a calculation based on geometric considerations gives a C8–50 concentration within a factor of 2 of the MIC, 4.0 (±1.2) μg/mL for E. coli. Cx-50 copolyoxetane cytotoxicity was low for human red blood cells, human dermal fibroblasts (HDF), and human foreskin fibroblasts (HFF). Selectivities for bacterial kill over cell lysis were among the highest ever reported for polycations indicating good prospects for biocompatibility.

Structure–function study of tertiary amines as switchable polarity solvents

A series of tertiary amines have been screened for their function as switchable polarity solvents (SPS). The relative ratios of tertiary amine and carbonate species as well as maximum possible concentration were determined. A new form of SPS with an amine : carbonate ratio significantly greater than unity has been identified. The N,N-dimethyl-n-alkylamine structure has been identified as important to the function of an SPS.

Discovery of Tertiary Amine and Indole Derivatives as Potent RORγt Inverse Agonists.

A novel series of tertiary amines as retinoid-related orphan receptor gamma-t (RORγt) inverse agonists was discovered through agonist/inverse agonist conversion. The level of RORγt inhibition can be enhanced by modulating the conformational disruption of H12 in RORγt LBD. Linker exploration and rational design led to the discovery of more potent indole-based RORγt inverse agonists.

Hydrogen Atom Abstraction Reactions from Tertiary Amines by Benzyloxyl and Cumyloxyl Radicals: Influence of Structure on the Rate-Determining Formation of a Hydrogen-Bonded Prereaction Complex

A time-resolved kinetic study on the hydrogen atom abstraction reactions from a series of tertiary amines by the cumyloxyl (CumO(•)) and benzyloxyl (BnO(•)) radicals was carried out. With the sterically hindered triisobutylamine, comparable hydrogen atom abstraction rate constants (k(H)) were measured for the two radicals (k(H)(BnO(•))/k(H)(CumO(•)) = 2.8), and the reactions were described as direct hydrogen atom abstractions. With the other amines, increases in k(H)(BnO(•))/k(H)(CumO(•)) ratios of 13 to 2027 times were observed. k(H) approaches the diffusion limit in the reactions between BnO(•) and unhindered cyclic and bicyiclic amines, whereas a decrease in reactivity is observed with acyclic amines and with the hindered cyclic amine 1,2,2,6,6-pentamethylpiperidine. These results provide additional support to our hypothesis that the reaction proceeds through the rate-determining formation of a C-H/N hydrogen-bonded prereaction complex between the benzyloxyl α-C-H and the nitrogen lone pair wherein hydrogen atom abstraction occurs, and demonstrate the important role of amine structure on the overall reaction mechanism. Additional mechanistic information in support of this picture is obtained from the study of the reactions of the amines with a deuterated benzyloxyl radical (PhCD(2)O(•), BnO(•)-d(2)) and the 3,5-di-tert-butylbenzyloxyl radical.

Flotation of kaolinite with dodecyl tertiary amines

The flotation of kaolinite using a series of tertiary amines (N,N-dimethyl-dodecyl amine (DRN), N,N-diethyl-dodecyl amine (DEN), N,N-dipropyl-dodecyl amine (DPN) and N,N-dibenzyl-bodecyl amine (DBN)) was investigated. The results show that the maximum recoveries of kaolinite for DEN, DPN and DRN are 93%, 88% and 84%, respectively, but that of DBN is very low. On the basis of zeta potential and FT-IR spectra, the ionization of surface hydroxyl and isomorphic exchange of surface ions account for the charging mechanisms of kaolinite surface. The adsorption mechanism of tertiary amines on kaolinite surface is mainly electrostatic. The isoelectric point (IEP) of kaolinite increases from 3.4 to some more positive points after the interaction of kaolinite with the four tertiary amines. The FT-IR spectra of kaolinite change with the presence of some new sharp shapes belonging to the tertiary amines. The inductive electronic effects and space-steric effects of -CH3, -C2H5, -C3H7 and -C7H7 bonding to N atom result in different collecting power of the four tertiary amines.

Substituent effects in kaolinite flotation using dodecyl tertiary amines

The flotation behavior of kaolinite was investigated using a series of tertiary amines (DRN, DEN, DPN and DBN). Maximum recoveries of kaolinite were 93%, 88% and 84% for DEN, DPN and DRN, respectively. The recovery for DBN was very low. On the basis of the Zeta potential and FT-IR spectra, the ionization of surface hydroxyl and the isomorphic exchange of surface ions accounts for the charging mechanisms of the kaolinite surface. The adsorption mechanism of tertiary amines onto the kaolinite surface was mainly electrostatic. We determined that the IEP of kaolinite increased from 3.4 to higher values after the interaction of kaolinite with the four tertiary amines. FT-IR spectra of kaolinite changed to include sharp peaks of tertiary amines. Inductive electronic effects and space-steric effects of –CH 3, –C 2H 5, –C 3H 7 and –C 7H 7 bound to the N atom result in different collecting powers for the four tertiary amines.

Zinc–salophen complexes as selective receptors for tertiary amines

Zinc–salophen compounds 1–3 incorporating in the given order 1,2-diaminobenzene, 2,3-diaminonaphthalene, and 9,10-diaminophenantrene moieties were synthesised. Their binding properties toward a series of tertiary amines were assessed by UV-Vis and fluorescence spectroscopy in chloroform solution. Unprecedented selectivities of quinuclidine vs. triethylamine higher than 105 were recorded, thereby revealing the dramatic influence of steric effects on axial coordination of tertiary amines. X-Ray diffraction analyses showed that in the solid state compound 2 is dimeric, but its 1 : 1 quinuclidine complex is monomeric. Strong indications were obtained that both free receptors and their amine adducts are monomeric in dilute chloroform solution.

Reactivity and molecular recognition: amine methylation by an introverted ester.

We report a host molecule with an inwardly directed methyl ester and its reaction with a series of tertiary amines. The reaction product is a complex of the host carboxylate with a guest quaternary ammonium salt. The rate of the reaction is highly dependent on the suitability of the amine to occupy the host cavity and the intrinsic reactivity of the resulting complex. A kinetic study of the reaction of 2-(dimethylamino)ethanol to produce choline gives the activation parameters DeltaH = 25.1 +/- 0.5 kcal mol-1 and DeltaS = 12 +/- 2 cal mol-1 K-1. The complex, once formed, is poised to reach the transition state; a rate acceleration of greater than 2 x 104 fold is estimated when compared with similar reactions having no supramolecular effects.

A Theoretical Evaluation of the pKa for Twisted Amides Using Density Functional Theory and Dielectric Continuum Methods

We present an ab initio study of the pKa of a series of twisted amides in aqueous solution. The shift of the pKa with respect to the known value for trimethylamine (TMA) is used in the evaluation. Calculations were made with density functional theory using the B3PW91 functional. Aqueous solvent effect is introduced by use of the polarizable continuum model. The protocol is tested on a series of tertiary amines and twisted amides, and a good agreement with the available experimental data is found. Finally, mechanistic implications of the change in basicity of the nitrogen as a function of the twist of the amide bond for the activation of C−N bond hydrolysis are discussed.

Noncomplexing Tertiary Amines as “Better” Buffers Covering the Range of pH 3−11. Temperature Dependence of Their Acid Dissociation Constants

Most of a broad series of buffers developed by Good (often called "Good's" or "Good" buffers) have been shown to cause metal ion interference as a result of complexation. A series of tertiary amines, devoid of hydroxy groups or other weak donors on the α, β, or γ carbons, have been developed as "Better" pH buffers which, as a result of steric hindrance, are incapable of forming even weak complexes with metal ions. As a result, they avert interferences of the type often encountered in metal ion studies which require buffer use. The compounds studied are alkyl and alkylsulfonate derivatives of morpholine (3), piperazine (3), ethylenediamine (3), and methylenediamine (1). With the exception of the morpholine derivatives, these compounds have two protonatable sites and, therefore, can be used to buffer two separate pH regions. A series of 10 buffer compounds span the entire range of pH 3-11. The acid dissociation constants for these compounds have now been determined in aqueous solution at 15, 25, 35 and 45 °C, μ = 0.10 M. From these data, apparent enthalpy and entropy values have been calculated to permit application at other temperatures as well. These buffers are recommended for use in all situations in which metal ions are present. All of the reported compounds are now commercially available.

Preparation of Polymer-Bound 1H-Benzotriazole, a New Potential Scaffold for the Compilation of Organic Molecule Libraries

An efficient method for the preparation of polymer-bound 1H-benzotriazole has been devised. The reaction of Merrifield resin with sodium 3-nitro-4-aminophenolate and the subsequent reduction and reaction with isoamyl nitrite afforded benzotriazole preloaded resin. A series of tertiary amines and a tosylamide were prepared using solid-phase benzotriazole-mediated transformations.

Relationship between the octanol-water partition coefficient of tertiary amines and their effect of ?selective? uncoupling of photophosphorylation

A series of tertiary amines was investigated for effects on the transmembrane proton potential difference (Δ [Formula: see text]H), on photophosphorylation and on electron-flux control related to the intrathylakoid proton potential ([Formula: see text]HI), using isolated chloroplasts ofSpinacia oleracea L. As indicated by 9-aminoacridine fluorescence and [14C]methylamine uptake, all amines studied inhibited a build-up ofΔ [Formula: see text]H and, in parallel, ATP synthesis. Even whenΔ [Formula: see text]H was low, strong[Formula: see text]H1-dependent electron-flux control was observed under the influence of tertiary amines. The strength of flux control in the presence of lowΔ [Formula: see text]H and the effectiveness of inhibition of ATP synthesis linearly increased with the lipophilicity of the amines. The most effective of the amines tested caused 50% inhibition of ATP synthesis at a concentration of 6 μM, which is about 1000-fold lower than the concentration required for inhibition by methylamine. The data presented indicate the existence of two proton domains in the thylakoid vesicles, one of them feeding the ATP-synthase, the other the sites of pH-dependent electron-flux control. It is concluded that tertiary amines develop their action in a lipophilic domain of the thylakoid membrane, in the vicinity of the ATP-synthase complex. A mechanism for 'selective' uncoupling and for the maintenance of[Formula: see text]HI-dependent electron flux control in the presence of lowΔ [Formula: see text]H is discussed.

Quenching of singlet and triplet states of p-N,N-dimethylaminobenzonitrile by tertiary amines. Intramolecular charge-transfer state and excited-state three-electron bond

The photolysis of p-N,N-dimethylaminobenzonitrile (DMABN) in a series of tertiary amines has been studied in detail. Interaction rates between the tertiary amines and three excited electronic states of DMABN, the intramolecular charge-transfer state, the twisted exciplex state and the triplet state, have been measured directly. These rates are strongly influenced by the electronic and geometric structures of the DMABN excited states. Triplet-state reaction is controlled by the energetics and is attributed to hydrogen-atom abstraction. Singlet-state reactions are controlled by the steric effects; the twisted state is more reactive than the relatively planar one. We attribute the singlet-state reaction to three-electron interaction with amine lone-pair electrons. These results demonstrate that the twisted single state (TICT state) can be satisfactorily viewed as a charge-localized biradical state, while the lowest triplet state cannot. These conclusions are further confirmed by experiments using planar analogue molecules which show no strong three-electron interaction. This study provides a novel example of how a single bond rotation can change the reactivity of a molecule by orders of magnitude.