Tertiary Aromatic Amines Research Articles

Does the back electron transfer affect the rate of photoinducec free radical polymerization?

The specific behaviors of monomeric electron acceptor-electron donor bridged molecules and of polymeric initiator-coinitiator systems tested as free radical polymerization photoinitiating systems were observed. The obtained experimental and theoretical results suggest that the back electron transfer process probably does not control the rate of photoinitiated polymerization going with initiators tested. The phenomena observed more likely results from a different proton transfer between Rose bengal radical anion and a tertiary aromatic amine radical cation. This can be deducted on the basis of Marcus theory, describing the kinetics of photoinduced intermolecular and intramolecular electron transfer processes, and laser flash photolysis measurements.

Novel Petasis Boronic Acid—Mannich Reactions with Tertiary Aromatic Amines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Novel Petasis boronic acid–Mannich reactions with tertiary aromatic amines

Tertiary aromatic amines can serve as amine substrates for the Petasis boronic acid–Mannich reaction, providing a practical synthetic route for the CC bond formation of α-(4- N, N-dialkylamino-2-alkyloxyphenyl)carboxylic acids. The scope and limitations of this method have been examined.

Utilization of Folin-Ciocalteu phenol reagent for the detection of certain nitrogen compounds.

To determine in more detail the reaction of Folin-Ciocalteu phenol reagent with nitrogen compounds, a number of hydroxylamine-related compounds and a large number of guanidine-containing compounds were tested. In general, guanidine compounds did not react strongly unless they were hydroxyamino or hydrazino derivatives. The non-hydroxyamino paralytic shellfish poison saxitoxin, however, reacted to a significant extent. This may be due to the presence of a five-membered ring structure and its analogy to 2-aminopurines, which react strongly. A number of simpler amines were also tested. Tertiary aliphatic amines, but not primary, secondary, or quaternary amines, reacted strongly with the reagent. Primary, secondary, and tertiary aromatic amines all reacted strongly with the reagent. Reactivity was extended to pyrroles and indole derivatives but not to imidazole and benzimidazole derivatives. Defining the reactivity of Folin-Ciocalteau phenol reagent with nitrogen compounds extends the usefulness of the reagent for the detection and determination of certain nitrogen compounds in basic extracts by colorimetric means and by thin-layer chromatography.

18O incorporation in the oxidation of N-methylcarbazole by lignin peroxidase and a model compound: a mechanistic insight into the oxidative N-demethylation of aromatic tertiary amines

Using 18O labelled reactants and/or solvent, the origin of the oxygen in the products of the oxidation of N-methylcarbazole by H2O2 catalysed by lignin peroxidase and a model compound has been determined, so getting important information about the mechanism of the oxidative N-demethylation of aromatic tertiary amines.

Novel Mannich-type nucleophilic substitution reaction with tertiary aromatic amines

A novel formaldehyde-mediated condensation reaction of N,N-dialkyl aromatic amines and resonance-stabilized carbon nucleophiles is described. A condensation reaction between N,N-dimethylaniline ( 4 ) and ethyl acetoacetate ( 8 ) in the presence of formaldehyde in acetic acid took place to give 2-(4-dimethylaminobenzyl)-3-oxo butyric acid ethyl ester ( 9 ) together with the dimerization product 7 in 73 and 21% yields, respectively. This condensation reaction was further applied to the synthesis of 4-substituted dialkylaniline derivatives.

Characterization of new acrylic bone cements prepared with oleic acid derivatives

Acrylic bone-cement formulations were prepared with the use of a new tertiary aromatic amine derived from oleic acid, and also by incorporating an acrylic monomer derived from the same acid with the aim of reducing the leaching of toxic residuals and improving mechanical properties. 4-N,N dimethylaminobenzyl oleate (DMAO) was used as an activator in the benzoyl-peroxide radical cold curing of polymethyl methacrylate. Cements that contained DMAO exhibited much lower polymerization exotherm values, ranging between 55 and 62 °C, with a setting time around 16–17 min, depending on the amine/BPO molar ratio of the formulation. On curing a commercial bone cement, Palacos® R with DMAO, a decrease of 20 °C in peak temperature and an increase in setting time of 7 min were obtained, the curing parameters remaining well within limits permitted by the standards. In a second stage, partial substitution of MMA by oleyloxyethyl methacrylate (OMA) in the acrylic formulations was performed, the polymerization being initiated with the DMAO/BPO redox system. These formulations exhibited longer setting times and lower peak temperatures with respect to those based on PMMA. The glass transition temperature of the experimental cements were lower than that of PMMA cement because of the presence of long aliphatic chains of both activator and monomer in the cement matrix. Number average molecular weights of the cured cements were in the range of 1.2×105. PMMA cements cured with DMAO/BPO revealed a significant (p<0.001) increase in the strain to failure and a significant (p<0.001) decrease in Young's modulus in comparison to Palacos® R, whereas ultimate tensile strength remained unchanged. When the monomer OMA was incorporated, low concentrations of OMA provided a significant increase in tensile strength and elastic modulus without impairing the strain to failure. The results demonstrate that the experimental cements based on DMAO and OMA have excellent promise for use as orthopaedic and/or dental grouting materials. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 88–97, 2002; DOI 10.1002/jbm.10092

Singlet dioxygen formation in ozone reactions in aqueous solution

In ozone reactions, singlet dioxygen [O2(1Δg)] is formed when ozone reacts by O-atom transfer. O2(1Δg) yields were determined for more than 50 compounds using as reference the reaction of hydrogen peroxide with hypochlorite. Close to 100% yields were found in the reaction of O3 with sulfides, disulfides, methanesulfinic acid, and nitrite. In accordance with this, the only products are: methionine sulfoxide, methanesulfonic acid, and nitrate for the reaction of O3 with methionine, methanesulfinic acid, and nitrite, respectively. In the case of aliphatic tertiary amines (trimethylamine, triethylamine, and DABCO), the O2(1Δg) yields range between 70 and 90%, the aminoxide being the other major product. With EDTA and nitrilotriacetic acid (NTA), the O2(1Δg) yield is around 20%. The interpretation of the data with DABCO required the determination of the quenching constant of O2(1Δg) by this amine, kq = 1.8 × 109 dm3 mol−1 s−1 in H2O and D2O, two orders of magnitude lower than previously reported. Aromatic tertiary amines give even lower O2(1Δg) yields [N,N-dimethylaniline (7%), N,N,N′,N′-tetramethylphenylenediamine (9%)]. Substantial amounts of O2(1Δg) are also formed with the DNA model compounds, 2′-deoxyguanosine (40%) and 2′-deoxyadenosine (15%, in the presence of tert-butyl alcohol as ˙OH scavenger). The pyrimidine nucleobases only yield O2(1Δg) when deprotonated at N(1). O2(1Δg) formation is also observed with hydrogen sulfide (15%), azide (17%), bromide (56%), iodide (12%), and cyanide ions (20%). The O2(1Δg) yield from the reaction of O3 with phenols and phenolates is typically around 20%, but may rise closer to 50% in the case of pentachloro- and pentabromophenolate. Low O2(1Δg) yields are found with unsaturated acids such as dihydroxyfumarate (6%), muconate (2%), and acetylenedicarboxylate (15%). With saturated compounds, also, no O2(1Δg) (e.g. with propan-2-ol, acetaldehyde, acetaldehyde dimethylacetal and glyoxal) or very little O2(1Δg) (formic acid; 6%, at high formate concentrations) was detected. As shown with some examples, knowledge of the O2(1Δg) yield (in combination with that of other products) is a prerequisite for the elucidation of the mechanisms of O3 reactions in aqueous solutions.

Time-resolved emission studies of tris-acetylpyrene derivative of a cryptand exhibiting localised monomer, intramolecular exciplex and intramolecular excimer emissions in different environments

The tris-acetylpyrene derivative of a heteroditopic cryptand is found to be a rare supramolecular system exhibiting three emissions due to localised monomer, intramolecular exciplex and excimer emissions in different environments. The lifetime for the monomer emission is much shorter compared to that of free pyrene indicating PET from cryptand moiety to pyrene units. In presence of some transition metal ions, PET is blocked resulting in increase of the lifetime for the metal complex. The major component of the lifetime of the intramolecular exciplex is comparable with that of other polycyclic aromatic tertiary amine systems. Presence of protons in the environment facilitate intramolecular excimer formation whose lifetime is almost twice as that of the intramolecular exciplex emission of the system.

Hardness and Structure of a-CNx Films Synthesized by Chemical Vapor Deposition

Mechanically hard a-CNx films were synthesized using a combination of ion bombardment and the chemical vapor deposition process using the dissociative excitation reaction of BrCN with Ar metastable atoms. Nanoindentation tests disclosed that the indentation hardness, Young's modulus and elastic recovery increased with increasing ion-accelerating voltage. Moreover, the degree of flow among clusters decreased in the ion-bombarded sample. The D (disordered)-band absorption on an infrared absorption spectrum was replaced by a C–N absorption assigned to the tertiary aromatic amine. These results suggest that the internal and external structures of the carbon nitride cluster change from the two-dimensional order to the three-dimensional order of C–N. The structure of hard a-CNx is clearly distinguishable from nitrogen-containing diamond-like carbon.

New Dendritic Materials as Potential OLED Transport and Emitter Moeities

Traditionally, organic light-emitting devices (OLEDs) are prepared with discrete layers for hole and electron transport. Different materials must be used for these layers because most materials will preferentially transport one charge carrier more efficiently than the other. In most cases, the emitter material serves a dual purpose as both the emitter and the hole or electron transporter. One of the major failure modes of OLEDs results from thermal instabilities of the insulating organic layers caused by joule heating during device operation. The problem is most pronounced for the hole transporting layer (HTL) material which are usually tertiary aromatic amines (i.e., TPD and NPD). This has been attributed to the relatively lower glass transition temperatures (Tg) and resulting inferior thermal stabilities compared to the other materials making up the device. Many researchers have produced HTL materials with higher Tgs based on tertiary aromatic amine oligomers and starburst compounds. Starburst or model dendritic materials offer the advantages of high thermal stabilities and multi-functionality.

Physico-chemical characterisation of atmospheric aerosols in a rural area affected by the aznalcollar toxic spill, south-west Spain during the soil reclamation activities

High levels of atmospheric contamination due to the re-suspension of pyrite particles from the mining waste slurry were recorded in the Guadiamar valley (the Guadiamar is a tributary of the Guadalquivir river) after the toxic spill of Aznalcóllar, north of the Doñana Natural Park (SW Spain). Major high-particulate events occurred during the extraction of the pyrite-rich mud layer, which covered an extensive area of the valley downstream of the confluence of the Agrio and Guadiamar rivers. This study deals with the monitoring of the ambient air quality at two stations near the village of Aznalcázar in the central part of the flooded area. Although the Spanish legal limit for atmospheric particles and lead in environmental air were not exceeded, high daily levels of total suspended particles (TSP) and of some elements with an environmental significance (As, Cd, Cu, Mn, Ni, Pb, Sn, Tl and Zn) were recorded at Aznalcázar and in the Guadiamar valley during soil reclamation (July–August 1998). Despite a progressive decrease in TSP levels through September–October 1998, background was higher than the levels for the May–June period. Evolution of levels for most of the elements studied showed a similar trend. The exceptions were copper, which was partially increased by other emission sources such as fumigation activities, and sodium, which remained at relatively constant levels during the study period because of its marine origin. The physico-chemical characterisation of the atmospheric particulates allowed us to determine the major grain size modes of the pyrite related elements and the solubility of the potentially toxic elements, and to identify the major particulate types present in the atmosphere in the area. Secondary and tertiary aromatic amines (i.e. alkyldiphenylamines and phenylcarbazoles, respectively) were identified in the suspended particles and in the vapour phase collected at the same station as the TSP samples. As some of these aromatic amines had been previously identified in the pyrite sludge, it is assumed that fine sludge particles containing aromatic amines were re-suspended in the atmosphere. The highest concentrations of aromatic amines in the particulate phase were recorded in August 1998 during the pyrite slurry extraction in the proximity of the Aznalcazár sampling site. Despite a sharp drop in the suspended particles of the aromatic amine concentrations, a significant concentration was detected in the vapour phase (<1.2 mm) during autumn, probably because of longer residence time in the atmosphere. Although health hazards associated with the presence of these aromatic amines are unknown, their acute toxicity exceeded that of urban aerosols.

Design of eutectic photoinitiator blends for UV/visible curable acrylated printing inks and coatings

The optimisation of photoinitiator systems used in UV printing inks and coatings has been carried out by means of Design of Experiments (Mixture designs). Mixture designs have been used to improve the reactivity of photoinitiator blends in order to design cost effective, synergistic, near eutectic photoinitiator blends for curing UV printing inks. Both the reactivity and bulk stability of photoinitiator blends have been studied. The photoinitiator blends consisted of three commercial photoinitiators, benzophenone (BP), isopropyl thioxanthone (ITX), which are Type II photoinitiators and benzil dimethyl ketal (BDK) a Type I photoinitiator. Ethyldimethylamino benzoate (EPD), a commercial aromatic tertiary amine, which is an efficient electron/proton donor was used to enhance the reactivity of the Type II photoinitiators. The results highlighted that the EPD content plays a crucial role in the final reactivity of the photoinitiator blends. Relatively high proportions of EPD with respect to the overall centroid (25% each component) were required to design photoinitiator blends of enhanced reactivity. These results agreed with mechanistic studies published in the literature where it was observed that with Type II photoinitiators, such as BP and ITX, the tertiary amine synergist acted as the main initiating radicals of the polymerisation process. On the other hand, from the stability point of view, high proportions of EPD decreased the stability (eutectic properties) of the photoinitiator blends. BP showed good solvating properties in the photoinitiator blends and had the highest influence on stability of the photoinitiators studied. Relatively high proportions of BP enhanced the stability of photoinitiator blends. Multiple response optimisation for stability and reactivity resulted in photoinitiator blends that exhibited both enhanced reactivity and stability.

EVALUATION OF TERTIARY AMINE CO-INTIATORS USING DIFFERENTIAL SCANNING PHOTOCALORIMETRY

The purpose of this investigation was to compare the degree of photo- and thermal-polymerization obtained using various tertiary amine co-initiators of differing reactivities and molar concentrations, utilizing differential scanning photocalorimetry (DPC) and DSC. Amines tested were 2-(dimethylamino)ethyl methacrylate (A), triethanolamine (B), N,N,3,5-tetramethyl-aniline (C), ethyl 4-dimethylaminobenzoate (D), 0.95 (A) and 0.05 (D) in combined mixture (E), 4-N,N-(dimethylamino)phe-nylacetic acid (F) and a newly-synthesized tertiary aromatic amine methacryloxyethyl substituted 4-N,N-(dimethyla-mino)phenylacetamide (G). The monomer system consisted of Bis-GMA and triethylene glycol dimethacrylate neat resins, and 0.5% camphoroquinone for all groups tested. Samples of the blended monomers with 0.5–4.0 mol/eq (co-initiator to initiator) were irradiated with visible light under N2. The heat of reaction (ΔH) was calculated for each run in order to determine the degree of polymerization (DP). D resulted in a significantly higher degree of photopolymerization than A or B (p<0.05). No significant differences were noted between C, E, F and G (α= 0.05). ΔH values for DSC correlated well with those of DPC. DPC appears to be an efficient tool in the evaluation of photo-initiated free radical polymerized systems.

Oxidation of N-methyl-9-t-butylacridane by iodosylbenzene catalyzed by tetrakis(pentafluorophenyl) porphyrin iron(III). A tool to investigate the mechanism of the oxidative N-demethylation of aromatic tertiary amines

Abstract The ce:simple-parahIO promoted oxidation of N -methyl-9- t -butylacridase ( 1 ) catalyzed by tetrakis(pentafluorophenyl) porphyrin iron(III) leads first to 9- t -butylacridane and then to acridine. It is suggested that 1 can represent a reliable machanistic probe to detect the intervention of radical cations in the oxidation of aromatic amines.

Free radical polymerization initiated via photoinduced intermolecular electron transfer process: kinetic study 3

Various electron donors and electron acceptors have been tested in order to examine the possibility of the application of the Marcus equation to the description of the kinetics of free radical polymerization photoinitiated via photoinduced electron transfer (PET). Variations of the driving force of the electron transfer, for selected dyes (xanthene dyes, camphorquinone), were introduced by using: a series of tertiary aromatic amines (TAAs) and N-phenylglycine derivatives; a series of electron acceptors and only one type of electron donor (cyanine cations with tetraorganylborate anion); a mixed system with a series of benzophenones as electron acceptors and TAAs as electron donors. Several important conclusions follow from the experimental data. (1) For the case with the rate of PET much lower than the rate of diffusion controlled processes, the Marcus theory can be used for analysing or predicting the ability of organic redox systems for light-induced free radical polymerization. (2) For a process controlled by diffusion, the reactivity of free radicals formed as a result of PET limits the rate of initiation of polymerization. It is shown that this relationship can be also presented as a function of thermodynamic driving forces of the photoredox reaction ( − G°). For this type of process, the relationship between the rate of polymerization and − ΔG° is linear, indicating the ‘inverted-region-like’ kinetic behaviour. Additionally, it is shown that the bleaching process of the dyes competes with the polymerization photoinitiation in a way that suggests that, after free radical formation, two parallel reactions occur and that the rate of bleaching can be expressed as a fraction of the total rate of electron transfer.

Oligomerization of Aromatic Tertiary Amines

Abstract The oligomerization of some tertiary aromatic amines was studied using ferric chloride in a variety of solvent. The predominant dimer formation of triphenylamine (TPA) was observed in chloroform at 0 °C where concentration of TPA was 0.125 mmol/l and the molar ratio of ferric chloride to TPA was 4. Except for N-methyldiphenylamine, high molecular weight oligomers were formed in a variety of solvents.

Chemical modification of hydroxyl functions: Introduction of hydrolyzable ester function and bactericidal quaternary ammonium groups

Polymers carrying a hydrolyzable ester function and bactericidal quaternary ammonium salts were successfully synthesized in 2 steps. The first one was the modification of hydroxyl functions of poly(vinyl alcohol) by chloroacetic anhydride. The structure of synthesized polymers was confirmed by infrared (IR), 1H-, and 13C- nuclear magnetic resonance (NMR). The kinetic results were consistent with a 1-order reaction, and the activation energy in the case of total modification was found to be 16.8 kJ mol−1. The second step was the quaternization of the pendant chlorine atom with a long alkyl chain or aromatic tertiary amines. The percentage of grafting was almost total, except with 3-diethylaminophenol, probably due to steric hindrance. The thermal degradation of polymers was studied. Side chains carrying quaternary ammonium salts begin to degrade at 168°C with the emission of chloride and amine compounds. At about 250°C, acetic and chloroacetic acid are evolved due to acetate and chloroacetate side chains. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2657–2666, 1998

Synthesis of a diphenylethylene derivative carrying aromatic tertiary amine groups and its use in chain end functionalization of alkyllithium-initiated polymerizations

Synthesis of a diphenylethylene derivative carrying aromatic tertiary amine groups and its use in chain end functionalization of alkyllithium-initiated polymerizations

Synthesis of a diphenylethylene derivative carrying aromatic tertiary amine groups and its use in chain end functionalization of alkyllithium-initiated polymerizations

1,1-Bis(4-dimethylamino)phenyl)ethylene was successfully synthesized through the 'Wittig-type' reaction of 4,4'-bis(dimethylamino)benzophenone with the 'Tebbe' reagent. The methylenation yields were over 80 wt.-% on the basis of the initial amount of benzophenone derivative used. Terminally functionalized polymers having aromatic tertiary amine groups at one end or at both ends were prepared by the crossover reactions of n-butyllithium (n-BuLi), poly(styryl)lithium (PSLi), and poly(isoprenyl)lithium (PILi) with the diphenylethylene analogue. The functionalization yields were over 87 mol.-% based on the results of 'H NMR spectroscopic analysis. The number-average molecular weights of the polymers based on the ratio [gram of monomer]/[mole of initiator] are in good accordance with those observed from size exclusion chromatographic and 'H NMR spectroscopic analysis (3,0 x 10 3 ∼7,5 x 10 3 g/mol).