Synthesis of 1,3,5,5-tetranitrohexahydropyrimidine

1,3,5,5-Tetranitrohexahydropyrimidine, (1), was synthesized by the oxidative nitrolysis of 1,3-diisopropyl-5,5-dinitrohexahydropyrimidine, (2), with 90% nitric acid. The course of the reaction was influenced by both the n-alkyl substituents and the nitrolyzing medium. Compound 1 was synthesized by nitrolysis of N,N-diisopropyl or dicyclohexyl substituents, while dimethyl, diethyl, or other di-n-alkyl substituents yielded ring-cleaved products 3 and/or 4. Similar effects were observed by varying the nitric acid concentration. The formation of nitramine products, rather than nitrosamine or alkyl amide products that generally result from tertiary amine nitrolysis, is attributed to conformational changes in a postulated nitronium ion-amine complex intermediate.     

Effect of tertiary amines on yellowing of UV‐curable epoxide resins

The work reported demonstrates that the yellowness of UV‐curable epoxide resins can be improved by adding certain tertiary amines in appropriately determined amounts. According to the results of our experiments, 2.0 wt% benzoyl peroxide added to a resin effectively enhances the crosslinking density, and phenolic free radicals are produced during UV curing, which consequently induce yellowness via the reaction of oxygen and the free radicals. Imidazole (1‐amine) and tertiary amines, including 1,2‐dimethylimidazole (2‐amine), 2,4,6‐tris(dimethylaminomethyl)phenol (3‐amine), 1‐methylimidazole (4‐amine) and 2‐methylimidazole (5‐amine), were chosen to be added to resins, and their effects on UV conversion and yellowness were investigated. According to the experimental results, tertiary amines in the resin can provide a certain degree of improvement in yellowness index (ΔYI) and color parameter (ΔE*_ab) of the resin sample. Whatever the type of tertiary amine, it is found that the optimum content of amine in resin is 1.0 wt%. Also, among the studied amines, the 3‐amine exhibits the highest UV reactivity and the best efficiency for yellowness improvement with values of Δa*, Δb*, ΔYI and ΔE*_ab as low as ? 1.4, 6.23, 11.27 and 6.48, respectively. Copyright © 2007 Society of Chemical Industry     

Study on the Nitrolysis of Hexamethylenetetramine by NMR spectrometry

The nitrolysis of hexamethylenetetramine (hexamine, HA) and 1,3,5-trioxane was studied by NMR spectrometry. It was found that the structure of the nitrolysis products of the trioxane could be monomethylenedinitrate, dioxymethylenenitronitrate and trioxymethylenenitronitrate, O₂N(OCH₂)_nONO₂(n = 1,2,3). Comparison of the ¹H and ¹³C spectra of the nitrolysis mixture of HA with the nitrolysis products of trioxane proved that in the nitrolysis mixture of HA the methylene group which cannot be used to form 1,3,5-triazacyclohexane (hexogen, RDX)appears in compound (2) and not in compound (1).     

Selective amidation of fatty methyl esters with N-(2-aminoethyl)-ethanolamine under base catalysis

The reaction of N-(2-aminoethyl)-ethanolamine (AEEA) with saturated fatty methyl esters derived from coconut oil occurs under noncatalyzed conditions to yield principally N-(2-hydroxyethylamino)-ethyl fatty amide,1, derived from the condensation of the primary amine moiety of AEEA with the methyl ester. In the presence of 0.25 wt % sodium methoxide at low reaction temperatures (<90 C), 2 carboxamides are formed, the secondary monoamide,1 and also the tertiary monoamide, N-(2-aminoethyl)-N-(2-hydroxyethyl) fatty amide,2. As this mixture of secondary and tertiary monoamides is heated to higher reaction temperatures (>120 C), the concentration of secondary monoamide1 increases with a concomitant decrease in tertiary monoamide2. As the reaction time is increased at the elevated temperature, the tertiary monoamide continues to disappear. Increasing the base concentration to 2.5 wt % sodium methoxide, promotes selective formation of amide2 at low temperature. The results constitute evidence that at least 2 mechanisms are operating in fatty methyl ester amidations with AEEA and provide a classic example of thermodynamic vs kinetic control. Because amides1 and2 are intermediates to imidazoline amphoteric surfactants (powerful detergents, wetting agents, emulsifiers and so forth), knowledge of the reaction mechanisms in operation during the condensation of fatty methyl esters with AEEA will permit better understanding of the resultant products and the related processing conditions.     

A Groundbreaking Stepwise Protocol to Prepare HMX from DPT: New Mechanism Hypothesis and Corresponding Process Study

1,3,5,7‐Tetranitro‐1,3,5,7‐tetraazacyclooctane(HMX) is one of the most powerful and widely used explosives. 3,7‐Dinitro‐1,3,5,7‐tetraazabicyclo[3.3.1] (DPT) is an important precursor in the production of HMX. A new reaction mechanism including nitrolysis, nitrosolysis and nitrolysis processes in fuming HNO₃ was put forward. The stable key intermediate 1‐nitroso‐3,5,7‐trinitro‐1,3,5,7‐tetraazacyclooctane (MNX) was isolated and characterized. Based on the new mechanism, a stepwise method to prepare HMX from DPT was developed. The influence factors on the yields of MNX such as reaction temperature, loading amounts of HNO₃, NaNO₂ and NH₄NO₃ were investigated. Under the optimized conditions, MNX was obtained with a satisfactory yield of 84.0 %. MNX could be efficiently and smoothly nitrolyzed in fuming nitric acid and afforded pure β‐HMX with excellent yield up to 92.8 %. The overall yield of the stepwise procedure was as high as 78.0 %, much higher than traditional one‐pot nitrolysis protocols.     

Tetrathiafulvalene. XXVIII. Diastereoselektive Bildung unsymmetrisch substituierter Tetrathiafulvalene

Tetrathiafulvalenes. XXVIII. Diastereoselective Formation of Unsymmetrically Substituted Tetrathiafulvalenes As a part of our work on chemistry of tetrathiafulvalenes, we make a contribution to elucidate the mechanism of forming tetrathiafulvalenes starting from 1,3-dithiole derivatives. We describe the synthesis of unsymmetrically substituted tetrathiafulvalenes ( 8a–i ) starting with the 2H-1,3-dithiolium salt ( 7a–i )/tert. amine, 2-ethylthio-1,3-dithiolium salt ( 5a–i )/triphenylphosphine or 1,3-dithiole-2-thione ( 4a–i )/triethyl phosphite. If the 1,3-dithiole derivatives are substituted by bulky groups the isolation of the cis- and trans-isomers was possible due to differences in the solubility. In these cases ( 8c–i ) the predominant formation of the cis-isomer is observed in the reaction of 2-ethylthio-1,3-dithiolium salts ( 5c–i ) with triphenylphosphine or 1,3-dithiole-2-thiones ( 4c–i ) with triethyl phosphite. This result is in agreement with the formation of an intermediate, analogously to the Wittig reaction. In the reaction of 2H-1,3-dithiolium salts ( 7a–i ) with tertiary amines the relation of isolated cis- and trans-isomers is not 1:1 and depends on the bulkiness of the tertiary amine. These observations exclude in these three reactions a carbene mechanism for the dimerization of the 1,3-dithiole units to tetrathiafulvalenes.     

Homogeneous Catalytic Cleavage of Saturated Carbon-Nitrogen Bonds

An evaluation of the catalytic reactivity of [CPD (CO)₂RuH]₂ (1) and (CPD)(CO)₃Ru (2) (where CPD = tetraphenylcyclopentadienone) with amines suggests that these complexes catalyze C-N bond cleavage by activating C-H bonds alpha to the nitrogen atom of tertiary, secondary and primary amines at ca. 140° C. When two different amines are used, transalkylation takes place. With secondary and primary amines, ammonia and tertiary amines are formed. A series of amine complexes (CPD)(CO)₂Ru.NR₃ (R = alkyl/H) was isolated from stoichiometric reactions of 1 or 2 with primary and secondary amines. It was found that tertiary amines do not generate complexes of the above type but rather unexpectedly give secondary amine complexes by cleavage of an alkyl group. The only isolatable tertiary amine complex is the moderately stable (CPD)(CO)₂RuNMe₃. All amine complexes were characterized by spectral and elemental analyses. Catalytic aspects of C-N bond cleavage were studied. Complexes (1) and (2) were found to react with primary, secondary and tertiary amines to generate imminium or eneamine species which subsequently undergo hydrolysis with water. This is in contrast to the Ru carbene mechanism previously proposed for cluster catalyzed C-N bond activation and cleavage. The two reactions are compared with respect to D for H exchange (with D₂O), water requirement and production of trace products during catalysis. A primary alcohol was found to substitute alkyl groups of a tertiary amine under the catalytic action of 1. A catalytic reaction cycle is proposed.     

An experimental and theoretical study on the effects of amine chain length on CO2 absorption performance

To explore the effect of amine chain length on CO₂ absorption performance, the reaction kinetics of CO₂ absorption in aqueous 1-dimethylamino-2-propanol (DMA2P), 1-diethylamino-2-propanol (DEA2P), 2-(methylamino)ethanol (MAE), and 2-(ethylamino)ethanol (EAE) solutions with different concentrations were explored using the stopped-flow apparatus. Additionally, Density Functional Theory (DFT) calculations were conducted to examine the reaction mechanism and the free energy barrier of the elementary reactions underlying CO₂ absorption in these four aqueous amine solutions. Kinetic models for CO₂ absorption in tertiary amines and secondary amines were established, based on the base-catalyzed hydration mechanism and the zwitterion mechanism, respectively, both of which perform well in predicting the relationship between k₀ and the amine concentration. The free energy barrier obtained by DFT is consistent with the activation energy barrier trend obtained by experiment. In addition, the effect of chain length on the free energy barrier was investigated through the chemical bond and weak interaction analysis.     

A method of obtention of N substituted quaternary ammonium salts supported by a polymeric chain

Summary Starting from tertiary amine polymers the reaction can be written in two steps 1) quaternization of the amine group by acid halide 2) addition of an electrophylic ethylenic reagent on the quaternary ammonium salt : X^– is Cl^– or is the tertiary amine supported by the polymers. Tertiary amine group tested are : pyridine, pyrazine, quinoleine, quinoxaline and N dimethyl phenyl. Z is an attracting group as :     

A GC–MS study of the addition reaction of aryl amines with acrylic monomers

Previous studies have shown that the interaction of carboxylic acid groups with the amine functionalities of aryl amines, especially secondary and tertiary aryl amines, can lead to the free-radical polymerization of acrylic monomers such as methyl methacrylate. In this study, the Michael addition reaction of primary and secondary aryl amines with acrylic monomers such as acrylic acid (AA) was investigated. Equivalent amounts of either p-toluidine (PT) or N-phenylglycine (NPG) and AA were combined in polar solvents such as ethanol. The reactions were conducted at ambient (23°C) or near-ambient (37–60°C) temperatures. Samples (about 3–5 mg) of these products were then trimethylsilylated with a solution consisting of 0.4 mL of bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 0.4 mL of acetonitrile by heating for 30 min at 140°C under N₂. These derivatives were characterized by gas chromatography–mass spectrometry (GC–MS). The GC–MS analyses suggest that 1 mol of the primary amine PT had reacted with 2 mol of AA to yield the expected N-p-tolyliminodipropionic acid. Similarly, the secondary amine NPG added to 1 mol of AA yielded the corresponding mixed iminodiacid, N-phenyliminoacetic–propionic acid. It would appear that the Michael reaction of primary and secondary amines with acrylic monomers may offer a general, facile synthetic route to a variety of tertiary amines. Aryl amino acids of the type synthesized in this study may find use in a number of dental applications, e.g., as surface-active adhesive agents and as polymerization initiators or activators. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 67:1545–1551, 1998     

α‐Bis and α,ω‐tetrakis(4‐dimethylaminophenyl) functionalized polymers by atom transfer radical polymerization using 1,1‐bis[(4‐dimethylamino)phenyl]ethylene as tertiary diamine initiator precursor and functionalizing agent

The quantitative syntheses of α‐bis and α,ω‐tetrakis tertiary diamine functionalized polymers by atom transfer radical polymerization (ATRP) methods are described. A tertiary diamine functionalized 1,1‐diphenylethylene derivative, 1,1‐bis[(4‐dimethylamino)phenyl]ethylene (1), was evaluated as a unimolecular tertiary diamine functionalized initiator precursor as well as a functionalizing agent in ATRP reactions. The ATRP of styrene, initiated by a new tertiary diamine functionalized initiator adduct (2), affords the corresponding α‐bis(4‐dimethylaminophenyl) functionalized polystyrene (3). The tertiary diamine functionalized initiator adduct (2) was prepared in situ by the reaction of (1‐bromoethyl)benzene with 1,1‐bis[(4‐dimethylamino)phenyl]ethylene (1) in the presence of a copper (I) bromide/2,2′‐bipyridyl catalyst system. The ATRP of styrene proceeded via a controlled free radical polymerization process to afford quantitative yields of the corresponding α‐bis(4‐dimethylaminophenyl) functionalized polystyrene derivative (3) with predictable number‐average molecular weight (M_n) and narrow molecular weight distribution (M_w/M_n) in a high initiator efficiency reaction. The polymerization process was monitored by gas chromatography analysis. Quantitative yields of α,ω‐tetrakis(4‐dimethylaminophenyl) functionalized polystyrene (4) were obtained by a new post ATRP chain end modification reaction of α‐bis(4‐dimethylaminophenyl) functionalized polystyrene (3) with excess 1,1‐bis[(4‐dimethylamino)phenyl]ethylene (1). The tertiary diamine functionalized initiator precursor 1,1‐bis[(4‐dimethylamino)phenyl]ethylene (1) and the different tertiary amine functionalized polymers were characterized by chromatography, spectroscopy and non‐aqueous titration measurements. Copyright © 2012 Society of Chemical Industry     

Production of pharmaceuticals: Amines from alcohols in a continuous flow fixed bed catalytic reactor

This paper reports the use of an immobilised ruthenium complex in a continuous flow process for the N-alkylation of morpholine with benzyl alcohol. The ruthenium-based catalyst was supported on a phosphine bound polymer. Screening experiments were first performed in a batch reactor, with a 16 vol% mixture of morpholine and benzyl alcohol (stoichiometric molar ratio of 1:1) in toluene as the solvent. Operating at 110 °C for 24 h, it was shown that high conversions (>99%) into the desired tertiary amine could be achieved. This reaction was then shown to be viable in a continuous flow reactor, where the catalytic polymer beads were retained in the bed. Operating at 150 °C and using p-xylene as a solvent, the conversion into the desired tertiary amine was shown to be as high as 98%. This approach is clearly very promising, as it provides a greener and more atom efficient route for the production of secondary and tertiary amines in the pharmaceutical industry.     

In Situ Formed Bifunctional Primary Amine‐Imine Catalyst: Application to the Construction of Chiral Tertiary Alcohols through Asymmetric Aldol‐Type Reaction

An in situ formation method to obtain chiral bifunctional primary amine‐imine catalysts from the C₂‐symmetric chiral diimines has been developed. The efficiency of this method in the construction of chiral tertiary alcohols which are valuable pharmaceutical intermediates is proved by its application to the asymmetric aldol‐type reaction of cyclic ketones with other activated ketone compounds as the enamine acceptors, i.e., β,γ‐unsaturated α‐keto esters and isatins. In general, good to excellent diastereoselectivities and enantioselectivities (up to 96/4 dr, 96% ee for β,γ‐unsaturated α‐keto esters and up to 91/9 dr, 94% ee for isatins) were obtained. The active primary amine‐imine catalylst and enamine intermediate in the reaction process could be demonstrated by ESI‐MS analysis.     

Efficient Allylation of Nucleophiles Catalyzed by a Bifunctional Heterogeneous Palladium Complex‐Tertiary Amine System

We demonstrate the synergistic catalysis of a silica‐supported diaminopalladium complex and a tertiary amine (SiO₂/diamine/Pd/NEt₂) as well as synthetic scope of the Tsuji–Trost reaction of 1,3‐dicarbonyls, phenols, and carboxylic acids with allyl carbonate and acetates. The synergistic catalysis of SiO₂/diamine/Pd/NEt₂ exhibited wide applicability and high activity for the Tsuji–Trost reaction. For example, the reaction of ethyl 3‐oxobutanate with allyl methyl carbonate afforded the allylated product in >99% yield at 70 °C for 5 h. The yield of allylated products was 26% for SiO₂/diamine/Pd, without immobilization of the tertiary amine group. In the reaction of 1.0 mmol of ethyl 3‐oxobutanate using 0.60 μmol of Pd in SiO₂/diamine/Pd/NEt₂, the turnover number (TON) of Pd reached up to 1070 within 24 h. Phenols with electron‐withdrawing groups, such as nitro and chloro groups, on the para position resulted in high product yields. The SiO₂/diamine/Pd/NEt₂ catalyst was reusable at least 4 times without appreciable loss of its activity and selectivity in the reaction of p‐chlorophenol.     

Latexes of starch-based graft polymers containing polymerized acrylonitrile

The scope of graft reactions to produce starch-based latexes was extended by graft polymerization of acrylonitrile (AN) onto gelatinized cationic starch possessing quaternary amine functionality and by graft terpolymerization of AN and t-butylaminoethyl methacrylate (TBAEM) onto gelatinized starch by cerium (IV) initiation at 25°C. Grafting onto starches containing highly basic quaternary amines gave polyacrylonitrile [poly(AN)] grafts having about one fourth the number-average molecular weight (M?_n) (178,000–232,000) of those produced by grafting AN onto starches containing the less basic tertiary amine groups. Sonification at 20 KHz of graft polymerization reaction mixtures having up to 8% solids reduced viscosities from 400–3000 cP to 10–40 cP. Diameters of dried particles measured about 300–1500 Å. Shaker-type agitation during grafting onto starch having quaternary amine groups produced poly(AN) chains with lower M?_n values than those produced during blade stirrer-type agitation. M?_n values of grafted poly(AN) decreased with increasing reaction time, degree of substitution of amine in the starch, gelation time of cationic starch at 95°C, and cerium (IV) concentration. AN was copolymerized with TBAEM at molar ratios of 14–85:1 in grafting onto gelatinized starch to yield copolymer side-chain grafts analyzing 8–52:1 of polymerized AN to TBAEM moieties.     

The development of kinetics model for CO2 absorption into tertiary amines containing carbonic anhydrase

CO₂ absorption into aqueous solutions of two tertiary alkanolamines, namely, MDEA and DMEA with and without carbonic anhydrase (CA) was investigated with the use of the stopped‐flow technique at temperatures in the range of 293–313 K, CA concentration varying from 0 to 100 g/m³ in aqueous MDEA solution with the amine concentration ranging from 0.1 to 0.5 kmol/m³, and CA concentration varying from 0 to 40 g/m³ in aqueous DMEA solution with the amine concentration ranging from 0.05 to 0.25 kmol/m³. The results show that the pseudofirst‐order reaction rate (k_{0, amine}; s^?1) is significantly enhanced in the presence of CA as compared with that without CA. The enhanced values of the kinetic constant in the presence of CA has been calculated and a new kinetics model for reaction of CO₂ absorption into aqueous tertiary alkanolamine solutions catalyzed by CA has been established and used to make comparisons of experimental and calculated pseudo first‐order reaction rate constant (k_{0, with CA}) in CO₂‐MDEA‐H₂O and CO₂‐DMEA‐H₂O solutions. The AADs were 15.21 and 15.17%, respectively. The effect of pKa on the CA activities has also been studied by comparison of CA activities in different tertiary amine solutions, namely, TEA, MDEA, DMEA, and DEEA. The pKa trend for amines were: DEEA > DMEA > MDEA > TEA. In contrast, the catalyst enhancement in amines was in the order: TEA> MDEA> DMEA> DEEA. Therefore, it can be seen that the catalyst enhancement in the amines decreased with their increasing pKa values. © 2017 American Institute of Chemical Engineers AIChE J, 2017     

Kinetics of carbon dioxide reaction with diethylaminoethanol in aqueous solutions

Differential rates of CO₂ adsorption into 0.90, 0.47 and 0.24 M aqueous solutions of 2-(diethylamino)ethanol (DEAE) were measured at 323 K over a wide range of carbonation ratios. A rigorous thermodynamic model was used to define species activities which were coupled with Danckwerts' gas-liquid reaction model to deduce the kinetics. The reaction of CO₂ with this highly basic tertiary amine occurs by two pathways: (1) a minor path via the CO₂ reaction with hydroxide ion and (2) a predominant reaction pathway that can be characterized by its first order dependency on the free amine concentration. The second reaction was proposed to involve an internal salt-like intermediate,.     

Etherification versus amine addition during epoxy resin/amine cure: An in situ study using near-infrared spectroscopy

The reactions between a multifunctional epoxy resin, tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM) and a monofunctional amine, methylaniline (mAnil) are studied. Due to the existence of a tertiary amine catalytic center within the TGDDM molecule, the etherification reaction during cure of TGDDM is usually more significant than in other epoxide systems. The importance of this reaction relative to the amine addition reactions is investigated. In situ near-infrared spectroscopy is used to obtain kinetic data during the cure reactions. The reaction rate constants are calculated from linear regression analysis for both amine addition and etherification reactions based on the reaction mechanisms proposed. Arrhenius relationships are observed for all the reaction rate constants involved. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:895–901, 1998     

Extraction Equilibria of Butyric Acid with Organic Solvents

Abstract

Fourteen solvents (five with a tertiary amine and different diluents, four C8-C18 alcohols, dibutylether, two hydrocarbons, and two vegetable oils) have been tested for the extraction of butyric acid. The highest distribution coefficient for butyric acid is shown by solvents with tertiary amines. A ternary solvent with amine extractant, n-alkanes as diluent, and higher alcohol as modifier can be advantageous in this procedure. Amines enable the extraction of acid at a pH above the pK _a value up to about pH 5.6. With an increase of the molecular weight of alcohol, the value of the distribution coefficient decreases. Its value for pure alcohols is independent of the concentration of acid in the aqueous phase. Equilibrium data suggest that the stoichiometry of the acid-alcohol complex is 2:1, and only undissociated acid is extracted.     

Copper–amine complexes as new catalysts for rigid polyurethane foam preparations

A new class of catalyst for the preparation of rigid polyurethane (RPUR) foams was developed. Metal(II)–amine complexes [M(en)₂ and M(trien), where M = Cu or Ni, en = ethylenediamine, and trien = triethylenetetramine] were synthesized and used as catalysts in the preparation of RPUR foams. The catalytic activity of the metal(II)–amine complexes and properties of the RPUR foams were investigated and compared to those prepared by N,N‐dimethylcyclohexylamine (DMCHA), which is a common commercial tertiary amine catalyst used in the preparation of RPUR foams. The use of M(en)₂ and M(trien) can improve the working environment in RPUR foam processing because DMCHA and other commercial tertiary amine catalysts have a strong odor, whereas M(en)₂ and M(trien) do not have any odor. The reaction times in RPUR foam preparation, namely, cream time, gel time, tack‐free time, and rise time, were investigated. These data indicated that the copper–ethylenediamine complex [Cu(en)₂] and copper–triethylenetetramine complex [Cu(trien)] had comparable catalytic activity to DMCHA, whereas the catalytic activity of the nickel complexes was not good. Attenuated total reflection–IR spectroscopy of the RPUR foams prepared with Cu(en)₂ and Cu(trien) showed quantitative isocyanate (NCO) conversion. The density and compressive strength of the RPUR foams prepared from Cu(en)₂ and Cu(trien) were comparable to those prepared from DMCHA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012