Basic Aromatic Amines Research Articles

Coupling coloration of meta‐aramid fabric utilising diazonium salts from weakly basic aromatic amines

AbstractMeta‐aramid fibre exhibits poor dyeing performance when treated using conventional dyeing methods. In this study, coloration of meta‐aramid fabrics was performed at room temperature utilising diazonium salts from weakly basic aromatic amines and was achieved via in situ construction of azo chromophores on the meta‐phenylenediamine moiety. To promote diazonium‐salt penetration into the meta‐aramid fibre, the pretreatment of meta‐aramid fabrics with dimethyl sulfoxide at 55°C for 30 min and the utilisation of methanol were involved during the coloration process. As a result, the fabrics could be coloured with deep, levelled and firm shades of brown series. The azo chromophore is derived from the skeleton of the polyamide chain. Therefore, the coloured fabrics exhibit good resistance to organic solvents as well as good to excellent colour fastness to soaping, rubbing and sublimation. A study of the coloration mechanism revealed that the terminal and middle meta‐phenylenediamine moieties serve as the main coupling reaction sites. When treated with a diazonium salt, the highly reactive terminal meta‐phenylenediamine moiety reacted first and generated chromophores with an absorption peak in the long‐wavelength region. However, such chromophores only contributed a limited colour depth owing to the limited number of the terminals. If excess diazonium salts were used, the main hue can be attributed to the azo chromophores based on the massive middle meta‐phenylenediamine moieties, although these moieties are less reactive than the terminal meta‐phenylenediamine moieties.

Continuous-Flow Diazotization of Weakly Basic Aromatic Amines in a Microreaction System

Due to the characteristics of high transfer efficiency, controllable process, and intrinsic safety in microreactors, there have been many studies on the miniaturization of diazotization reactions. However, diazotization of weakly basic aromatic amines is difficult to be reformed by continuous microreaction technology due to its poor solubility. In this paper, first, by improving the crystallization process, the miniaturization of diazotization with low solid content was realized. The effects of various parameters (flow rate, temperature, reagent dosage, and concentration) on the reaction yield were investigated systematically. As for high solid content, by introducing the gas–liquid Taylor flow and ultrasonic assistance, the mass transfer process was strengthened, and the slurry flow pattern was improved. Finally, at 0.40 mol/L, a residence time of 94 s in the delay loop with a 5 °C cold trap was employed to produce a diazonium salt in 96% yield with high stability.

Dual Activation of Carboxylic Acid Functionality by Protic Ionic Liquid: Solvent and Metal Free Strategy for Selective Esterification of Alcohols and Acylation of Aromatic Amines

AbstractHighly efficient and chemoselective esterification of alcohols and acylation of aromatic amines with carboxylic acids using imidazolium based protic ionic liquid, 1‐butyl‐imidazolium trifluoroacetate ([HBIm]TFA) as activator has been realized under organic volatile solvent free condition. The protic ionic liquid played dual role for activation of carboxylic acid which was proved by NMR study. A very interesting aspect of the present protocol is the acylation of less basic aromatic amines than the more reactive aliphatic amines as the later one forms salt with carboxylic acid. Our methodology offers several advantages like high yield, fast, efficient, chemo‐selectivity, metal and other coupling agent free procedure, recyclability of ionic liquid used and formation of water as the only by‐product.

Exploration of the carmaphycins as payloads in antibody drug conjugate anticancer agents

Antibody–drug conjugates (ADCs) represent a new dimension of anticancer chemotherapeutics, with warheads to date generally involving either antitubulin or DNA-directed agents to achieve low-to sub-nanomolar potency. However, other potent cytotoxins working by different pharmacological mechanisms are under investigation, such as α,β-epoxyketone based proteasome inhibitors. These proteasome active agents are an emerging class of anticancer drug that possesses ultra-potent cytotoxicity to some cancer cell lines. The carmaphycins are representatives of this latter class that we isolated and characterized from a marine cyanobacterium, and these as well as several synthetic analogues exhibit this level of potency. In the current work, we investigated the use of these highly potent cytotoxic compounds as warheads in the design of novel ADCs. We designed and synthesized a library of carmaphycin B analogues that contain amine handles, enabling their attachment to an antibody linker. The basicity of these incorporated amine handles was shown to strongly affect their cytotoxic properties. Linear amines resulted in the greatest reduction in cytotoxicity whereas less basic aromatic amines retained potent activity as demonstrated by a 4-sulfonylaniline derivative. These investigations resulted in identifying the P2 residue in the carmaphycins as the most suitable site for linker attachment point, and hence, we synthesized a highly potent analogue of carmaphycin B that contained a 4-sulfonylaniline handle as an attachment point for the linker antibody.

Facile Fabrication of Polymeric Ionic Liquid Grafted Porous Polymer Monolith for Mixed‐Mode High Performance Liquid Chromatography

AbstractA novel polymeric ionic liquid grafted porous polymer monolith has been facilely fabricated for mixed‐mode chromatography. The column is prepared from poly (glycidyl methacrylate‐co‐ethylene dimethacrylate) monolith through hydrolyzation of the epoxy moieties into hydroxyl groups, followed by "grafting from" polymerization of ionic liquid of 1‐vinyl‐3‐butylimidazolium chloride. Successful modification is characterized by scanning electron microscope, infrared spectroscopy, elemental analysis and mercury intrusion porosimetry. The HPLC performance of developed column is evaluated by separating acidic vitamin B analytes, neutral steroids and basic aromatic amines in mixed‐mode chromatography on a single column, respectively. The ionic liquid affords the monolith with both enhanced separation ability and improved column efficiency.

Glycosylation of aromatic amines III: Mechanistic implications of the pH-dependent glycosylation of various aromatic amines (kynurenine, 2′-aminoacetophenone, daptomycin, and sulfamethoxzaole)

Glycosylation reaction kinetics of a series of aromatic amines (kynurenine, 2′-aminoacetophenone, daptomycin, and sulfamethoxazole) was compared to propose a unifying reaction mechanism. Kinetic studies were conducted in aqueous solutions containing glucose in the pH range 1–6.5 with 2′-aminoacetophenone and daptomycin. The resultant pH-rate profiles were compared to previously reported profiles for the reactions of glucose and kynurenine or sulfamethoxazole. Glycosylation of weakly basic aromatic amines involved the addition of the unprotonated amine to the aldehydic sugar leading to carbinolamine formation followed by specific acid catalyzed dehydration. All of the pH-rate profiles displayed characteristic downward bend at pH 4–5 due to a change from rate-determining addition to dehydration. In the pH-rate profile for kynurenine, a second downward bend was observed in the pH region 2–4. This feature was absent for the other substrates and was attributed to differences in reactivity of the two ionization states of the alpha carboxylic acid in kynurenine. This stabilization was not possible for the other amines studied. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:4639–4649, 2009

Preparation of monodispersed vinylpyridine–divinylbenzene porous copolymer resins and their application to high-performance liquid chromatographic separation of aromatic amines

For the separation of aromatic amines, two types of monodispersed porous polymer resins were prepared by the copolymerization of 2-vinylpyridine and 4-vinylpyridine with divinylbenzene in the presence of template silica gel particles (particle size 5 μm), followed by dissolution of the template silica gel in an alkaline solution. The transmission electron micrographs and the scanning electron micrograph revealed that these templated polymer resins have a spherical morphology with a good monodispersity and porous structure. Using these monodispersed polymer resins, the high-performance liquid chromatographic separation of aromatic amines in the mobile phases of pHs 2.0, 2.9, 4.1, 7.2 and 11.7 were carried out. The 2-vinylpyridine–divinylbenzene copolymer resins showed slightly stronger retentions for aromatic amines than the 4-vinylpyridine–divinylbenzene copolymer resins. Under acidic conditions (around pH 2.0), aniline and the toluidines showed no retention on these copolymer resins due to the repulsion between the cationic forms of these amines and pyridinium cations in the stationary phase, whereas less basic aromatic amines or non-basic acetanilide showed slight retentions. Above pH 4.1, the separation of aromatic amines with these polymer resins showed a typical reversed-phase mode separation. Therefore, the separation patterns of aromatic amines are effectively tunable by changing the pH value of the mobile phases. A good separation of eight aromatic amines was achieved at pH 2.9 using the 2-vinylpyridine–divinylbenzene copolymer resins.

The synthesis of bi- and trichromophoric dyes bearing an s-triazinyl ring spacer

An alternative procedure has been described for the syntheses of several bi- and trichromophoric compounds consisting of 1-aminopyrene and 3-aminobenzanthrone chromophoric subsystems connected by an s-triazinyl ring spacer. The synthetic method used, which utilises an autoclave under autogenous pressure, is suitable for the nucleophilic substitution of both chlorine atoms within the triazinyl ring by weakly basic aromatic amines. The structures of the synthesized compounds were confirmed using elemental analysis, 1H NMR, and mass spectra. UV/vis absorption and fluorescence spectra and fluorescence quantum yields were measured. The dependence of fluorescence intensity and fluorescence quantum yields on solvent polarity was investigated.

ChemInform Abstract: Chemoselective Reductive Amination of Aldehydes and Ketones by Dibutylchlorotin Hydride-HMPA Complex.

Reductive amination of various aldehydes and ketones has been performed effectively by pentacoordinate chloro-substituted tin hydride complex, Bu2SnClH-HMPA. The tin reagent worked particularly well for the case using weakly basic aromatic amines as starting substrates. Stoichiometric amounts of a substrate and a reducing agent were adequate for the reaction. The Sn-Cl bond in the complex plays an important role for both steps of imine formation and subsequent reduction. Highly chemoselective reduction of carbonyls could be achieved regardless of other functionalities such as halogen, carbon-carbon double bond and hydroxyl groups in the starting carbonyls and amines.

Chemoselective Reductive Amination of Aldehydes and Ketones by Dibutylchlorotin Hydride-HMPA Complex

Reductive amination of various aldehydes and ketones has been performed effectively by pentacoordinate chloro-substituted tin hydride complex, Bu2SnClH-HMPA. The tin reagent worked particularly well for the case using weakly basic aromatic amines as starting substrates. Stoichiometric amounts of a substrate and a reducing agent were adequate for the reaction. The Sn-Cl bond in the complex plays an important role for both steps of imine formation and subsequent reduction. Highly chemoselective reduction of carbonyls could be achieved regardless of other functionalities such as halogen, carbon-carbon double bond and hydroxyl groups in the starting carbonyls and amines.

7H‐benz [kl]acridin‐7‐ylium closed‐shell ion produced from 1,8‐bis(phenylamino)naphthalenes under electron impact: Tandem mass spectrometric structure elucidation

AbstractNot only strongly basic aromatic amines such as ‘proton sponges’ show characteristic [M – Me2NH – H]+ peaks corresponding to cyclization to stable heterocyclic ions under electron impact. The fragmentation of the title compounds, which are weak bases, leads to [M – RNH2 – C6H5]+ heteroaromatic ions. These are the 7‐phenyl‐7H‐benz[kl]acridine radical cation and the delocalized stable 7H‐benz[kl]acridin‐7‐ylium ion as shown by unimolecular metastable ion spectra, collision‐induced decomposition (CID) tandem mass spectrometry (MS/MS) and accurate mass measurements. The high‐collision‐energy CID tandem mass spectra of these ions are perfectly superimposable on those of the ions produced by the reference substance, 7‐phenyl‐7H‐benz[kl]acridine obtained as a by‐product in the Ullmann phenylation of 1,8‐diaminonaphthalene. This combination of MS/MS experiments also provides strong support for the gas‐phase reaction mechanism leading to the benz[kl]acridine ions and for the structures of these ions.

Retention and selectivity in supercritical fluid chromatography on an octadecylsilyl-silica column

The changes in retention and selectivity of a series of model test compounds on an octadecylsilyl-silica column in supercritical fluid chromatography have been examined at different column pressures. The effects of the addition of modifiers to the carbon dioxide eluent have been compared using retention indices based on the alkyl aryl ketone scale. Without modifier, polar hydrogen-bonding analytes, such as alcohols and phenols, were highly retained, but their relative retention times were considerably reduced as the proportion of modifier increased. Aliphatic amines appeared to interact with free silanols on the surface on the stationary phase in the absence of modifiers and their retention changed markedly on the addition of small proportions of modifier. However, the relative retentions of more weakly basic aromatic amines were unaltered by modifier.

The Diazotization of Some Weakly Basic Aromatic Amines with Nitrosylhydrogensulfate in Sulfuric Acid

Journal für Praktische ChemieVolume 320, Issue 6 p. 1047-1054 Arbeitsvorschriften und Meßergebnisse Zur Diazotierung einiger schwach basischer aromatischer Amine mit Nitrosylhydrogensulfat in Schwefelsäure The Diazotization of Some Weakly Basic Aromatic Amines with Nitrosylhydrogensulfate in Sulfuric Acid Prof. Dr. G. Röbisch, Corresponding Author Prof. Dr. G. Röbisch Sektion Chemie/Biologie der Pädagogischen Hochschule “Karl Liebknecht”, DDR-15 Potsdam, Am Neuen PalaisSektion Chemie/Biologie der Pädagogischen Hochschule “Karl Liebknecht”, DDR-15 Potsdam, Am Neuen PalaisSearch for more papers by this authorDr. H. Süptitz, Dr. H. Süptitz Sektion Chemie/Biologie der Pädagogischen Hochschule “Karl Liebknecht”, DDR-15 Potsdam, Am Neuen PalaisSearch for more papers by this author Prof. Dr. G. Röbisch, Corresponding Author Prof. Dr. G. Röbisch Sektion Chemie/Biologie der Pädagogischen Hochschule “Karl Liebknecht”, DDR-15 Potsdam, Am Neuen PalaisSektion Chemie/Biologie der Pädagogischen Hochschule “Karl Liebknecht”, DDR-15 Potsdam, Am Neuen PalaisSearch for more papers by this authorDr. H. Süptitz, Dr. H. Süptitz Sektion Chemie/Biologie der Pädagogischen Hochschule “Karl Liebknecht”, DDR-15 Potsdam, Am Neuen PalaisSearch for more papers by this author First published: 1978 https://doi.org/10.1002/prac.19783200623Citations: 4AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume320, Issue61978Pages 1047-1054 RelatedInformation

ChemInform Abstract: REACTIONS OF PERFLUORO‐2,5‐DIMETHYL‐3,4‐HEXANEDIONE WITH AMINES

AbstractDie Titelreaktion liefert in guten Ausbeuten die 1:1‐Addukte (I), deren IR‐ und 19F‐NMR‐Daten tabellarisiert sind.

Reactions of Perfluoro-2,5-dimethyl-3,4-hexanedione with Amines

Abstract Perfluoro-2,5-dimethyl-3,4-hexanedione and aromatic or aliphatic amines gave the respective 1:1 adducts in good yields. With excess amounts of aliphatic amines or basic aromatic amines such as p-anisidine, the perfluorodiketone gave oxamides. With o-phenylenediamine, it gave 2,3-dihydroxyquinoxaline.

Basicity of aromatic amines from liquid chromatographic behavior

A liquid chromatographic investigation was conducted to determine whether the adsorption of weakly basic aromatic amines on slightly acidic silica gel adsorbents could be used to study their relative basicity. Under proper conditions, a linear correlation between pKb and log of capacity factor was observed. This finding may prove useful in helping to predict the relative basicity of closely related aromatic diamines, especially new amines being synthesized for polymer synthesis.

Reactions of N-heteroaromatic bases with nitrous acid. Part II. The kinetics of the diazotisation of 4-aminopyridine

The kinetics of the diazotisation of 4-aminopyridine have been studied in 0·0025–5·0M-perchloric acid. The reaction proceeds by one mechanism only, whose kinetic form is of first order with respect both to the amine and to nitrous acid.The rate of the reaction shows an exponential catalytic dependence on the concentration of added sodium perchlorate and a similar, but greater, catalytic dependence on perchloric acid. In solutions whose ionic strength is maintained constant by the addition of sodium perchlorate, the rate shows a linear dependence on the h0 function.These results are interpreted in terms of the reaction between the protonated amine and nitrous acidium ion. They are similar to the results observed in the nitrosation of the more basic aromatic amines in perchloric acid above ca. 1 M.

Chemistry of acetylenic ethers. XVIII: Reactions of ethoxyethynylcarbinols with amines

AbstractEthoxyethynylcarbinols, which can be prepared from carbonyl compounds and metallic derivatives of ethoxyacetylene, react with amines in three different ways.Strongly basic amines like diethylamine mainly cause reaction A, dissociation of the carbinol into the carbonyl compound from which the carbinol was derived, and ethoxyacetylene (which reacts further with the amine used). Very weakly basic aromatic amines like p‐nitroaniline catalyze the rearrangement into α,β‐unsaturated esters (reaction B), whereas aromatic amines like aniline yield amides of β‐hydroxy‐acids with evolution of ethylene (reaction C).