Application of Crown Ether to Chemical Analysis. III. Extraction of Amines with Crown Ether

Abstract

The protonated amines were extracted with crown ether as the picrate into organic solvent. The overall extraction constants(Kex) for the 1 : 1 : 1 complexes, AHLP, of 18-crown-6 with protonated amines and picrate between 1,2-dichloroethane and water have been determined at 25°C. The extractability of complexes decreased in the sequence: primary amines > secondary amines, which indicated that the type of amine was a most important factor. The log Kex values were determined to be 6.6, 7.6, 7.9, 8.3, 9.6, 2.5 and 3.8 for tert-butylamine, ethylamine, n-butylamine, sec-butylamine, n-hexylamine, diethylamine and di-n-propylamine respectively.     

Catalytic N-Alkylation of Amines with Aldehydes by a Molecular Mo Oxide Catalyst

Secondary and tertiary amine derivatives are very important in chemical and pharmaceutical industries. The N-alkylation of amines with aldehydes is a proper way to form secondary and tertiary amines. However, the traditional catalyst systems for this transformation bring a series of problems such as narrow substrate scope, challenges of difficult catalyst preparation and metal residues and toxicity. Herein an efficient way to perform N-alkylation of amines with aldehydes was described which used a molecular Mo oxide catalyst. In this pathway, various aldehyde and amine derivatives were successfully converted to the corresponding secondary and tertiary amines with high selectivity and efficiency. In addition, the catalyst was easy to prepare, and could be recycled six times without appreciable loss of conversion. Finally, the reaction mechanism was presented based on the observation of the possible intermediates and control experiments.     

Photostabilizing activity of tertiary hindered amines

The influence of the N-alkyl group of tertiary hindered amines on the photostabilization of polymers was studied. The photostabilizing effects of the tertiary amine derivatives of 4-benzoyloxy-2,2,6,6-tetramethylpiperidine ( 1a ) in polypropylene were compared. All tertiary amine derivatives having α-H to hindered N showed higher effectiveness than 1a . Model liquid phase photoxidations were carried out by irradiating (UV-lamp) the solutions of tertiary hindered amines containing tert-butyl hydroperoxide as a photoinitiator. The tertiary hindered amines were oxidized more easily than corresponding parent hindered amine and converted to the parent amine, which was identified as its salt, resulting from the carboxylic acid produced from the N-alkyl group by oxidation. The thermal reaction of the tertiary hindered amines with tert-butyl hydroperoxide was also studied in the liquid phase. The tertiary hindered amines decomposed tert-butyl hydroperoxide more rapidly than the parent secondary hindered amine, and generated the parent amine. It was also found that the photostabilizing effects of tertiary hindered amines for polyolefins were higher than that of the parent secondary hindered amine.     

Vinyl Polymerization 204. Initiation Mechanism of the Radical Polymerization of Vinyl Monomers by p-Methoxy -p'-nitrobenzoyl Peroxide and Tertiary Amines

Abstract

A study of the reaction of tertiary amines with p-methoxy-p'-nitrobenzoyl peroxide in the presence of styrene was made in benzene. Anisic acid and p-nitrobenzoic acid were obtained from the reaction product. Using gas chromatography, the molar ratio of the amount of the above two acids was measured and classified into three types, according to the kind of amine used. From the results the reaction mechanism was discussed, and it was concluded that the oxygen which stands adjacent to the p-methoxybenzoyl group may be charged more positively and may be the more predominantly attacked by tertiary amine.     

Safe and Efficient Reductive Methylation of Primary and Secondary Amines Using N-Methylpyrrolidine Zinc Borohydride

An efficient, general procedure for reductive methylation of primary and secondary amines with 37% formaldehyde using N-methylpyrrolidine zinc borohydride (ZBHNMP) as a reducing agent gave the corresponding tertiary amines in excellent yields. The reaction was carried out in tetrahydrofuran under neutral conditions at 0–10 °C.     

HPLC Laser Fluorometric Determination of Amines in Beer

Abstract

A method has been developed for the rapid and accurate determination of the predominant aliphatic amines in beer. Chromatography was performed on a reverse phase C₁₈ column using an acetonitrile-water solvent gradient. Chromatographic detection was facilitated by pre-column derivatization with 7-Chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) which fluoresces under visible light (in this case an argon ion laser operating at 488 nm) after reaction with an amine. Response was linear over four decades of concentration with detection limits at approximately five picograms injected.     

Simultaneous spectrophotometric analysis of aliphatic amines utilizing thermochromism of charge-transfer complexes with tetrabromophenolphthalein ethyl ester.

Aliphatic amines, such as n-hexylamine (primary), di-n-hexylamine (secondary) and tri-n-hexylamine (tertiary amine), react with tetrabromophenolphthalein ethyl ester molecules (TBPEH) to form reddish or red-violet charge-transfer complexes (CT complexes) in 1,2-dichloroethane (DCE). The absorption maxima of the CT complexes with all primary amines occur at around 560 nm, with secondary amines at 570 nm and, with tertiary amines at 580 nm. The CT complex formation constants with TBPEH in DCE increase in the order of the primary, secondary and tertiary amines, but their constants decrease quantitatively with an increase in temperature. This phenomenon (thermochromism) could be applied to the simultaneous spectrophotometric determination of primary amine and secondary amine, or secondary amine and tertiary amine in a mixed solution utilizing the difference of absorbance with temperature changes.     

LC Determination of Trace Biogenic Amines in Foods Samples with Fluorescence Detection and MS Identification

A pre-column derivatization method for the simple, sensitive determination of biogenic amines using 10-ethyl-acridine-3-sulfonyl chloride (EASC) as labeling reagent with fluorescence detection and mass spectrometry (MS) identification has been developed. After pre-column derivatization, the labeled biogenic amines were separated on a Hypersil BDS-C18 column by gradient elution. The derivatives showed an intense protonated molecular ion corresponding m/z [M + H]⁺ in positive-ion mode. The collision-induced dissociation of protonated molecular ion formed specific fragment ions at m/z 196.5, m/z 222.7, m/z 224.4 and m/z 272.5, m/z 286.2. Satisfactory linear responses were observed at the concentration range of 0.02?C10 ??mol L^?1 with coefficients of >0.9993. Detection limits obtained by the analysis of a derivatized standard containing 0.2 pmol of each biogenic amine, were from 20.22 to 109.2 fmol (at a signal-to-noise ratio of 3). The relative standard deviations of retention times and peak areas for each biogenic amine were <0.96 and 3.22%, respectively. Recoveries except for PUT were in the range of 96.7?C103.6% for chicken sausage and 95.8?C104.6% for pork sausage The established method for the determination of biogenic amines except for PUT from real samples was satisfactory.     

A Simple Simultaneous Colorimetric Determination of Primary and Secondary Amines with Fluorescamine

Abstract

Primary and secondary amines react reproducibly with fluorescamine to form pyrrolinones or aminoenone type chromophores with long wavelength absorption maxima in the 375–410 and 310–320 nm regions, respectively. A simple procedure has been worked out for the simultaneous colorimetric determination of primary and secondary amines.     

NBD-Cl as a Post-Column Reagent for Primary and Secondary Amines after Separation by Ion-Exchange Chromatography

In this study 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) is proposed as a post-column derivatization (PCD) reagent for the fluorescence detection of aliphatic primary and secondary amines after HPLC separation. Five primary (methylamine, isoamylamine, 2-phenylethylamine, putrescine, and histamine) and one secondary amine (dimethylamine) were separated isocratically on a cation-exchange column using HNO₃ (5 × 10^?3 mol L^?1) as the mobile phase. Post-column derivatization was based on two steps: 1) the derivatization of amines with NBD-Cl in alkaline medium, and 2) the acidification of the resulted mixture in order to minimize the background signal of the reagent and improve dramatically the sensitivity and determination range. The variables of the post-column reaction (concentration of NBD-Cl, buffer concentration and pH, reaction temperature, concentration of HCl, flow rates of the reagents) were thoroughly investigated. Critical chromatographic parameters such as the concentration of HNO₃, the percentage of organic solvent, and the column temperature were also examined to achieve adequate separation. An internal standard of 1,7-diaminoheptane was used. The developed post-column method provides the ability for a fully automated analysis, low detection limits (LODs 20–100 µg L^?1 with S/N = 3), and it requires less sample preparation. The applicability of the proposed analytical scheme was demonstrated by the determination of histamine (HIS) in tuna fish tissues according to US Food and Drug Administration (FDA) guidelines.     

An HPLC Method for the Determination of Amines in Flotation Pulp Based on Derivatization

Alkyl amines are surfactants used as quartz collectors in the reverse flotation of phosphate ores. It is important in both research and industrial practice to quantify amine concentration in the solution and/or wastewater. A simple and rapid method using high-performance liquid chromatography (HPLC) was developed to quantitatively determine the concentration of amine collectors (including dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine) in a mineral flotation system. The method involved a sample derivatization procedure with 9-fluorenyl methoxycarbonyl chloride (FMOC-Cl) and separation/determination by HPLC coupled with a fluorescence detector. The calibration curves showed good linearity (R²?>?0.9956) in the range of 0.20–5.00 µg/mL, and the recoveries of dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine were in the ranges of 84.93–97.64%, 89.93–101.92%, 85.29–98.37%, and 93.57–103.26%, respectively. The method was successfully used to quantify amines in wastewater from flotation experiments and artificial flotation wastewater (amine solution after activated carbon adsorption). The results from the analysis of four amines in the solution demonstrated that the proposed method is suitable for the simultaneous determination of amines in flotation pulp and wastewater.

     

Determination of Biogenic Amines in Digesta by High Performance Liquid Chromatography with Precolumn Dansylation

A rapid high-performance liquid chromatographic method for the determination of nine biogenic amines in digesta sample from pig cecum and colon was developed using a simple direct derivatization with dansyl chloride. After precipitation with trichloroacetic acid and extraction by n-hexane, the amines were separated on a C₁₈ column using a water–acetonitrile gradient elution program. The calibration curve for each amine was linear over the range of 50 to 250 µmol/L, and the relative standard deviation for intra-assay precision was below 0.5%. The recovery ranged from 86.79% to 117.62% while the limit of detection was 0.1 µmol/L for the amines except for spermine with a value of 0.03 µmol/L. This procedure was successfully applied to identify and quantify biogenic amines in the hindgut digesta of the pig.     

Pt-Sn/γ-Al2O3-catalyzed highly efficient direct synthesis of secondary and tertiary amines and imines

Versatile syntheses of secondary and tertiary amines by highly efficient direct N‐alkylation of primary and secondary amines with alcohols or by deaminative self‐coupling of primary amines have been successfully realized by means of a heterogeneous bimetallic Pt–Sn/γ‐Al₂O₃ catalyst (0.5 wt % Pt, Pt/Sn molar ratio=1:3) through a borrowing‐hydrogen strategy. In the presence of oxygen, imines were also efficiently prepared from the tandem reactions of amines with alcohols or between two primary amines. The proposed mechanism reveals that an alcohol or amine substrate is initially dehydrogenated to an aldehyde/ketone or NH‐imine with concomitant formation of a [PtSn] hydride. Condensation of the aldehyde/ketone species or deamination of the NH‐imine intermediate with another molecule of amine forms an N‐substituted imine which is then reduced to a new amine product by the in‐situ generated [PtSn] hydride under a nitrogen atmosphere or remains unchanged as the final product under an oxygen atmosphere. The Pt–Sn/γ‐Al₂O₃ catalyst can be easily recycled without Pt metal leaching and has exhibited very high catalytic activity toward a wide range of amine and alcohol substrates, which suggests potential for application in the direct production of secondary and tertiary amines and N‐substituted imines.     

Quenching of O2(1Δg) by aliphatic amines

The quenching rate constants of O₂(¹Δ_g) with n-butylamine, diethylamine, dipropylamine, dibutylamine, and tripropylamine have been determined in a discharge flow system. The rate constants are found to be (1.6 ± 0.2) × 10³, (8.5 ± 0.6) × 10⁴, (9.8 ± 0.5) × 10⁴, (2.1 ± 0.1) × 10⁵, and (8.6 ± 0.5) × 10⁵ 1 mol^?1 s^?1, respectively. The rate constants are found to increase in the order, tertiary amine → secondary amine → primary amine. The “inductive effect” of alkyl substitution is also found to increase the rate constant in a given series of amines.     

Development of a General Non‐Noble Metal Catalyst for the Benign Amination of Alcohols with Amines and Ammonia

The N‐alkylation of amines or ammonia with alcohols is a valuable route for the synthesis of N‐alkyl amines. However, as a potentially clean and economic choice for N‐alkyl amine synthesis, non‐noble metal catalysts with high activity and good selectivity are rarely reported. Normally, they are severely limited due to low activity and poor generality. Herein, a simple NiCuFeO_x catalyst was designed and prepared for the N‐alkylation of ammonia or amines with alcohol or primary amines. N‐alkyl amines with various structures were successfully synthesized in moderate to excellent yields in the absence of organic ligands and bases. Typically, primary amines could be efficiently transformed into secondary amines and N‐heterocyclic compounds, and secondary amines could be N‐alkylated to synthesize tertiary amines. Note that primary and secondary amines could be produced through a one‐pot reaction of ammonia and alcohols. In addition to excellent catalytic performance, the catalyst itself possesses outstanding superiority, that is, it is air and moisture stable. Moreover, the magnetic property of this catalyst makes it easily separable from the reaction mixture and it could be recovered and reused for several runs without obvious deactivation.     

LC Analysis of Histamine and Other Biogenic Amines in Digesta Cultures

In the intestine, microbial protein degradation to histamine and other biologically active amines is believed to be relevant to the health of species. An LC method with fluorescence detection has been developed for analysis of histamine, phenylethylamine, isoamylamine, putrescine, cadaverine, tyramine, and spermidine. After pre-column derivatisation with 9-fluorenylmethyl chloroformate, amines were separated on a reversed-phase C₁₈ polyamine column with a mobile phase gradient. Validation of the method included calibration experiments, determination of amine recovery, and repeatability tests. The method proved especially useful for detection of histamine, phenylethylamine, putrescine, and cadaverine at relevant concentrations in caecum cultures from horses. The limits of quantification for these four amines ranged between 80 nM (histamine) and 400 nM (phenylethylamine).     

Trans ligand influence in cobalt(III) Schiff base complexes: Electronic and steric effects on the kinetics of hydrolysis

Rate constants for the hydrolysis (k_h) of six different amines in trans‐[Co((BA)₂en)(amine)₂]ClO₄ complexes (amine = aniline 1a , para‐toluidine 1b , benzylamine 1c (primary amines), pyrrolidine 2a , piperidine 2b , morpholine 2c (secondary amines), and (BA)₂en = Bisbenzoylacetoneethylenediiminato) in mixed methanol/water (1:1) solvent have been determined between 30 and 55°C. The hydrolysis product of 2c , trans‐[Co((BA)₂en)(morpholine)(H₂O)]ClO₄, has been separately prepared and characterized by UV–vis and ¹H NMR spectroscopy. Depending on the nature of the axial amine ligand the limiting first‐order rate constants for the amine hydrolysis at 40°C range from (3.42 ± 0.10) × 10^?5 to (5.32 ± 0.13) × 10^?5 s^?1. At the first glance, a reasonable trend cannot be established between k_h and the basicity or the inductive trans effect of the amine ligands. However, when the complexes are classified into two groups, based on the type of the amine (primary and secondary), the values of k_h correlate well with the basicity or inductive effect of the amine in each group. The observed trend in k_h values for the complexes with primary amines is 1a (5.32 ± 0.13) × 10^?5 s^?1 > 1b (3.51 ± 0.14) × 10^?5 > 1c (1.72 ± 0.03) × 10^?5 (40°C), which is opposite to the amine basicity strength. In the case of the complexes with secondary amines, the observed trend in k_h values is in accord with amine basicity (or inductive trans effect), i.e. 2a (5.02 ± 0.22) × 10^?5 > 2b (4.18 ± 0.10) × 10^?5 > 2c (3.42 ± 0.10) × 10^?5 s^?1 (40°C). © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 387–393, 2002     

Derivatizat Ion of Primary Aromatic Amines with Fluorescamine

Abstract

Fluorescamine forms stable, fluorescent derivatives with sterically-unhindered primary aromatic amines in both aqueous (borate buffer, pH 9/acetonitrile) and nonaqueous (pyridine/-acetonitrile) media. Aromatic amines with a substituent such as a methyl group or an aromatic ring ortho to the amine functionality either derivatized poorly or not at all because of steric hindrance.     

Gold Trace Separation from some Platinum Group Metals on Cationic Exchanger in the Presence of Amines

Abstract

The sorption behaviour of gold in the presence of amines on different kinds of cationic exchangers with phosphonic groups has bee investigated. The system Cellex P - amine has been found very useful for gold separation from platinum metals. The method was adopted for trace gold determination in PdC1₂ and platinum powder.     

Discrimination of Primary Amines from Other Fluorescent Compounds in Biological Fluids

Abstract

Experimental condition and parameters involved in HPLC distinction of primary amines from non-primary amine compounds with native fluorescence were investigated. The discrimination conditions were designed to enable utilization of the sensitive reagent fluorescamine as a means of monitoring primary amines in physiologic fluids.