Ethylenediamine Condensation Research Articles

Intermolecular condensation of ethylenediamine to 1,4-diazabicyclo(2,2,2)octane over H-ZSM-5 catalysts: Effects of Si/Al ratio and crystal size

The intermolecular condensation of ethylenediamine (EDA) to 1,4-diazabicyclo [2.2.2] octane (DABCO) or triethylenediamine (TEDA) was conducted over H-ZSM-5 catalysts. The effects of reaction parameters, Al content and crystal size on the EDA condensation over H-ZSM-5 have been investigated. The H-ZSM-5 catalyst with a medium Al content (Si/Al = 110) and a small crystal size (ca. 100 nm) showed 99% EDA conversion and afforded a TEDA yield as high as 74% under optimized conditions. The mechanism for the H-ZSM-5-catalyzed condensation of EDA has also been considered. The framework Al-related Brønsted acid sites were assumed to contribute to selective intermolecular condensation of EDA to TEDA. The primary intermolecular condensation of EDA to piperazine (PIP) took place mainly inside the micropores of the MFI structure, while the secondary condensation of PIP with EDA to TEDA was favored by the acid sites located near the pore entrance and on the external surfaces of crystals.

Intermolecular condensation of ethylenediamine to 1,4-diazabicyclo[2,2,2]octane over TS-1 catalysts

The intermolecular condensation of ethylenediamine (EDA) to 1,4-diazabicyclo[2.2.2]octane or triethylenediamine (TEDA) has been carried out over various titanosilicate catalysts. Superior to Ti-MWW, Ti-Beta, Ti-FER, and Ti-MOR, TS-1 showed higher EDA conversion and TEDA selectivity. The effects of reaction parameters, Ti content, and crystal size on the EDA condensation over TS-1 have been investigated. The mechanism for the TS-1-catalyzed condensation of EDA has also been considered. The acid sites, originated from the Si–OH groups adjacent to the “open” Ti sites, were assumed to contribute to the intermolecular condensation of EDA, whereas the Lewis acid sites directly related to Ti(IV) ions were not the true active sites. The primary intermolecular condensation of EDA to 1,4-diazacyclohexane or piperazine (PIP) took place mainly inside the micropores of the MFI structure, while the secondary condensation of PIP with EDA to TEDA was favored by the acid sites located near the pore entrance and on the outer surface of crystals.

A fully automated HPLC method for the determination of catecholamines in biological samples utilizing ethylenediamine condensation and peroxyoxalate chemiluminescence detection.

A fully automated in-line extraction reversed-phase high-performance liquid chromatography (HPLC) method with chemiluminescence detection was developed for the analysis of human and rat plasma catecholamines (CAs), norepinephrine (NE), epinephrine (E) and dopamine (DA). N-Methyldopamine (N-MeDA) was used as an internal standard. The method involves collection of plasma samples, which are first diluted with a sample dilution buffer containing N-MeDA, and in-line extraction of CAs using a carboxylic acid small resin precolumn (SERUMOUT-CEX). This pre-extraction process was coupled with an HPLC system including reversed-phase mode separation on an analytical column (TSK gel ODS-80Ts), fluorogenic derivatization with ethylenediamine (ED) and finally postcolumn peroxyoxalate chemiluminescence reaction detection using bis [4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl]oxalate (TDPO) and hydrogen peroxide. The optimized mobile phase compositions, flow rates, operation timing for the adsorption and desorption of CAs in the precolumn, the separation in the analytical column and the optimum fluorogenic and chemiluminogenic reaction conditions were investigated. The detection limit for all the CAs was about 1 fmol (signal-to-noise ratio is 2). Excellent linearity of the calibration curves for CAs was observed in the range from 5 to 500 fmol for each CA using the internal standard. The relative standard deviations of the method for determining NE (183 fmol), E (23.6 fmol) and DA (6.1 fmol) in 50 microL of human plasma (n = 3) were 2.8, 2.7 and 3.1%, respectively, for the within-day assay and 5.0, 3.8 and 4.0%, respectively, for the between-day assay. The method was applicable to the determination of CAs in 25-50 microL of human or rat plasma.

Simple method for the simultaneous determination of noradrenaline, dopamine and serotonin by stepwise elution from a short column of weak cation-exchange resin

A simple method for the simultaneous determination of noradrenaline, dopamine and serotonin using a short column of Amberlite CG-50 is described. Noradrenaline and dopamine were eluted from the column with phosphate buffers containing 1.5 and 4.0% boric acid, respectively, and then serotonin was eluted with 1.0 N HCl. Catecholamines were determined by a modification of the ethylenediamine condensation method using potassium ferricyanide as oxidant and isobutanol for extraction of the fluorophores. Serotonin was measured by the acidic o-phthalaldehyde method. The method was applied to the simultaneous determination of noradrenaline, dopamine and serotonin in discrete regions of rat brain.

FREE 3‐METHOXY‐4‐HYDROXYPHENYLETHYLENEGLYCOL IN THE CENTRAL NERVOUS SYSTEM OF THE RAT: SEMI‐AUTOMATED FLUOROMETRIC ASSAY, TURNOVER AND EFFECTS OF DRUGS

AbstractA semi‐automated fluorometric assay technique for free 3‐methoxy‐4‐hydroxyphenylethyl‐eneglycol (MOPEG) in rat brain and spinal cord is described.The method is based on a simple manually‐performed two‐step purification procedure using column chromatography on Sephadex G 10 and DEAE‐Sephadex A 25 (borate form) respectively. After isolation MOPEG is converted into a fluorophore in a continuous flow system using ethylene diamine condensation in the presence of an oxidant. The MOPEG assay is highly sensitive (detection limit 2 ng/sample) and linear, with an overall recovery of approx 75%.Specificity is demonstrated by testing a number of compounds and confirmed by gas chromatography‐mass spectrometry analysis. Treatment with clozapine and haloperidol (both neuroleptics), reser‐pine (impairing intraneuronal storage) or phenoxybenzamine (α‐adrenoceptor blocking agent) increased the content of MOPEG both in brain and spinal cord. Cerebral levels of MOPEG were decreased after injection of a single dose of the tricyclic antidepressant desipramine and after chronic destruction of the locus coeruleus by electrolytic lesion or by the administration of the neurotoxic drug 6‐hydroxy‐dopamine. Animals killed by microwave irradiation did not show lower MOPEG contents in brain than decapitated animals.These results indicate that MOPEG is a measure for changes in central noradrenaline turnover and that drugs affect MOPEG in the brain and spinal cord similarly. Fractional rate constants of MOPEG in the rat brain and spinal cord were estimated with the exponential decline curves produced by treatment with pargyline. Turnover rates of 193 pmol/g/h and 167 pmol/g/h in the brain and spinal cord respectively were calculated.

Modified ethylenediamine condensation method and its application in the analysis of catecholamines by ion-exchange chromatography

A modified ethylenediamine condensation method is described in which catecholamines dissolved in a borate buffer are convertedd into fluorescent products by oxidation with hexacyanoferrate(III) in the presence of ethylenediamine under alkaline conditions. The method was applied successfully in the fluorimetric determination of catecholamines eluted from a column of weakly acidic ion-exchange resin with a mixed buffer of pH 6.3 containing 0.35 M boric acid and 0.002 M disodium ethylenediaminetetraacetate. An analysis of human urine for catecholamines is described.

A method for determination of 3,4-dihydroxyphenylacetic acid and 3,4-dihydroxymandelic acid in urine

A fluorometric method is described for the determination of urinary 3,4-dihydroxyphenylacetic acid (DOPAC) and 3,4-dihydroxymandelic acid (DOMA). This method is based upon ethyl acetate extraction, electrophoretic separation, and conversion of these compounds to highly fluorescent ethylenediamine condensation products. The normal urinary content of DOMA and DOPAC is given. The possibility of applying this method for the determination of dihydroxyphenylalanine (DOPA) is discussed.

Identification of the main ethylenediamine condensate of noradrenaline with that of catechol.

BECAUSE of the importance of fluorometric microanalysis of catecholamines, the ethylenediamine condensation method1 should be examined in detail. The specificity of this method for noradrenaline might be important. In previous communications2,3, we indicated that the main condensation product of noradrenaline or of 3,4-dihydroxymandelic acid is considered to be the same as that of catechol, and that the side-chain of noradrenaline or of 3,4-dihydroxymandelic acid might be damaged severely during the condensation reaction. Weil-Malherbe4 reported that with catechol, noradrenaline and 3,4-dihydroxymandelic acid, two main products which appear to be identical for the three compounds are formed. According to Joly and Nadeau5, at least three of the fluorescent spots on a two-dimensional paper chromatogram of an ethylenediamine condensate of tagged adrenaline (β-14C-DL-adrenaline) were not radioactive, and these three fluorescent spots were found to be common to the three chromatograms obtained from adrenaline, noradrenaline and catechol.

Increased sensitivity of ethylenediamine analysis for norepinephrine.

ATTEMPTS have been made to increase the sensitivity of analysis for catecholamines using the ethylenediamine condensation method described by Weil-Malherbe and Bone1. The objective was to be able to determine catecholamine-levels of 0.05 µgm. and below. Examination of the intensity of fluorescence of norepinephrine after various periods of heating demonstrated, in agreement with others2,3, that 1–2 hr. heating at 50° C. was optimum. It was also possible to obtain the same intensity of fluorescence by permitting the reaction to proceed at room temperature for about 7 hr. or at 5° C. overnight. At 50° C. the intensity of fluorescence was found to be maximum in 20 min. for epinephrine and in 40–50 min. for dopamine. When using the Klett fluorimeter, the fluorescence for epinephrine was stable while that for norepinephrine and dopamine was not.

Identification of the main ethylenediamine condensate of noradrenaline with that of catechol.

BECAUSE of the importance of fluorometric microanalysis of catecholamines, the ethylenediamine condensation method1 should be examined in detail. The specificity of this method for noradrenaline might be important. In previous communications2,3, we indicated that the main condensation product of noradrenaline or of 3,4-dihydroxymandelic acid is considered to be the same as that of catechol, and that the side-chain of noradrenaline or of 3,4-dihydroxymandelic acid might be damaged severely during the condensation reaction. Weil-Malherbe4 reported that with catechol, noradrenaline and 3,4-dihydroxymandelic acid, two main products which appear to be identical for the three compounds are formed. According to Joly and Nadeau5, at least three of the fluorescent spots on a two-dimensional paper chromatogram of an ethylenediamine condensate of tagged adrenaline (β-14C-DL-adrenaline) were not radioactive, and these three fluorescent spots were found to be common to the three chromatograms obtained from adrenaline, noradrenaline and catechol.

Failure of ethylenediamine condensation method to detect increased plasma norepinephrine concentrations during general anesthesia in man.

Analysis of human plasma by the ethylenediamine condensation method did not reveal a striking increase in norepinephrine concentration during general anesthesia, although this elevation could be clearly shown both by biologic assay and by the more specific trihydroxyindole method. This disercpancy probably results from the presence in normal plasma of relatively large amounts of biologieally inactive eateehol substance or substances whieh interfere with analyses made by ethylenediamine condensation.

The Determination of Catechol Amines in Blood

Abstract (1)The effect of light on the fluorescence of the ethylene diamine condensation products of the oxidized catechol amines has been studied. (2)It was found that exposure of the norepinephrine derivative for 30 minutes to light reduced the fluorescence to a very low level. The epinephrine complex, on the other hand, is only slightly affected by the same exposure. (3)On the basis of this differential sensitivity to light a sensitive method for the quantitative determination of the two catechol amines in blood has been developed. (4)The levels of epinephrine and norepinephrine in the blood of normal individuals were found to range from 0.1-1.5 µg per liter and 0.3-4.0 µg per liter, respectively. (5)Further work must be done before this method can be applied to the determination of the catechol amines in urine.