Giancarlo Verardo

Rapid mixed mode solid phase extraction method for the determination of acrylamide in roasted coffee by HPLC-MS/MS.

In this work, a rapid and reliable purification method based on a single mixed solid phase extraction (SPE) column, for the determination of acrylamide in roasted coffee by liquid chromatography-tandem mass spectrometry, was developed. Deuterium labelled d(3)-acrylamide was used as internal standard. Acrylamide was extracted by 10 mL of water and the extract purified by a single SPE column consisting of 0.5 g of an in-house prepared mixture of C18, strong cation (SCX) and anion exchange (SAX) sorbents in the ratio 2/1.5/1.5 (w/w/w). The amount of the three sorbents was optimised in order to eliminate the main interfering compounds present in coffee extracts, such as melanoidins, trigonelline, chlorogenic acids and caffeine. The SPE procedure was very simple and consisted of pushing 1 mL of an aqueous coffee extract through the SPE column followed by 1 mL of water which was collected for the analysis. The method was tested on six samples of roasted coffee of different composition and roasting level. The repeatability of the method, expressed as relative standard deviation (n=6), was lower than 5%. The recovery of acrylamide at three spiked levels ranged from 92% to 95%. The limits of detection (LOD) and quantitation (LOQ) were 5 and 16 μg kg(-1), respectively.

Analysis of underivatized oligosaccharides by liquid chromatography/electrospray ionization tandem mass spectrometry with post-column addition of formic acid

Underivatized oligosaccharides were analyzed by electrospray ionization (ESI) using a linear ion trap mass spectrometer in the negative ion mode with post-column addition of an aqueous solution of formic acid. Under these conditions all oligosaccharides showed the presence of the corresponding formate adduct [M + HCOO](-) with high intensity and easy subsequent low-energy collision-induced dissociation (CID) fragmentation using successive MS(n) experiments. A careful examination of the mass spectra obtained from these MS(n) experiments pointed out some significant differences useful to identify and quantify the single components in mixtures of coeluted disaccharides. This new sensitive and rapid method was successfully applied to the quantification of oligosaccharides in some juices minimizing sample handling.

Functionalised cis-Alkenes from the Stereoselective Decomposition of Diazo Compounds, Catalysed by [RuCl(η5-C5H5)(PPh3)2]

A catalytic amount of [RuCl(η5-C5H5)(PPh3)2] (1) (0.1 mol-%) at 60 °C stereoselectively decomposes α-diazo carbonyl compounds N2CHCOR [R = EtO, Me, Et, nPr, iPr, Ph, (CH2)10Me, and (CH2)14Me] affording quantitatively RCOCH=CHCOR carbene dimers [R = EtO (10), Me (11), Et (12), nPr (13), iPr (14), Ph (15), (CH2)10Me (16), and (CH2)14Me (17)]. The cis isomer is formed in 95−99% purity, depending on the R group. Under the same experimental conditions, N2CHCOR1 and N2CHCOR2 react in equimolar amounts to give mixtures of unsymmetrical cis-R1COCH=CHCOR2 (18−32), and symmetrical cis-R1COCH=CHCOR1 and cis-R2COCH=CHCOR2 alkenes. The unsymmetrical cis-alkenes 23−32 are formed in about 50% yield from the reaction between two α-diazo ketones. The yield of the cis-R1COCH=CHCOR2 compounds 18−22 increases to ca. 60% when a mixture of α-diazo ketone and N2CHCOOEt is catalytically decomposed. Higher conversions into the unsymmetrical products have been obtained by treating N2CHCOR and N2CHSiMe3, from which cis-RCOCH=CHSiMe3 derivatives 34−41 are formed in 83−91% yield. The catalytic decomposition of α,ω-bis(diazo) ketones N2CHCO(CH2)nCOCHN2 (n = 4, 8, or 10) has also been investigated, and found to afford cyclic cis-alkenes arising from both intra- [n = 4 (45), 8 (46), and 10 (47)] and intermolecular carbene-carbene coupling processes.

The reaction between acyl halides and alcohols: Alkyl halide vs. Ester formation

Abstract In the reaction between an acyl halide and an alcohol the thermodynamically favoured prodtcts are the free carboxylic acid and the alkyl halide. The initial reaction is, generally, the formation of an dster and HHal. Vhen the alcohol is very prone tn yield an alkyl cation upon protonation by HHal, formed H 2 O exhibited a supdrior reactivity and competed successfully with the alcohol for the acyl halide making, therefore, ester formation practically confined to a triggering role. But, in those cases where the cation is less easily formed, ester formation was favoured and, consequently, became the necessary elementary step towards alkyl halide formation. This final product, on the other hand, might be extremely slow to form in an S N 2 reaction between the protonated ester function and the halide ion. In these hnstances, therefore, as well as in the cases when a basic solvent competes for the proton of HHal, the ester is the final product. A notable exception of the shtuation above ottlined, is given by α-hydroxy,α-phenylbenzeneacetic acid (2y), which appears to undergo direct chlorine-hydroxyl interchange through a quaternary intermediate (E), in the end collapsing to α-chloro-α-phenyl-benzeneacetic acid (4y). Different systems were compared using CH 2 Cl 2 as a solvent under strictly similar conditions. Some 28 different substrates were tested for reaction with AcCl (1a), whereas the action of eight acyl halides (1) against ( RS )-α-methylbenzenemethanol (2n) and α-phenylbenzenemethanol (2p), as well as the effect of five different solvents on the reaction between two alcohols (2p and 2-methyl-2-propanol, 2c) with 1a, were observed.

Effect of vacuum roasting on acrylamide formation and reduction in coffee beans

Coffea arabica beans were roasted in an oven at 200 °C for increasing lengths of time under vacuum (i.e. 0.15 kPa). The samples were then analysed for colour, weight loss, acrylamide concentration and sensory properties. Data were compared with those obtained from coffee roasted at atmospheric pressure (i.e. conventional roasting), as well as at atmospheric pressure for 10 min followed by vacuum treatment (0.15 kPa; i.e. conventional-vacuum roasting). To compare the different treatments, weight loss, colour and acrylamide changes were expressed as a function of the thermal effect received by the coffee beans during the different roasting processes. Vacuum-processed coffee with medium roast degree had approximately 50% less acrylamide than its conventionally roasted counterpart. It was inferred that the low pressure generated inside the oven during the vacuum process exerted a stripping effect preventing acrylamide from being accumulated. Vacuum-processed coffee showed similar colour and sensory properties to conventionally roasted coffee.

Ketimines From Ketones and Ammonia

Abstract The direct synthesis of ketimines from ammonia and ketones catalyzed by ammonium chloride is described.

Aromatic tertiary amines and n-butyl nitrite

Abstract The reaction between alkyl nitrites, particularly n-butyl nitrite, and tertiary aromatic amines under a variety of experimental conditions promptly yielded products of N-dealkylation-N-nitrosation, ring nitration, ipso-substitution and, occasionally, combinations of these processes. Aminoethers were detected as final products and intermediates on the way to N-nitrosations. Reaction pathways are suggested for some of the observed behaviours on the basis of experimental evidences whereas other alternatives are discarded.

Generation and Rearrangements of Ylides from Tertiary Amines and α-Diazo Ketones − Very High Catalytic Activity of [RuCl(η5-C5H5)(PPh3)2]

The reaction of N,N-dimethyl-2-propen-1-amine, N,N-dimethylbenzylamine and N,N-dimethyl-2-propyn-1-amine with the α-diazo ketones N2CHCOR [R = Me (2a), Et (2b), nPr (2c), iPr (2d), (CH2)10Me (2e), (CH2)14Me (2f) or Ph (2g)] in a 1:1 molar ratio, catalysed by the complex [RuCl(η5-C5H5)(PPh3)2] (1) (1% mol), have been investigated. Noticeably, the corresponding α-amino ketones 3a−g, 4a−g and 5a−g are readily and quantitatively formed by rearrangement of transient nitrogen ylides. Compounds 3−5, most of which have not yet been reported, have been isolated and fully characterised by IR, 1H and 13C NMR spectroscopy and GC-MS. It has been proved that complex 1 is an excellent and specific catalyst for the generation of nitrogen ylides from diazo carbonyls.

N-Dealkylation-N-nitrosation of tertiary aromatic amines by N-butyl nitrite

Abstract N,N-Dialkyl aromatic amines with a variety of ring substituents are N-dealkylated and N-nitrosated efficiently by n-butyl nitrite/ammonium chloride/water at reflux temperature. Ring nitrosation was never observed, but minor amounts of m- and p-nitro amines and/or nitrosamines were formed in some cases. Ring nitration is rather a reaction of the initial substrate than a process occurring on formed nitrosamines. The leaving propensities of the initial N-substituents to yield nitrosamines were in the order benzyl methyl alkyl.

New Heterocycles from the Reaction between Some Natural α-Amino Acid Hydrazides and Formaldehyde

The ring forming condensation between some natural α-amino acid phenylhydrazides (1) and aqueous formaldehyde (2) has opened a novel synthetic route to hexahydro-1,2,4-triazin-6-one derivatives (3). Polycyclic systems were obtained from the same reaction carried out with L-aspartic acid 1,4-bis(2-phenylhydrazide) (1d), L-histidine phenylhydrazide (1e) and L-tryptophan phenylhydrazide (1f) which gave perhydro-4,6-dioxo-2,8-diphenyl[1,2,4]triazino[4,5-d][1,2,4]triazepine (5) perhydro-1-oxo-3-phenylimidazo[5,4-d][1,2,4]triazino[4,5-a]pyridine (7) and 1,2,3-H-3-(2-phenylcarbazoyl)-β-carboline (8), respectively. Substrates 1 were conveniently obtained by direct reaction of phenylhydrazine with L-α-amino acid esters retaining the original chirality.