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The Maillard reaction kinetics in the confined volume of the thin film produced by ESI microdroplet deposition was studied by mass spectrometry. The almost exclusive formation of the Amadori product from the reaction of D-xylose and D-glucose toward L-glycine and L-lysine was demonstrated. The thin film Maillard reaction occurred at a mild synthetic condition under which the same process in solution was not observed. The comparison of the thin film kinetics with that of the reaction performed in solution showed strong thin film rate acceleration factors. [ABSTRACT FROM AUTHOR]

The CS2O+ ion and CS2O molecule were prepared and structurally characterized by mass spectrometric techniques as isolated species in the gas phase. The theoretical analysis, performed by B3LYP and CCSD(T) computational methods, predicted different CS2O+ isomers, SSCO+, O(CS2)+, SCSO+, SCOS+ and S(COS)+, and structurally related singlet and triplet CS2O. Experiment and theory agree in identifying the obtained CS2O+ ions as a mixture of SCSO+ and SCOS+ isomers. CS2O neutral species, prepared by neutralization-reionization mass spectrometry, were directly characterized as intact, long-lived species with a lifetime τ>=2 μs. [ABSTRACT FROM AUTHOR]

A gas‐phase investigation of the D‐fructose dehydration reaction in the presence of base has been performed by the joint application of mass spectrometric techniques and theoretical calculations. Protonated addition products of D‐fructose and base were generated in the gas phase by electrospray ionization using several bases of different proton affinity. The intermediates, products and decomposition channels were investigated by ion trap mass spectrometry. Electronic structure calculations allowed the identification of the ionic intermediates and products of a selected system containing NH3, helping to rationalize the observed reaction pathways. The obtained results show that the final product, the protonated 5‐hydroxymethyl‐2‐furaldheyde [5‐HMF]H+, is better formed using selected bases and only if these remain clustered until the end of the dehydration process. [ABSTRACT FROM AUTHOR]

The activation of C-halogen bonds by the SO .+ radical cation is investigated in the gas phase. The CCl bond of CH2Cl2 is activated by fast and effective chloride-ion transfer, whereas the CF bond of CH2F2 is activated by a very slow fluoride-ion transfer. In both cases, thermodynamic and kinetic factors account for the type of process and the observed selectivity, that is, carbon-halogen versus carbon-hydrogen activation, mainly owing to the presence of the sulfur atom. The cleavage of the CCl bond of CH2Cl2 by SO .+ is a rare example of a very effective and selective chloride-ion abstraction by a metal-free, sulfur-centred radical cation. [ABSTRACT FROM AUTHOR]

The H.-atom transfer (HAT) reaction is investigated in the gas phase, starting from two different entrance channels, O2.+/CH2X2 and CH2X2.+/O2 (X=F, Cl), that correspond to a step of hydride transfer and to HAT, respectively. Analysis of the spin and charge along the reaction pathway shows that HAT occurs through the same reacting configuration, irrespective of whether the reactants are formed within the complex or are free isolated species. [ABSTRACT FROM AUTHOR]

Abstract: The new nitrogen-rich oxide N3O has been detected in the gas phase by mass spectrometric experiments. The radical has been assigned a minimum lifetime of 0.7μs and an open-chain NNNO structure in the quartet state. Structures and energies of the N3O+ precursor ion and the N3O radical have been investigated by ab initio calculations. [Copyright &y& Elsevier]

The new radical HS4containing three sulfur−sulfur bonds has been detected in the gas phase by mass spectrometric experiments. Structures and energies of HS4in the three oxidation states +/0/− have been investigated by ab initio calculations. HS4is characterized by the HSSSS open-chain structure, and it is stable toward dissociation into S2and HS2by 23 kcal mol−1. The first detection of HS4−, the conjugate base of the strong acid H2S4is also reported. [ABSTRACT FROM AUTHOR]

Abstract: A theoretical study performed at B3LYP and CCSD(T) level of theory of the reaction of formation of S3O+ in ionized carbonyl sulphide/disulphur monoxide mixtures is reported here. The interaction of carbonyl sulphide with disulphur monoxide cation leads to three different [CS3O2]+ isomers, essentially formed by a S3O+ cation solvated by a CO molecule. The S3O+ cation is present in the three structures cis, trans and ring, showed also by the isolated S3O+ species. The complex with the ring S3O+ unit is the most stable, but a direct path to its formation starting from OCS and S2O+ has not been found in the potential energy surface of [CS3O2]+. This species can be obtained from the isomerization of the complexes containing the cis or trans S3O+ unit, overcoming relatively low barrier heights. [Copyright &y& Elsevier]

A hitherto unknown, isotope-exchange reaction is studied in ionized gaseous mixtures containing disulfur monoxide and water. The kinetics, mechanism, and intermediate of the reaction are investigated by experimental and theoretical methods. The reactivity of the S2O˙+ cation with water is investigated under a wide range of pressures ranging from 10−7 to 10−4 Torr, by FT-ICR, TQ, and high-resolution CAD mass spectrometry. In the high-pressure limit the reaction proves to be a route to strongly bound sulfur-containing species. [Copyright &y& Elsevier]

Abstract: The oxywater cation H2OO+ was generated in the gas phase by ionization of mixtures containing O3, O2 and H2O. Different ionic mixtures, rich in either the H2OO+ or the HOOH+ isomer, were obtained by O3/O2/H2O–O2/H2O CI, and by CH3OH/O2–CH2O/O2 CI, respectively. The H2O2 + ions were characterized by high-resolution CAD mass spectrometry, and structural and energetic effects were examined. [Copyright &y& Elsevier]

Abstract: An ionic route to the CS2 degradation was studied by mass spectrometric and theoretical methods. Ionized mixtures containing carbon disulfide and ozone prove an effective source of ions, formed by remarkable molecular reorganization and open to further reactions with ozone and surrounding species. Both the O-transfer and dissociative oxidation processes, typical of the O3 reactivity in ionized mixtures, were observed. [Copyright &y& Elsevier]

Graphical abstract Highlights • Chromium oxide anions are effective oxidizing and reducing agents in the gas phase. • The reactions are allowed by the formation of stable ion-dipole complexes. • The basic site of the anion coordinates either the sulfur or oxygen atom of SO 2. • The oxidation is an effective route to the formation of SO 3. • Sulfur dioxide plays a special role in addressing the reactivity from oxidation to reduction. Abstract Unprecedented redox reactions of chromium oxide anions have been observed in the gas phase and investigated by mass spectrometric techniques and electronic structure calculations. The effective oxidizing and reducing power of chromium oxide anions is unravelled by sulfur dioxide: CrO 4 − and CrO 2 − generate CrO 3 − as the reduction and oxidation product, respectively, together with SO 3 and SO as the oxidation and reduction products of SO 2 , respectively. Computations predict that the reactions of CrO 4 − and CrO 2 − proceed through rather stable ion-dipole complexes and that CrO 4 - produces also a strongly bound [CrSO 6 ] - species. [ABSTRACT FROM AUTHOR]

The gas-phase reactivity of doubly-charged vanadium hydroxides anions with SO2 has been studied by experimental and computational methods. The obtained results highlight the role of sulfur dioxide in promoting unprecedented bond-forming reactions, which produce singly-charged products by breaking the V xO y skeleton or a terminal V−O bond. [ABSTRACT FROM AUTHOR]

The reactivity of [NaL·ClO2]− cluster anions (L = ClOx−; x = 0–3) with sulphur dioxide has been investigated in the gas phase by ion–molecule reaction experiments (IMR) performed in an in-house modified Ion Trap mass spectrometer (IT-MS). The kinetic analysis revealed that SO2 is efficiently oxidised by oxygen-atom (OAT), oxygen-ion (OIT) and double oxygen transfer (DOT) reactions. The main difference from the previously investigated free reactive ClO2− is the occurrence of intracluster OIT and DOT processes, which are mediated by the different ligands of the chlorite anion. This gas-phase study highlights the importance of studying the intrinsic properties of simple reacting species, with the aim of elucidating the elementary steps of complex processes occurring in solution, such as the oxidation of sulphur dioxide. [ABSTRACT FROM AUTHOR]

[Display omitted] • Transition metal dioxide anions effectively react with SO 2 in the gas phase. • CuO 2 − and ZnO 2 − oxidate SO 2 to SO 4 − by double oxygen transfer. • CoO 2 − and NiO 2 − consecutively ligate two SO 2 molecules. • Ligation of H 2 O to ZnO 2 − changes the reactivity to single oxygen transfer to form SO 3 −. • Spin density on the metal plays a special role in addressing the reactivity. The reactivity of transition metal dioxide anions of cobalt, nickel, copper and zinc with sulfur dioxide has been investigated in the gas phase by mass spectrometric techniques and theoretical calculations. Dioxide anions of the late transition metals Cu and Zn promote an unprecedented fast and efficient oxidation to the sulfate radical anion through a double oxygen transfer, whereas the earlier transition metals Ni and Co only undergo the addition of two SO 2 molecules. The ligation of a water molecule to ZnO 2 − switches the reaction path to a single oxygen anion transfer, forming SO 3 −. [ABSTRACT FROM AUTHOR]

Doubly ‐ charged vanadium cluster anions undergo fast and efficient bond ‐ forming reactions, producing singly ‐ charged products. The charge separation process does not occur by exothermic electron transfer or fragmentation, but by reaction with sulfur dioxide, which promotes the breakage of strong V−O bonds and formation of new V−O and S−O bonds. More information can be found in the Communication by A. Troiani, G. de Petris et al. on page 11752. [ABSTRACT FROM AUTHOR]