Tautomeric Equilibria Studies by Mass Spectrometry

Tautomerism in organic chemistry has been extensively studied in condensed phase by spectrometric methods, mainly by IR and NMR techniques. Mass spectrometry studies start 40 years ago but just recently it has been recognized the importance of the mass spectral data for the study of tautomerism in the gas phase.
Mass spectrometry can provide valuable information in regard to tautomeric equilibria when studying mass spectra among the members of different families of organic compounds.
The relevance of the mass spectral data resides on several facts but there are two that are of key importance:
1-	Mass spectral fragmentation assignments should be tautomer specific since the corresponding abundances ratios are supposed to be correlated to the keto/enol contents.
2-	Ionization in the ion source is supposed to have no effect on the position of the equilibrium so that the results reflect the tautomers content in the gas phase previous to ionization.
Some of the carbonylic compounds do not exhibit noticeable tautomerism so the fragment abundances assigned to the enol form is very low or not measurable. Since enolization is more noticeable in the case of thio-derivatives (which correlates adequately with the oxygenated analogues), the study of their mass spectra is an interesting choice to reach some degree of generalization. 
In addition, experimental findings are supported by semiempirical theoretical calculations, which probed to be adequate not only for supporting tendency correlations among the members of a compound family but also to calculate heats of tautomerization in gas phase.
Reports using mass spectrometry for tautomerism are becoming less common. One of the reasons is that now it would appear that the interpretation of MS results is not as straightforward as it was once believed, even though in a recent review it was written that: “Mass spectrometry is the most informative and practical method for studying and identifying tautomers in the gas phase” [1]. 
In fact, mass spectrometry seems to be very informative for studying and identifying tautomers, because in this case external factors like solvents, intermolecular interactions, etc., can be excluded by transferring the tautomeric system into gas phase, where the process becomes truly unimolecular [1].
This review covers the study of Tautomerism by Mass Spectrometry in the last four decades. 
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Interprofessional Working in Practice – Avoiding a Theory-Practice Gap

This paper aims to encourage and promote further discussion around the theme of the theory and practice gap in the teaching and practice of interprofessional education (IPE) in pre-registration health and social care. Following a brief history of IPE, we consider the importance of providing students with supported opportunities to observe, learn and put into practice IPE. We also highlight the necessity of involving practitioners in creating health professionals who are ‘fit for purpose’ at qualification

Solar heating and cooling of housing : |b five institutional analysis case studies

This paper is one of a series resulting from institutional analysis of photovoltaic (PV) acceptance. The case studies reported here involve use of solar thermal technologies in various residential settings. All of the projects are part of the DOE-HUD Solar Heating and Cooling Demonstration Program. This program provides grants to developers to prompt them to use this innovation. Each of the five cases illustrates one or more institu- tional forces which influence the acceptance of solar energy in the resi- dential sector. Friends Community is an instance of developer involvement for reasons other than profit, and the way in which other factors (such as designers and consumers) react to such housing development. Reservoir Hills Solar Houses illustrates the process of entry by new development firms, the role of public agencies in encouraging various forms of housing and the problems of using product innovations without adequately developed industry support infrastructures. Project Solar for Indiana illustrates the import- ance of supporting institutional networks, in this case the homebuilders association, the state government and key individuals, who play mediating and legitimating roles in solar acceptance. Solar in California discusses public efforts at a city level -- Santa Clara, a county level -- San Diego, and the state level in what is generally regarded as the state most active in turning to forms of solar energy. Finally, PNM/AMREP illustrates the process of large development corporation decision making, and the manner in which an investor- owned utility is shifting its orientation of energy provision

Substituent, Temperature and Solvent Effects on the Keto-Enol Equilibrium in β-Ketoamides: A Nuclear Magnetic Resonance Study

Substituent, temperature and solvent effects on tautomeric equilibria in several β-ketoamides have been investigated by means of nuclear magnetic resonance spectroscopy (NMR). Keto-enol equilibrium predominates over the amide-imidol one. The relative stability of the individual tautomers and the corresponding equilibrium shifts are explained consider- ing electronic and steric effects and tautomer stabilization via internal hydrogen bonds. In solution, these compounds exist mainly as ketoamide and Z-enolamide tautomers, both presenting intramolecular hydrogen bonds.Facultad de Ciencias ExactasLaboratorio de Estudio de Compuestos Orgánicos (LADECOR

Mechanism of Aromatic Hydrocarbon Acylation by Substituted Benzoic Acids: A Novel Reaction Pathway

Aromatic hydrocarbons are susceptible to direct acylation by benzoic acids with high yields bearing ortho or para alkyl groups as substituents under Friedel–Crafts reaction conditions. The α-H of the alkyl moiety seems to be responsible for the observed relatively high reaction rates of conversion. Carbanion-like species are proposed as reaction intermediates, which also operate as strong bases in the reaction rate-determining steps. Trapping experiments, deuterium isotopic effects, and kinetics data favor a concerted reaction pathway where proton transfer from the hydrocarbon molecule to a carbanionic intermediate takes place with a simultaneous electrophilic attack of the carbonylic carbon atom.Facultad de Ciencias ExactasLaboratorio de Estudio de Compuestos Orgánico

Spectrometric Studies and Semi-Empirical Calculations of Some Thiomorpholides

Mass spectra of selected thiomorpholides have been analysed and specific fragmentation assignments have been done to characterised and weigh co-existing keto and enol tautomers. The predictive value of this methodology in regard to keto-enol equilibria occurring in gas phase is not only supported by the influence of substitution nature and size of these but also by the good correlation found between the selected fragments abundances ratio, semi-empirical calcula- tion (AM1) of the corresponding heats of tautomerization and nuclear magnetic resonance data. The results show that the thioketo-thioenol equilibrium can be studied by mass spectrometry where ionization in the ion source has a negligible ef- fect on the position of that equilibrium and by GC/MS where solvent separation in the analytical column seems to pre- clude shifts from the equilibrium reached at the injection port of the gas chromatograph.Laboratorio de Estudio de Compuestos OrgánicosInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Substituent, Temperature and Solvent Effects on the Keto-Enol Equilibrium in β-Ketoamides: A Nuclear Magnetic Resonance Study

Substituent, temperature and solvent effects on tautomeric equilibria in several β-ketoamides have been investigated by means of nuclear magnetic resonance spectroscopy (NMR). Keto-enol equilibrium predominates over the amide-imidol one. The relative stability of the individual tautomers and the corresponding equilibrium shifts are explained consider- ing electronic and steric effects and tautomer stabilization via internal hydrogen bonds. In solution, these compounds exist mainly as ketoamide and Z-enolamide tautomers, both presenting intramolecular hydrogen bonds.Facultad de Ciencias ExactasLaboratorio de Estudio de Compuestos Orgánicos (LADECOR

Substituent, Temperature and Solvent Effects on the Keto-Enol Equilibrium in β-Ketoamides: A Nuclear Magnetic Resonance Study

Substituent, temperature and solvent effects on tautomeric equilibria in several β-ketoamides have been investigated by means of nuclear magnetic resonance spectroscopy (NMR). Keto-enol equilibrium predominates over the amide-imidol one. The relative stability of the individual tautomers and the corresponding equilibrium shifts are explained consider- ing electronic and steric effects and tautomer stabilization via internal hydrogen bonds. In solution, these compounds exist mainly as ketoamide and Z-enolamide tautomers, both presenting intramolecular hydrogen bonds.Facultad de Ciencias ExactasLaboratorio de Estudio de Compuestos Orgánicos (LADECOR