Synthesis of isotope-labelled methoxypyrazine compounds as internal standards and quantitative determination of aroma methoxypyrazines in water and wines by solid-phase extraction with isotope dilution-GC-MS /

An efficient way of synthesizing the deuterium labelled analogues of three methoxypyrazine compounds: 2-d3-methoxy-3-isopropylpyrazine, 2-d3-methoxy-3- isobutylpyrazine, and 2-d3-methoxy-3-secbutylpyrazine, has been developed. To confirm that the deuterium labels had been incorporated into the expected positions in the molecules synthesized, the relevant characterization by NMR, HRMS and GC/MS analysis was conducted. Another part of this work involved quantitative determination of methoxypyrazines in water and wines. Solid-phase extraction (SPE) proved to be a suitable means for the sample separation and concentration prior to GC/MS analysis.Such factors as the presence of ethanol, salt, and acid have been investigated which can influence the recovery by SPE for the pyrazines from the water matrix. Significantly, in this work comparatively simple fractional distillation was attempted to replace the conventional steam distillation for pre-concentrating a sample with a relatively large volume prior to SPE. Finally, a real wine sample spiked with the relevant isotope-labelled methoxypyrazines was quantitatively analyzed, revealing that the wine with 10 beetles per litre contained 138 ppt of 2-methoxy-3-isopropylpyrazine. Interestingly, we have also found that 2-methoxy-3-secbutylpyrazine exhibits an extremely low detection limit in GC/MS analysis compared with the detection limit of the other two methoxypyrazines: 2- methoxy-3-isopropylpyrazine and 2-methoxy-3-isobutylpyrazine.

A fast atom bombardment mass spectrometry study of tris (3, 6-dioxaheptyl) amine-alkali metal halide complexes and hydrogen bonded complexes

The objective of this thesis was to demonstrate the potential of fast atom bombardment mass spectrometry (FABMS) as a probe of condensed phase systems and its possible uses for the study of hydrogen bonding. FABMS was used to study three different systems. The first study was aimed at investigating the selectivity of the ligand tris(3,6-dioxaheptyl) amine (tdoha) for the alkali metal cations. FABMS results correlated well with infrared and nmr data. Systems where a crown ether competed with tdoha for a given alkali metal cation were also investigated by fast atom bombardment. The results were found to correlate with the cation affinity of tdoha and the ability of the crown ether to bind the cation. In the second and third studies, H-bonded systems were investigated. The imidazole-electron donor complexes were investigated and FABMS results showed the expected H-bond strength of the respective complexes. The effects of concentration, liquid matrix, water content, deuterium exchange, and pre-ionization of the complex were also investigated. In the third system investigated, the abundance of the diphenyl sulfone-ammonium salt complexes (presumably H-bonded) in the FABMS spectrum were found to correlate with qualitative considerations such as steric hindrance and strength of ion pairs.

An investigation into some mechanistic aspects of estrogen biosynthesis

The mechanistic aspects of the 19-hydroxy1ation and aromatization of androgens were investigated. Fungal, bacterial and mammalian enzymatic activities were studied in this regard . The fungus Pell i cular~ fi1amentosa metabolized androst-4-ene-3 , 17-dione to the corresponding 110<' , 11 f and 14 0( hydroxylated derivatives. No ~19- hydroxylated products were isolated, although this transformation was previously observed for the C21-steroids . The intestinal bacterium Clostridi um paraputrific~ had been reported to aromatize androsten-4-ene-3,17-dione. In the present study, however, only the ring A reduced products , 17(3 - hydroxy-5f -andro8tane- 3-one and 5f-androstane-3,17-dione , were recovered . Human placental microsomes contain substantial aromatase activity and were employed in an effort to elucidate some of the mechanistic details of aromatization. Selectively deuterated steroidal substrates were employed as a probe in order to distinguish b'!tween certain of the mechanisms proposed for aromatization . Retention of deuterium at C4 and C6 was observed. It was concluded that no free intermediates allowing for loss of hydrogen from either of these two positions are implicated in this process . The involvement of a Schiff base enzyme-sup strate complex in aromatization was examined using the substrate 17f - hydroxyandrost-4-ene-3-one- 3_ 1BO. Since no loss of label was ob~erved, the implication of a Schiff base was discounted . Mixed label1ir~ studies were performed in order to determine if hydroxylation at C19 is a rate-determining process in aromatization . Isotope effects of 2 .1 and 1.7 were determined for the conversion of 17f - hydroxyandrost-4-ene-J-one-19,19,19-dJ and -19-dl respectively to estrogens. It was concluded from this that 19-hydroxylation is at l east a partially rate-determinjng process in aromatization. A homoenb~ation mechanism for 19-hydroxylation was not supported by the data obtained in this s tudy. In vitro 1JC NMR monitoring using l7f-hydroxyandrost-4-ene-Jone- 19-l3C was found not to be a successful approach in the study of steroid transformations, owing in part t o their low solubility in the incubation medium.

The 21-dehydroxylation of corticosteroids: evidence for an enol intermediate and the hydroxylation of steroids by fungal cyto-chrome P450: evidence for a stepwise mechanism

Two enzyme mechanisms were examined: the 21-dehydroxylation of corticosteroids by the anaerobe Eubacterium l en tum, and the hydroxylation of steroids by fungal cytochrome P450. Deuterium labelling techniques were used to study the enzymic dehydroxylation. Corticosteroids doubly labelled (2H) at the C-21 position were incubated with a culture of Eubacterium lentum. It was found that t he enzymic dehydroxylation proceeded with the loss of one 2H f rom C-21 per molecule of substrate. The kinetic isotope ef fect f or the reaction was found to be k~kD = 2. 28. These results suggest that enzyme/substr ate binding in this case may proceed via t he enol form of the substrate. Also , it appears that this binding is, at least in part, the rate determining step of t he reaction. The hydroxylation of steroids by fungal cytochrome P450 was examined by means of a product study. Steroids with a double bond at the A8 (9), ~( lO ), or ~ (ll) position were synthesized. These steroids were then incubated with fungal strains known to use a cytochrome P450 monooxygenase to hydroxylate at positions allylic to these doubl e bonds. The products formed in these incubations indicated that the double bonds had migrated during allylic hydroxylat ion. This suggests that a carbon centred radical or ion may be an intermediate i n the cytochrome P450 cat alytic cycle.

The satellite band patterns in the near ultraviolet absorption spectra of isotopic compounds of acetaldehyde

The 3700 A - 3000 A absorption spectra of CH3CHO and its isotopic compounds such as CH3CDO, CD3CHO and CD3CDO were studied in the gas phase at room temperature and low temperatures. The low resolution spectra of the compounds were recorded by a 1.5 m Baush and Lomb grating spectrograph. The high resolution spectra were recorded by a Ebert spectrograph with the Echelle grating and the holographic grating separately. The multiple reflection cells were used to achieve the long path length. The pressure-path length used for the absorption spectrum of CH 3CHO was up to 100 mm Hg )( 91 . 43mo The emission spectrum and the excitation spectrum of CH3CHO were also recorded in this research. The calculated satellite band patterns \vhich were ob-tailied by the method of Lewis were used to compare with the observed near UV absorption spectrum of acetaldehyde. These calculated satellite band patterns belonged to two cases: namely, the barriers-in-phase case and the barriers- out-of-phase case. Each of the calculated patterns corresponded to a stable conformation of acetaldehyde in the excited state . The comparisons showed that the patterns in the observed absorption spectra corresponded to the H-H eclipsed conformations of acetaldehyde in the excited state . The least squares fitting analysis showed that the barrier heights in the excited state were higher than in the ground state. Finally, the isotopic shifts for the isotopic compounds of acetaldehyde were compared to the compounds with the similar deuterium substitution.

Biotransformation of aromatic hydrocarbons and organic sulphides by fungi

Toluene is converted to benzyl alcohol by the fungi Mortierella isabellina and Helminthosporium species; in the latter case, the product is further metabolized. Toluene-a -d 1 , toluene-a,a-d2, and toluene-a,a,a-d 3 have been used with Mortierellaisabellina in a series of experiments to determine both primary and secondary deuterium kinetic isotope effects for the enzymic benzylic hydroxylation reaction. The values obtained, intermolecular primary kH/kD = intramolecular p rim a r y kH r kD = 1. 0 2 + O. 0 5, and sec 0 n dar y k H I kD = 1. 37 .:!. 0.05, suggest a mechanism for the reaction involving benzylic proton removal from a radical intermediate in a non-symmetrical transition state. 2H NMR (30.7 MHz) studies using ethylbenzene-l,1-d 2 , 3 -fluoroethylbenzene-l,1-d 2 , 4 -fluoroethylbenzene-l,1-d 2 , and toluene-dB as substrates with Mortierella isabellina suggest, based on the observable differences in rates of conversion between the substrates, that the hydroxylation of hydrocarbons at the benzylic position proceeds via a one electron abstraction from the aromatic ring, giving a radical cation. A series of 1,3-oxathiolanes (eight) were incubated with Mortierella isabellina , Helminthosporium , Rhizopus arrhizus , and Aspergillus niger . Sulphoxides were obtained from Mortierella isabellina and Rhizopus arrhizus using the substrates 2-phenyl-, 2-methyl-2-phenyl-, and 2-phenyl-2-tert. butyl-l,3-oxathiolane. The relative stereochemistry of 2-methyl-2-phenyl-l,3-oxathiolan-l-oxide was assigned based on lH decoupling, n.O.e, 1 and H NMR experiments. The lH NMR (200 MHz) of the methylene protons of 2-methyl-2-phenyl-l,3-oxathiolan-l-oxide was used as a diagnostic standard in assigning the relative stereochemistry of 2-phenyl-l,3-oxathiolan-l-oxide and 2-phenyl-2-tert. butyl-l,3-oxathiolan-l-oxide. The sulphoxides obtained were consistent with an oxidation occurring from the opposite side of the molecule to the phenyl substituent.

Reactions of steroidal epoxides with strong organic bases and an investigation into the syntheses of some labelled pregnane derivatives

Reactions of 5,6- and 4,5-epoxycholestane derivatives with strong bases were investigated. Epoxidation of 3a-acetoxycholest-5-ene also gave a new compound along with the anticipated epoxides. Interconversions of the latter were observed. Some possible mechanisms of its formation and rearrangements have been pIioposed. No reaction was observed with any of the 5,6- and 4,5-steroidal epoxides employed in the present study, using potassium tertiary butoxide under refluxing conditions. n-Butyllithium reacted only with 5,6-epoxycholestanes bearing a ketal moiety at the C3 carbon. Opening of the ketal group was observed with n-butyllithium in the case of a ~-epoxide. The reaction was also investigated in the absence of epoxide functionality. A possible mechanism for the opening of ketal group has been proposed. Lithium diethylamide (LDEA) was found effective in rearranging 5,6- and 4,5-epoxides to their ~orresponding allylic alcohols. These rearrangements presumably proceed via syn-eliminations, however the possibility of a corresponding anti-elimination has not been eliminated. A substituent effect of various functional groups (R = H, OH, OCH2CH20) at C3 has-been observed on product distribution in the LDEApromoted rearrangements of the corresponding epoxides. No reaction of these epoxides was observed with lithium diisopropylamide (LDA) • In the second part of the project, several attempts were made towards the sYRthesis of deoxycorticoste~one~17,2l,2l~d3' a compound desirable for the 2l-dehydroxylation studies of deoxycorticosterone. Several routes were investigated, and some deuterium labelled pregnane derivatives were prepared in this regard. Microbial 21-hydroxylation of progesteronel7,21,21,2l- d4 by ~ niger led to loss of deuterium from C21 of the product. An effort was made to hydroxylate progesterone microbially under neutral condtions.

The 21-dehydroxglation of corticosteroids of Eubacterium lentum and the dehalogenation of 4-chlorobenzoic acid by 4-chlorobenzoate dehalogenase

Two enzyme mechanisms were investigated: the 21-dehydroxylation of corticosteroids by Eubacterium lentum and the dehalogenation of 4-chlorobenzoic acid by Pseudomonas sp. CBS 3. , Chemical and enzymic methods of reduction of 21-oxo steroids were used to generate C-21-d1 compounds of tetrahydrodeoxycorticosterone, with both predominant stereochemistries. It was found that during the dehydroxylation the pro-S hydrogen at the C-21 position was lost preferentially. This suggests that the enzyme removes the pro-S hydrogen during binding to the active site as the ene-diol. To study the hydrolytic replacement of chlorine by hydroxyl , p-chlorobenzoic acid-d4 was prepared and sent to Germany for an ~ncubation with an enzyme preparation of 4-Chlorobenzo~te Dehalogenase. Results suggests the possible loss of deuterium during the conversion of p-chlorobenzoate to p-hydroxybenzoate, from all four ring positions. Many methods of preparing the control compound p-hydroxybenzoic acid-d4 were investigated.

Developing a numerical inverse-theory-based extraction of orientation-dependent relaxation rates from partially- relaxed spectra

Second-rank tensor interactions, such as quadrupolar interactions between the spin- 1 deuterium nuclei and the electric field gradients created by chemical bonds, are affected by rapid random molecular motions that modulate the orientation of the molecule with respect to the external magnetic field. In biological and model membrane systems, where a distribution of dynamically averaged anisotropies (quadrupolar splittings, chemical shift anisotropies, etc.) is present and where, in addition, various parts of the sample may undergo a partial magnetic alignment, the numerical analysis of the resulting Nuclear Magnetic Resonance (NMR) spectra is a mathematically ill-posed problem. However, numerical methods (de-Pakeing, Tikhonov regularization) exist that allow for a simultaneous determination of both the anisotropy and orientational distributions. An additional complication arises when relaxation is taken into account. This work presents a method of obtaining the orientation dependence of the relaxation rates that can be used for the analysis of the molecular motions on a broad range of time scales. An arbitrary set of exponential decay rates is described by a three-term truncated Legendre polynomial expansion in the orientation dependence, as appropriate for a second-rank tensor interaction, and a linear approximation to the individual decay rates is made. Thus a severe numerical instability caused by the presence of noise in the experimental data is avoided. At the same time, enough flexibility in the inversion algorithm is retained to achieve a meaningful mapping from raw experimental data to a set of intermediate, model-free

Elucidation of a mechanism of cell lysis by chorhexidine : a biophysical approach

Chlorhexidine is an effective antiseptic used widely in disinfecting products (hand soap), oral products (mouthwash), and is known to have potential applications in the textile industry. Chlorhexidine has been studied extensively through a biological and biochemical lens, showing evidence that it attacks the semipermeable membrane in bacterial cells. Although extremely lethal to bacterial cells, the present understanding of the exact mode of action of chlorhexidine is incomplete. A biophysical approach has been taken to investigate the potential location of chlorhexidine in the lipid bilayer. Deuterium nuclear magnetic resonance was used to characterize the molecular arrangement of mixed phospholipid/drug formulations. Powder spectra were analyzed using the de-Pake-ing technique, a method capable of extracting both the orientation distribution and the anisotropy distribution functions simultaneously. The results from samples of protonated phospholipids mixed with deuterium-labelled chlorhexidine are compared to those from samples of deuterated phospholipids and protonated chlorhexidine to determine its location in the lipid bilayer. A series of neutron scattering experiments were also conducted to study the biophysical interaction of chlorhexidine with a model phospholipid membrane of DMPC, a common saturated lipid found in bacterial cell membranes. The results found the hexamethylene linker to be located at the depth of the glycerol/phosphate region of the lipid bilayer. As drug concentration was increased in samples, a dramatic decrease in bilayer thickness was observed. Differential scanning calorimetry experiments have revealed a depression of the DMPC bilayer gel-to-lamellar phase transition temperature with an increasing drug concentration. The enthalpy of the transition remained the same for all drug concentrations, indicating a strictly drug/headgroup interaction, thus supporting the proposed location of chlorhexidine. In combination, these results lead to the hypothesis that the drug is folded approximately in half on its hexamethylene linker, with the hydrophobic linker at the depth of the glycerol/phosphate region of the lipid bilayer and the hydrophilic chlorophenyl groups located at the lipid headgroup. This arrangement seems to suggest that the drug molecule acts as a wedge to disrupt the bilayer. In vivo, this should make the cell membrane leaky, which is in agreement with a wide range of bacteriological observations.

Hydrosilylation and hydroboration catalyzed by imido-hydride complexes of molybdenum (IV)

This thesis describes the synthesis, structural studies, stoichiometric and catalytic reactivity of novel Mo(IV) imido hydride complexes (Cp)(ArN)Mo(H)(PMe3) (1) and (Tp )(ArN)Mo(H)(PMe3) (2). Both 1 and 2 catalyze hydrosilylation of a variety of carbonyls. Detailed kinetic and DFT studies found that 1 reacts by an unexpected associative mechanism, which does not involve Si-H addition either to the imido group or the metal. Despite 1 being a d2 complex, its reaction with PhSiH3 proceeds via a a-bond metathesis mechanism giving the silyl derivative (Cp )(ArN)Mo(SiH2Ph)(PMe3). In the presence of BPh3 reaction of 1 with PhSiH3 results in formation of (Cp)(ArN)Mo(SiH2Ph)(H)2 and (Cp)(ArN)Mo(SiH2Ph)2(H), the first examples ofMo(VI) silyl hydrides. AI: 1 : 1 reaction between 2, PhSiD3 and carbonyl substrate established that hydrosilylation is not accompanied by deuterium incorporation into the hydride position of the catalyst, thus ruling out the conventional mechanism based on carbonyl insertion carbonyl. As 2 is nomeactive to both the silane and ketone, the only mechanistic alternative we are left with is that the metal center activates the carbonyl as a Lewis acid. The analogous nonhydride mechanism was observed for the catalysis by (ArN)Mo(H)(CI)(PMe3), (Ph3P)2(I)(O)Re(H)(OSiMe2Ph) and (PPh3CuH)6. Complex 2 also catalyzes hydroboration of carbonyls and nitriles. We report the first case of metal-catalyzed hydroboration of nitriles as well as hydroboration of carbonyls at very mild conditions. Conversion of carbonyl functions can be performed with high selectivities in the presence of nitrile groups. This thesis also reports the first case of the HlH exchange between H2 and Si-H of silanes mediated by Lewis acids such as Mo(IV) , Re(V) , Cu(I) , Zn(II) complexes, B(C6Fs)3 and BPh3.

Half-sandwich Complexes of Ruthenium; Synthesis and Application to Catalysis

This thesis describes syntheses and catalytic reactivity of several half-sandwich complexes of ruthenium. The neutral ruthenium trihydride complex, Cp(PPri3)RuH3(1), can efficiently catalyse the H/D exchange reaction between various organic substrates and deuterium sources, such as benzene-d6. Moreover, the H/D exchange reactions of polar substrates were also observed in D2O, which is the most attractive deuterium source due to its low cost and low toxicity. Importantly, the H/D exchange under catalytic conditions was achieved not only in aromatic compounds but also in substituted liphatic compounds. Interestingly, in the case of alkanes and alkyl chains, highly selective deuterium incorporation in the terminal methyl positions was observed. It was discovered that the methylene units are engaged in exchange only if the molecule contains a donating functional group, such as O-and N-donors, C=C double bonds, arenes and CH3. The cationic half-sandwich ruthenium complex [Cp(PPri3)Ru(CH3CN)2]+(2) catalyses the chemoselective mono-addition of HSiMe2Ph to pyridine derivatives to selectively give the 1,4-regiospecific, N-silylated products. An ionic hydrosilylation mechanismis suggested based on the experiments. To support this mechanistic proposal, kinetic studies under catalytic conditions were performed. Also, the 1,4-regioselective mono-hydrosilylation of nitrogen containing compounds such as phenanthroline, quinoline and acridine can be achieved with the related Cp*complex [Cp*(phen)Ru(CH3CN)]+(3) (phen = 1,10-phenanthroline) and HSiMe2Ph under mild conditions. The cationic ruthenium complex 2 can also be used as an efficient catalyst for transfer hydrogenation of various organic substrates including carbonyls, imines, nitriles and esters. Secondary alcohols, amines, N-isopropylidene amines and ether compounds can be obtained in moderate to high yields. In addition, other ruthenium complexes, 1,3 and [Cp*(PPri3)Ru(CH3CN)2]+(4), can catalyse transfer hydrogenation of carbonyls although the reactions were sluggish compared to the ones of 2. The possible intermediate, Cp(PPri3)Ru(CH3CN)(H), was characterized by NMR at low temperature and the kinetic studies for the transfer hydrogenation of acetophenone were performed. Recently, chemoselective reduction of acid chlorides to aldehydes catalysed by the complex 2 was reported. To extend the catalytic reactivity of 2, reduction of iminoyl chlorides, which can be readily obtained from secondary amides, to the corresponding imines and aldehydes was investigated. Various substituted iminoyl chlorides were converted into the imines and aldehydes under mild conditions and several products were isolated with moderate yields.

Novel non phospholipid liposomes with high sterol content : development and characterization

Les liposomes sont des nanovecteurs polyvalents et prometteurs quant à leur utilisation dans plusieurs domaines. Il y a une décennie, un nouveau type de liposome constitué d’amphiphiles monoalkylés et de stérols est né fortuitement dans notre groupe. Ils sont nommés Stérosomes puisqu’ils contiennent une grande proportion de stérols, entre 50 et 70 mol %. Les objectifs de cette thèse sont de développer de nouvelles formulations de Stérosomes ayant des caractéristiques spécifiques et d’acquérir une compréhension plus profonde des règles physicochimiques qui dictent leur comportement de phase. Nous avons spécifiquement examiné le rôle de motifs moléculaires des stérols, de la charge interfaciale et de la capacité à former des liaisons H dans les interactions intermoléculaires menant à l’autoassemblage. Le comportement de phase a été caractérisé par calorimétrie différentielle à balayage (DSC), par spectroscopie infrarouge (IR) et par spectroscopie de résonance magnétique nucléaire du deutérium (²H NMR). Premièrement, nous avons établi certaines corrélations entre la structure des stérols, leur tendance à former des bicouches fluides en présence d'amphiphile monoalkylé et la perméabilité des grandes vésicules unilamellaires (LUV) formées. La nature des stérols module les propriétés de mélange avec de l’acide palmitique (PA). Les stérols portant une chaîne volumineuse en position C17 sont moins aptes à induire des bicouches fluides que ceux qui ont une chaîne plus simple, comme celle du cholestérol. Un grand ordre de la chaîne alkyle de PA est un effet commun à tous les stérols investigués. Il a été démontré que la perméabilité des LUV peut être contrôlée en utilisant des stérols différents. Cependant, ces stérols n’ont aucun impact significatif sur la sensibilité des Stérosomes au pH. Afin de créer des liposomes qui sont sensibles au pH et qui ont une charge positive à la surface, des Stérosomes composés de stéarylamine et de cholestérol (Chol) ont été conçus et caractérisés. Il a été conclu que l’état de protonation de l’amine, dans ce travail, ou du groupe carboxylique, dans un travail précédent, confère une sensibilité au pH et détermine la charge à la surface du liposome. Les premiers Stérosomes complètement neutres ont été fabriqués en utilisant un réseau de fortes liaisons H intermoléculaires. Le groupe sulfoxyde est capable de former de fortes liaisons H avec le cholestérol et les molécules d’eau. Une bicouche fluide métastable a été obtenue, à la température de la pièce, à partir d'un mélange équimolaire d’octadécyl méthyl sulfoxyde (OMSO) et de Chol. Ce comportement distinct a permis d’extruder le mélange pour former des LUV à la température de la pièce. Après 30 h, le temps de vie de la phase métastable, des Stérosomes stables et imperméables existaient toujours sous une forme solide. Un diagramme de température-composition a été proposé afin de résumer le comportement de phase des mélanges d’OMSO/Chol. Finalement, nous avons élaboré des Stérosomes furtifs en incorporant du polyéthylène glycol (PEG) avec une ancre de cholestérol (PEG-Chol) à l’interface de Stérosomes de PA/Chol. Jusqu’à 20 mol % de PEG-Chol peut être introduit sans perturber la structure de la bicouche. La présence du PEG-Chol n’a aucun impact significatif sur la perméabilité de la LUV. L'encapsulation active de la doxorubicine, un médicament contre le cancer, a été réalisée malgré la faible perméabilité de ces LUV et la présence du PEG à l’interface. L’inclusion de PEG a modifié considérablement les propriétés de l’interface et a diminué la libération induite par la variation de pH observée avec des LUV nues de PA/Chol. Cette formulation inédite est potentiellement utile pour l’administration intraveineuse de médicaments.

Els meus jocs : la creació de jocs a partir del folklore i la cultura de les Illes Balears. 'Mis juegos : la creación de juegos a partir del folklore y la cultura de las Islas Baleares'.

Resumen tomado del autor

La festa, memòria col·lectiva d’un poble. Cançons, balls i tonades de Manacor: un recurs a l’aula

Les manifestacions musicals dels actes festius de Manacor són el principal objecte d’estudi d’aquest treball, que pretén unir tres mons: la música i cultura tradicionals, la pedagogia i les noves tecnologies de la informació i la comunicació. Per entendre bé el significat de les cançons, balls i tonades que hem estudiat i organitzat seguint la roda de l’any, hem hagut d’endinsar-nos en les arrels de la nostra història i cultura per poder-les contextualitzar. El fil conductor han estat les festes populars, que guarden gran part de la memòria col·lectiva d’un poble. Hem afavorit l’ús pedagògic mitjançant fitxes d’anàlisi, aplicacions didàctiques i enregistraments de les cançons seleccionades, tot confiant que pugin servir de recurs per a qualsevol docent amb l’objectiu d’aprendre música i cultura tradicionals de Manacor i, per extensió, de les Illes Balears. La necessitat de facilitar el maneig del material que oferim en aquest treball i la voluntat de donar-li difusió han fet que prengués forma de pàgina web. Així, tota la informació —marc historicocultural, fitxes i enregistraments— està organitzada en format de web.