The thermal decomposition products (TDP) generated during fire suppression with 1,1,1,2,2,4,5,5,5 nonafluoro-4-trifluoromethyl pentan-3-one were studied using wet chemistry and FTIR. Small-scale testing was conducted in a 1.28-m3 (45-ft3) enclosure. The effects of fire size, agent discharge time, and agent concentration on TDP are reported. A comparison of the two methods is presented. In terms of magnitude and generation trends, the TDPs were found to be comparable to other in-kind halon alternatives.

DICLORO-α-(ALQUILTELURO)CETONAS Estudou-se a reação entre quantidades equimolares de cetonas ou éteres enólicos de silício de cetonas e tricloretos de alquil telúrio, obtendo-se dicloro-α-(organil) cetonas. Em todos os exemplos efetuados obtiveram-se bons resultados apenas nas reações com éteres enólicos de silício. TELURETOS VINíLICOS TRISSUBSTITUíDOS Neste trabalho desenvolvemos um método de preparação de teluretos vinílicos trissubstituídos, obtidos através da reação de adição de tricloreto de aril telúrio e tetracloreto de telúrio a acetilenos aromáticos e alifáticos, levando aos dicloretos de aril-2-clorovinila de configuração Z. A redução da ligação Te-Cl dos dicloroteluro compostos obtidos, levando aos teluretos correspondentes pode ser efetuada em alto rendimento pela reação com um equivalente de NaBH4. A halogenodeteluração destes teluretos vinílicos trissubstituídos foi possível reagindo-os com N-bromosuccinimida/cloreto de alumínio, obtendo-se bromocloroalquenos em rendimentos moderados. 1,1-DIHALO-2-(FENILSELENO)CICLOPROPANOS Outro tópico abordado foi a preparação de 1,l-dihalo(fenilseleno)ciclopropanos, por meio da adição de dihalocarbenos, gerados sob condições de transferência de fase, a selenetos vinílicos de configuração Z ou E. A adição ocorreu com retenção de configuração da ligação olefínica. Também foram preparados, empregando-se a mesma metodologia acima mencionada, selenociclopropanos tri- e tetrassubstituídos. / α- DICHLORO-(ORGANYLTELLURO)KETONES The reaction of equimolar amounts of ketones or ketone trimethylsilylenol ethers with aryltellurium trichlorides in boiling benzene produces α - dichloro-(aryltelluro) ketones in good yields. The reaction with aliphatic tellurium trichlorides give good results only with ketone silyl enol ethers; reaction with ketones gives low yields of the α-dichloro-(organyltelluro)ketones. VINYLIC TELLURIDES (p-Methoxyphenyl)tellurium trichlorides and tellurium tetrachloride react with terminal acetylenes to give 1-chloro-1-organyl-2-[dichloro(p-methoxyphenyl)telluro] ethenes of Z configuration in good yields. The diorganyl tellurium dichlorides are reduced to the corresponding tellurides with sodium borohydride. Halogenodetelluration of these trisubstituted vinylic tellurides was possible by reaction with N-bromosuccinimide/aluminium(III) chloride, producing the correspondent bromochloroalkenes in good yields. 1,1-DIHALO-SELENOCYCLOPROPANES Selenocyclopropanes were prepared by the addition of dihalocarbenes, generated under phase transfer conditions to Z and E disubstituted vinylic selenides. The addition occurs with retention of configuration of the olefinic bond. By employing the above mentioned methodology it was possible to prepare tri- and tetrasubstituted selenocyclopropanes.

<p>Transition metals have played an important role in synthetic organic chemistry for more than a century, and offer catalytic transformations that would have been impossible with classical chemistry. One of the most useful and versatile of the transition metals is palladium, which over the years has catalyzed many important carbon-carbon forming reactions. Popular cross-coupling reactions such as the Suzuki, Stille and the Heck reaction are all catalyzed by palladium, or more correctly, by palladium in its ground state, Pd(0). </p><p>Recently, interest in palladium(II)-catalyzed transformations has started to grow, partly due to the development of the vinylic substitution reaction, commonly called the oxidative Heck reaction, presented in this thesis. This Pd(II)-catalyzed, ligand-modulated reaction occurs under air at room temperature, and for the first time a general protocol employing a wide range of olefins and arylboronic acids was obtained. Ligand screening showed that the bidentate nitrogen ligand, 2,9-dimethyl-1,10-phenanthroline (dmphen), was the most suitable ligand. Dmphen is believed to facilitate regeneration of active Pd(II), increase catalytic stability and improve the regioselectivity in the reaction. A mechanistic investigation was conducted using electrospray ionization mass spectrometry (ESI-MS), making it possible to observe cationic intermediates in a productive oxidative Heck arylation. The results obtained are in agreement with the previously proposed catalytic cycle.</p><p>The emerging discipline of high-speed synthesis is making contributions to society’s growing demand for new chemical entities. This inspired the development of two ultrafast, microwave-accelerated carbonylation reactions with dicobalt octacarbonyl acting both as an in situ carbon monoxide supplier and reaction mediator. A wide range of symmetrical benzophenones was produced in only 6 to 10 s, using aryl iodides as the substrate. The second carbonylation reaction provided symmetrical and unsymmetrical ureas in process times ranging from 10 s to 40 minutes using primary and secondary amines.</p>

Transition metals have played an important role in synthetic organic chemistry for more than a century, and offer catalytic transformations that would have been impossible with classical chemistry. One of the most useful and versatile of the transition metals is palladium, which over the years has catalyzed many important carbon-carbon forming reactions. Popular cross-coupling reactions such as the Suzuki, Stille and the Heck reaction are all catalyzed by palladium, or more correctly, by palladium in its ground state, Pd(0). Recently, interest in palladium(II)-catalyzed transformations has started to grow, partly due to the development of the vinylic substitution reaction, commonly called the oxidative Heck reaction, presented in this thesis. This Pd(II)-catalyzed, ligand-modulated reaction occurs under air at room temperature, and for the first time a general protocol employing a wide range of olefins and arylboronic acids was obtained. Ligand screening showed that the bidentate nitrogen ligand, 2,9-dimethyl-1,10-phenanthroline (dmphen), was the most suitable ligand. Dmphen is believed to facilitate regeneration of active Pd(II), increase catalytic stability and improve the regioselectivity in the reaction. A mechanistic investigation was conducted using electrospray ionization mass spectrometry (ESI-MS), making it possible to observe cationic intermediates in a productive oxidative Heck arylation. The results obtained are in agreement with the previously proposed catalytic cycle. The emerging discipline of high-speed synthesis is making contributions to society’s growing demand for new chemical entities. This inspired the development of two ultrafast, microwave-accelerated carbonylation reactions with dicobalt octacarbonyl acting both as an in situ carbon monoxide supplier and reaction mediator. A wide range of symmetrical benzophenones was produced in only 6 to 10 s, using aryl iodides as the substrate. The second carbonylation reaction provided symmetrical and unsymmetrical ureas in process times ranging from 10 s to 40 minutes using primary and secondary amines.

The thesis entitled "Structure and reactivity in bridged polycyclic systems: cis-trans enantiomerism, fulvene cycloadditions and crystallographic studies of bridgehead β-ketoacids " consists of two parts. Part I contains 3 chapters, and deals with cycloaddition reactions of 6-arylfulvenes with maleic anhydride and nitrones (The products in the case of maleic anhydride display cis-trans enantiomerism). Part II contains 2 chapters, and deals with resolution of racemic primary amines, racemic amino acids and the relative decarboxylation propensities of bicyclic β-ketoacids in solid state. Part I Chapter 1: A new case of the uncommon cis-trans enantiomerism is presented in the Diels-Alder cycloadducts (3 & 4) of 6-arylfulvenes (1) with maleic anhydride (2).1 The resolution of the cis-trans enantiomers were accomplished via the formation of diastereomeric imides 6 and 7 with (1S)-(naphth-1-yl)ethylamine (5), and their subsequent hydrolysis and recyclisation (Scheme 1). The enantiomers 3 and 4 were characterized spectrally, polarimetrically (including CD) and by chiral HPLC. The chiral anhydrides were also stereospecifically converted to the corresponding imides by treatment with aq. ammonia in excellent yields. The crystal structure of one of the diastereomeric imides (derived from 6-phenylfulvene) was determined, and based on the known S configuration of the naphthylethylamine moiety, the configurations of the original anhydride adducts could be assigned.2 Scheme 1 Chapter 2: In this chapter tricyclic imides (8a-c) were prepared by Diels-Alder reaction of 6-arylfulvenes (1a-c) and maleic anhydride (2),2 followed by treatment with aq. NH3. The exo isomers were found to exist as conglomerates when the aryl group was p-tolyl or p-anisyl (although not phenyl). Triage of the p-tolyl racemate (Scheme 2), followed by reaction with p-toluenesulphonyl chloride in CH2Cl2/Et3N, led to the crystalline enantiopure N-tosylimides 9 (These were also found to be conglomerates). X-ray diffraction analysis of the N-tosylimides (9) via the anomalous dispersion technique led to the assignment of the absolute configurations (as either E or Z).3, 4 The original p-tolyl imide enantiomers were found to racemise upon UV irradiation in CHCl3. Based on this, a possible second order asymmetric transformation under photochemical conditions was attempted, and indeed led to the isolation of crystalline imide with a small ee (~15%).5 Scheme 2 Chapter 3: This chapter deals with the fulvene-nitrone cycloadditions. The possibility of discovering examples of the rare (6π + 4π) cycloaddition prompted an exploration of the reaction between electron-rich nitrones and pentafulvenes. In previous reports of such cycloadditions, diazomethane or benzonitrile oxide was used as 4π component.6 Building on previous work from this laboratory,7 the reaction between a set of substituted fulvenes and electron rich nitrones were studied. Theoretical calculations indicate that the (6π + 4π) mode would be favored when the fulvene-nitrone cycloaddition is controlled by the LUMO (fulvene) – HOMO (nitrones) interaction.8 Electron withdrawing groups on the fulvene would lower the LUMO and facilitate the above orbital interaction. Therefore the reaction between electron poor fulvenes and nitrones was taken up for further study. In particular, fulvene (10) was reacted with nitrones (11). However, only a (2π + 4π) mode was observed, involving one of the endocyclic double bond of the fulvene, in moderate yields (Scheme 3). Structures of these adducts were assigned based on NMR and X-ray crystal structure determination. The failure to observe the (6π + 4π) mode (14) is intriguing, and it is not clear whether this is due to electronic or steric reason. Scheme 3 Part II Chapter 1 describes the resolution of racemic primary amines and racemic amino acids (16) via the formation of diastereomeric imides. For this purpose D-camphoric anhydride (15) was chosen as the chiral auxiliary for the following reasons: it is of low-molecular weight with a rigid backbone, and is also easily prepared and purified.9 Primary amine (16) was treated with D-camphoric anhydride (15) in presence of CHCl3/DCC to form the corresponding diastereomeric imides 17 and 18. (In the case of amino acids, the corresponding methyl esters were treated with D-camphoric anhydride (15) in presence of triethylamine in chloroform). The resulting diastereomeric imides 17 and 18 were separated by silica gel column chromatography (Scheme 4), and hydrolyzed to the chiral amines (or amino acids). (The by-produced camphoric acid could be reconverted to D-camphoric anhydride (15). Scheme 4 Chapter 2: The relative ease with which β-ketoacids tend to lose CO2 is intriguing and has been the focus of numerous mechanistic studies.10-12 It is generally believed that the decarboxylation of β-ketoacids occurs via a six-centered hydrogen bonded transition state (19), which leads to the formation of the enol tautomer (20) of the final ketone product (Scheme 5). Scheme 5 Scheme 6 The initial formation of the enol is apparently supported by the high thermal stability of bicyclic β-ketoacids, in which the carboxylic acid functionality is at bridgehead. In these the formation of the enol would be disfavored by Bredt’s rule, which forbids the formation of a double bond at the bridgehead (particularly in the smaller bicyclic compounds). Also, it may be expected that these trends would be manifested in the ground state. This is because there would be a stereoelectronic requirement for the decarboxylation reaction, by which the bond to the carboxylic group would need to be parallel to the C=O π bond of the keto group. Therefore, it was of interest to study the crystal structures of suitable β-ketoacids in the hope of evidencing the above structural trends (Structure for the analogs 21-23 have been reported previously (Scheme 6)).13-15 In fact, the approach pioneered by Dunitz was of particular interest in this regard. 16 In this approach crystal structures of a series of analogs were studied; these analogs possess varying degrees of strain that could be considered as leading to the transition state of a certain reaction. The bond length and related data are then employed to ‘map’ the reaction dynamics. Compound Bond* lengths (Å) Increase in the bond length compared to ketopinic acid (%) Decarboxylation temp.17 * fine bond at the bridgehead to the COOH group. In the case of the decarboxylation of β-ketoacids, a correlation between the lengthening of the bond to the COOH group and the ease of decarboxylation was sought. Therefore the set of analogs 24-26 were prepared (Scheme 6) and their crystal structures determined by X-ray diffraction (at 100K). In the case of 26, an increase of 2.47% relative to 21 in the Cα-COOH bond length was observed. However, no evidence for an intramolecular O=C-O-H…O=C H-bonding, was observed in the crystal structures of 24-26. Instead, the COOH moieties were seen to participate in intermolecular O-H…O hydrogen bonding via the well known carboxylic acid dimer motif. The β-ketoacids were also converted into their corresponding S-benzylisothiouronium salts (Scheme 6), to study the effect of destroying the COOH dimer motif. The salts 27 and 28 could be obtained in a form suitable for single crystal X-ray diffraction. The crystal structures revealed an increase in the Cα-COO- bond length to an extent of 1.97% in case of 28 relative to 27. Also, there is an increase in the relevant bond length of ~0.8% on going from 24 (m.p. 145 °C) to 26 (m.p. 132 °C). Note also that these compounds melts with decompositions. Therefore, it appears that the ease of decarboxylation of these analogs is reflected in the relative lengthening of the bond to the COOH group. Thus, this study represents an application of the Dunitz crystallographic approach to reaction dynamics,16 to the case of the decarboxylation of β-ketoacids.(For structural formula pl see the pdf file)

Mechanistic studies on three different ruthenium-based catalysts have been performed. The catalysts have in common that they have been employed in hydrogen transfer reactions involving alcohols and ketones, amines and imines or both. Bäckvall’s catalyst, η5-(Ph5C5)Ru(CO)2Cl, finds its application as racemization catalyst in dynamic kinetic resolution, where racemic alcohols are converted to enantiopure acetates in high yields. The mechanism of the racemization has been investigated and both alkoxide and alkoxyacyl intermediates have been characterized by NMR spectroscopy and in situ FT-IR measurements. The presence of acyl intermediates supports a mechanism via CO assistance. Substantial support for coordination of the substrate during the racemization cycle is provided, including exchange studies with both external and internal potential ketone traps. We also detected an unexpected alkoxycarbonyl complex from 5-hydroxy-1-hexene, which has the double bond coordinated to ruthenium. Shvo’s catalyst, [Ru2(CO)4(μ-H)(C4Ph4COHOCC4Ph4)] is a powerful catalyst for transfer hydrogenation as well as for dynamic kinetic resolution. The mechanism of this catalyst is still under debate, even though a great number of studies have been published during the past decade. In the present work, the mechanism of the reaction with imines has been investigated. Exchange studies with both an external and an internal amine as potential traps have been performed and the results can be explained by a stepwise inner-sphere mechanism. However, if there is e.g. a solvent cage effect, the results can also be explained by an outer-sphere mechanism. We have found that there is no cage effect in the reduction of a ketone containing a potential internal amine trap. If the mechanism is outer-sphere, an explanation as to why the solvent cage effect is much stronger in the case of imines than ketones is needed. Noyori’s catalyst, [p-(Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3), has successfully been used to produce chiral alcohols and amines via transfer hydrogenation. The present study shows that the mechanism for the reduction of imines is different from that of ketones and aldehydes. Acidic activation of the imine was found necessary and an ionic mechanism was proposed.

Chiral cyclic alpha azido ketones are very important compounds in organic chemistry. Because, the reduced forms of them are amino alcohols and these amino alcohols are interesting compounds for their biological activities. They have some pharmaceutical activities such as: potassium channel open up properties, treatment of central nervous system, antihypertensive properties, the agent of dopamin receptor activator, hypolipemic agent and dopamine agonist. These types of compounds have highly acidic alpha-protons, and many kinds of reactions can be performed with them. In this study, mainly, selective protonation of racemic compounds was performed with a new practical method and there are not so many examples related to deracemization in the literature. Alpha-azido derivatives of tetralone, indanone, chromanone, and thiochromanone structures are chosen as starting materials because of their importance for biological activities arising from their cyclic structures. Firstly, these &alpha / -azido compounds were synthesized according to literature. The acidic alpha-protons do not require strong bases. Their enantioselective deracemization and deracemization processes were screened by using Cinchona derivatives as organocatalysts. This screening process was monitored by chiral HPLC columns. The parameters such as catalyst loading, solvent, temperature, reaction time and additives were optimized to obtain high enantioselectivities up to 98%. In addition to deracemization reactions, Michael addition reactions were also performed by starting from &alpha / -azido chromanones. In these reactions different type of urea catalyst was used to activate the electrophilic part of trans-&beta / -nitrostyrene compound. Again by controlling the temperature, time and catalyst loading, two diastereomers were formed and the screening process was monitored by chiral HPLC columns again. The Michael products were obtained in up to 94% ee and 75% yield.

Novel sol-gel titania-poly(dimethylsiloxane) (TiO2-PDMS) and titania-silica-N-(triethoxysilylpropyl)-O-polyethylene oxide urethane (TiO2-SiO2-TESP-PEO) coatings were developed for capillary microextraction (CME) to perform on-line preconcentration and HPLC analysis of trace impurities in aqueous samples. Due to chemical inertness of titania, effective covalent binding of a suitable organic ligand to its surface is difficult via conventional surface modification methods. In this research, sol-gel chemistry was employed to chemically bind hydroxy-terminated poly(dimethylsiloxane) (PDMS) and N-(triethoxysilylpropyl)-O-polyethylene oxide urethane (TESP-PEO) to sol-gel titania and sol-gel titania-silica network, respectively. A method is presented describing in situ preparation of the titania-based sol-gel PDMS and TESP-PEO coatings and their immobilization on the inner surface of a fused-silica microextraction capillary. To perform on-line CME-HPLC, the sol-gel TiO2-PDMS or TiO2-SiO2-TESP-PEO capillarywas installed in the HPLC injection port as an external sampling loop, and a conventionalHPLC separation column was used for the liquid chromatographic separation. The sol-gel TiO2-PDMS-coated microextraction capillary was used for on-line CME-HPLC analysis of non-polar and moderately polar analytes, and the sol-gel coatings showed excellent pH (1-13), and solvent (acetonitrile and methanol) stabilities under elevated temperatures (150 C) over analogous non-sol-gel silica-based coatings. Extraction of highly polar analytes, especially from aqueous phases is not an easy task. However, the sol-gel TiO2-SiO2-TESP-PEO-coated capillaries showed excellent capability of extracting underivatized highly polar analytes from aqueous samples. This opens the possibility to employ sol-gel titania-based polar coatings for solvent-free extraction and trace analysis of target analytes in environmental and biomedical matrices. To our knowledge, this is the first research on the use of sol-gel titania (or titania-silica)-based organic-inorganic materials as a sorbent in capillary microextraction. The newly developed sol-gel titania (or titania-silica)-based organic-inorganic hybrid extraction media provides an effective solution to coupling CME with HPLC (CME-HPLC), and this can be expected to become a powerful analytical tool in environmental investigations, proteomic research, early disease diagnosis and biomarker research. Being a combination of a highly efficient solvent free sample preconcentration technique (CME) and a powerful separation method (HPLC), CME-HPLC poses to become a key analytical tool in solving complex chemical, environmental, and biomedical problems involving complex matrices.

The development of the interrupted Nazarov cyclization of allenyl vinyl ketones is presented. The intermediate oxyallyl cation, derived from an allenyl vinyl ketone, may be trapped efficiently by a divergent array of nucleophilic species generating functionalized cyclopent-2-enone products. Allenyl vinyl ketones are also a versatile source of cyclic molecules via a tandem reaction sequence terminated via reaction with acyclic dienes, cyclic dienes, aza-heterocycles, electron-rich alkenes, or styrenes by the formation of an additional ring by a [4 + 3] and/or [3 + 2] cyclization or by the formation of one additional carbon-carbon bond. The bicyclic compounds generated by these processes are densely substituted, and would be difficult to access as succinctly in other ways. The products of these interrupted Nazarov reactions generally reflect excellent regio- and stereoselectivity in the trapping reaction. In some instances, equilibrating conditions were shown to enhance the proportion of one product at the expense of another or to provide a different carbon skeleton. This process appears fairly general, and can be conducted with unsubstituted or alkyl, aromatic, or heteroaromatic allenyl vinyl ketones. The exceptional affinity of allenyl vinyl ketones to undergo interrupted Nazarov reactions is likely a result of the increased longevity of the intermediate oxyallyl cation, due in part to the increased resonance stabilization provided by the allene unit. The high regioselectivity noted in the trapping process was computationally and experimentally confirmed to be a result of a localization of the positive charge in the intermediate oxyallyl cation. The application of this recently developed methodology towards the synthesis of the natural product (+)-roseadione is also described. The tandem Nazarov/[4 + 3] cascade of allenyl vinyl ketones provides a unique manner in which to access the tricyclic core of this cyclooctanoid natural product, a molecule which, to date, has never been synthesized.

Late transition metal complexes of silver(I), rhodium(I), ruthenium(II), palladium(II) and platinum(II) containing a nitrile-functionalized N-heterocyclic carbene ligand (C-CN) were prepared. The nitrile group on the C–CN ligand was shown to undergo hydrolysis under basic conditions, leading to a silver(I) carbene complex with a primary-amido functional group, and a trimetallic complex of palladium(II) with a partially hydrolyzed C–N–N–C donor ligand. The reduction of a nitrile-functionalized imidazolium salt in the presence of nickel(II) chloride under mild conditions yielded an axially chiral square-planar nickel(II) complex containing a unique primary-amino functionalized N-heterocyclic carbene ligand (C-NH2). A transmetalation reaction moved this chelating C–NH2 ligand from nickel(II) to ruthenium(II), osmium(II), and iridium(III), yielding important catalysts for the hydrogenation of polar double bonds. The ruthenium(II) complex, [Ru(p-cymene)(C–NH2)Cl]PF6 catalyzed the transfer and H2-hydrogenation of ketones. The bifunctional hydride complex, [Ru(p-cymene)(C–NH2)H]PF6, which contains a Ru–H/N–H couple showed no activity under catalytic conditions unless when activated by a base. The outer-sphere mechanism involving bifunctional catalysis of ketone reduction is disfavored according to experimental and theoretical studies and an inner-sphere mechanism is proposed involving the decoordination of the amine donor from the C–NH2 ligand. The ruthenium(II) complex [RuCp*(C–NH2)py]PF6 showed higher activity than the iridium(III) complex [IrCp*(C–NH2)Cl]PF6 in the hydrogenation of ketones. This ruthenium(II) complex also catalyzes the hydrogenation of an aromatic ester, a ketimine, and the hydrogenolysis of styrene oxide. We proposed an alcohol-assisted outer sphere bifunctional mechanism for both systems based on experimental findings and theoretical calculations. The cationic iridium(III) hydride complex, [IrCp*(C–NH2)H]PF6 , was prepared and this failed to react with a ketone in the absence of base. The crucial role of the alkoxide base was demonstrated in the activation of this hydride complex in catalysis. Calculations support the proposal that the base deprotonates the amine group of this hydride complex and triggers the migration of the hydride to the η5-Cp* ring producing a neutral iridium(I) amido complex. This system contains an active Ir–H/N–H couple required for the outer sphere hydrogenation of ketones in the bifunctional mechanism.