Micro- and millireactor technology for challenging batch reactions in organic chemistry

De interesse in microreactortechnologie van zowel de chemische procesindustrie als academische onderzoeksinstellingen is sterk toegenomen in de laatste decennia. De fijnchemie en farmaceutische industrie zijn steeds op zoek naar methoden om de efficiëntie van hun processen te verbeteren aangezien ze streven naar een duurzame productie en een afname van de ecologische voetafdruk van hun processen. Microreactortechnologie kadert binnen het concept van groene chemie waardoor deze opkomende technologie de duurzaamheid van een productieproces kan verhogen. Microreactortechnologie biedt een aantal specifieke voordelen in vergelijking met traditionele batch chemie. Een verbeterde massa- en warmtetransfer, een veiligere manipulatie van toxische en reactieve reagentia en een eenvoudige opschaling zijn de belangrijkste voordelen. Schattingen geven aan dat ongeveer 44% van de chemische reacties baat kunnen hebben bij het gebruik van microreactortechnologie. In dit doctoraatsonderzoek werden een aantal reacties bestudeerd die voordeel kunnen halen uit de intrinsieke eigenschappen van microreactortechnologie. In een eerste deel van dit werk werd de condensatie van zuurchloriden en alcoholen zonder katalysator geoptimaliseerd in een microreactor. De reactie werd vervolgens opgeschaald naar een millireactor waarbij een deel van het vrijgestelde HCl gerecupereerd kon worden als waterige oplossing. In een tweede deel van dit doctoraatsonderzoek werd de tribromering van methylsulfonen en methaansulfonaten met hypobromiet in een water – tolueen tweefasensysteem geëvalueerd. Twee verschillende reactorsystemen werden vergeleken: een buisreactor en een statische menger. Uiteindelijk kon ook de synthese van hypobromiet continu uitgevoerd worden m.b.v. een CSTR (continuous stirred tank reactor) waardoor de synthese van hypobromiet en de daaropvolgende tribromering gekoppeld konden worden. In een derde luik van deze doctoraatsthesis werd de Simmons-Smith cyclopropanering van enaminen onderzocht. Na uitgebreide optimalisatie van de reactie konden zowel de synthese van het carbenoïde als de daaropvolgende Simmons-Smith cyclopropanering continu uitgevoerd worden in een microreactor. De isolatie van de gesynthetiseerde cyclopropylaminen was echter moeilijk. In een voorlaatste project werd de synthese van N-vinyl-2,2-bisfosfonoaziridines onderzocht door reactie van de overeenkomstige 1,1-bisfosfono-2-aza-1,3-diënen met diazomethaan. De invloed van microreactortechnologie en licht op de selectiviteit van de reactie werd onderzocht. In een laatste luik van dit doctoraatsonderzoek werd de activering van aminozuren met 1H-benzotriazool onderzocht. Door keuze van het juiste solvent kon de activering succesvol uitgevoerd worden in een mesoreactor

Kinetics and coverage dependent reaction mechanisms of the copper atomic layer deposition from copper dimethylamino-2-propoxide and diethylzinc

Atomic layer deposition (ALD) has been recognized as a promising method to deposit conformal and uniform thin film of copper for future electronic devices. However, many aspects of the reaction mechanism and the surface chemistry of copper ALD remain unclear. In this paper, we employ plane wave density functional theory (DFT) to study the transmetalation ALD reaction of copper dimethylamino-2-propoxide [Cu(dmap)2] and diethylzinc [Et2Zn] that was realized experimentally by Lee et al. [ Angew. Chem., Int. Ed. 2009, 48, 4536−4539]. We find that the Cu(dmap)2 molecule adsorbs and dissociates through the scission of one or two Cu–O bonds into surface-bound dmap and Cu(dmap) fragments during the copper pulse. As Et2Zn adsorbs on the surface covered with Cu(dmap) and dmap fragments, butane formation and desorption was found to be facilitated by the surrounding ligands, which leads to one reaction mechanism, while the migration of ethyl groups to the surface leads to another reaction mechanism. During both reaction mechanisms, ligand diffusion and reordering are generally endothermic processes, which may result in residual ligands blocking the surface sites at the end of the Et2Zn pulse, and in residual Zn being reduced and incorporated as an impurity. We also find that the nearby ligands play a cooperative role in lowering the activation energy for formation and desorption of byproducts, which explains the advantage of using organometallic precursors and reducing agents in Cu ALD. The ALD growth rate estimated for the mechanism is consistent with the experimental value of 0.2 Å/cycle. The proposed reaction mechanisms provide insight into ALD processes for copper and other transition metals

The crystal structures of some coordination compounds of group II metals

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New Routes to II-VI Materials

PhDZinc and cadmium dithiocarbamates were synthesized and used as single molecule precursors for the deposition of zinc or cadmium chalcogenides. The precursors were based on trimethylpropylenediamine including bis(trimethylpropylenediaminedithiocarbamato) zinc(lll)\cadmium(II) (3), (4) and methyl(trimethylpropylenediaminedithiocarbamato) zinc(III)\cadmium(II) (5), (6). These compounds have been chracterized by I. R, NMR ('H, 13Ca nd 11C3 d) and mass spectrometry. The c,ý sU*7 structures of bis(U-imethylpropylenediminedthiocarbamato)zinc(III) (3) and methyl- (ft-imethylpropylenediaminedithiocarbamato)cadmium (H) (6) have been determined, both compounds were polymeric. Thin films of zinc or cadmium sulfide by MOCVD method have been grown from (3), (4), (5) and (6). The cadmium compounds gave good films on both glass and GaAs substrates, but the films grown from corresponding zinc compounds were of poorer quality. Some t-butyl- and neopentyl(di-alkylamido)zinc compounds have been synthesized and characterized. Thin films of CdS, ZnS, CdZni-. S, and ZnO were grown by chemical bath deposition method. US films were deposited by using cadmium/ethylenediamine- /thiourea system whereas ZnS films were grown from zinc/ammonia/hydrazine/thiourea system. Films of ternary Cd,, Znl-,, S have been obtained by the addition of cadmium to the ZnS system. Calculation were carried out for the speciation of the solution for which US was deposited. Films of ZnO were deposited from solution containing zinc/ethylenediamine in presence of NaOH. The various parameters controlling the film quality, growth rates, morphology and crystallinity were investigated. The films deposited were characterized by several methods including scanning electron microscopy, tramission electron microscopy, X-ray powder diffraction, reflection high energy electron diffraction and the electronic spectroscopy.B.P. Solo

Azomethine derivatives of some metals and metalloids

This thesis describes the preparation of some methyleneamino derivatives of beryllium, zinc, gallium and silicon. The structural, implications of their infra-red spectra and nuclear magnetic resonance spectra are discussed. As a background to the work, the characteristics of such compounds are discussed in the Introduction, and in greater detail in each chapter. Di-t-butylmethyleneaminolithium reacts with beryllium chloride giving dimeric di-t-butylmethyleneaminoberyllium chloride, (Bu(^t)(_2)C:NBeCl)(_2), and the lithium beryllates Li(_n)Be(N:CBu(^t)(_2))(_2+n) (n = 1,2). Bis(di-t-butylmethyl-eneamino)beryllium, [(Bu(^t)(_2)C:N)(_2)Be](_2) was inaccessible by this route but was prepared by reacting di-t-butylmethyleneamine with di-isobutylberyllium (2:1). The crystal structure of this compound shows that the terminal CNBe unit is nearly linear and that the Be-N bond is relatively short, appropriate for N →Be (p → p) π-bonding. The structure determination supports the postulate that a high azomethine stretching frequency, v(C=N) is indicative of a linear CNBe unit and Be-N multiple bonding. Attempts to prepare adducts with trimethylamine and tetramethylethylene-diamine were unsuccessful. Reaction between methyleneamines and dialkylberylliums afford the derivatives (R(^2)C:NBeR’)(_2) (R = Bu(^2), Ph; R' = Bu(^i) and R = Ph; R' = Bu(^t)). A new monomeric compound, di-t-butylmethyleneamino-bis(trimethylsilyl)-aminoberyllium, Bu(^t)(_2)C:NBeN(SiMe(_3))(_2) was prepared and characterised. Reactions of zinc chloride with one or two moles of di-t-butylmethyl-eneaminolithium give dimeric iminozinc compounds, (Bu(^t)(_2)C:NZnCl)(_2) and [(Bu(^t)(_2)C:N)(_2)Zn](_2). A high azomethine stretching frequency in the latter compound is attributed to significant pπpπ interaction between zinc and nitrogen. Dimethylzinc reacts with one or two moles of di-t-butylmethyl-eneamine giving [(Bu(^t)(_2)CN)(_n)ZnMe(_2-n)])_2) (n = 1,2). Reaction between di-t-butylmethyleneaminolithium and gallium trichloride affords the compounds Li(_n)Ga(N: CBu(^t)(_2))(_3+n) (n = 0,1,2). Bis(di-t-butylmethyleneamino)gallium chloride could not be isolated, presumably through disproportionation to the mono- and tris-derivatives. A high azomethine stretching frequency, v(C=N), for (Bu(^t)(_2)C:N)(_3)Ga, is taken as evidence for a linear C=N-Ga skeleton with appreciable N=Ga π-bonding. The phenyl analogue (Ph(_2)C:N)(_3)Ga was prepared by a similar method. Equimolar proportions of diphenylmethyleneaminolithium and chlorosilanes Me(_n)SiCl(_4-n), (n = 0,1,2) afford the diphenylmethy1eneamino-silanes (Ph(_2)C:N)(_2)-SiM(_n)Cl(_3-n), apparently through disproportionation of the mono-substituted compounds Ph(_2)C:NSiMe(_n)Cl(_3-n), which could only be isolated when n = 2. The spectra of these compounds show that these may have bent C:NSi skeletons. Preliminary investigations into transition metal systems (R(_2)C:N)(_3)M (M = Fe; R = Bu(^t),Ph and M = Cr; R = Bu(^t)) are discussed in an appendix

Synthese neuartiger Liganden ausgehend von 5/6/5-Heterozyklen

Im Mittelpunkt der hier vorliegenden Dissertationsarbeit standen die Reaktionen der Bisthiadiazolo-triaziniumsalze (5/6/5-Heterozyklen) mit verschiedenen Stickstffnukleophilen. Von besonderem Interesse waren dabei die Reaktionen von 2-hydroxyphenylsubstituierten 5/6/5-Heterozyklen, da sich deren Reaktivität bekannter Weise von derer ihrer Analoga abhebt. Die Umsetzungen der 5/6/5-Heterozyklen mit Stickstoffnukleophilen wurden bezüglich der Selektivität und Produktvielfalt genau untersucht. Anhand einiger Vertreter wurden die Komplexeigenschaften der neuen Verbindungen untersucht

Complexes of unsaturated and other organoberyllium compounds

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I The tandem chain extension-acylation reaction II Synthesis of papyracillic acid A: Application of the tandem homologation-acylation reaction III Synthesis of tetrahydrofuran-based peptidomimetics

A zinc-mediated tandem chain extension-acylation reaction was successfully developed. This reaction was optimized with the use of beta-keto esters, amides, and imides as well as a variety of acylating agents. The tandem homologation-acylation reaction was successfully applied towards the total synthesis of papyracillic acid A. Use of a tandem chain extension-aldol reaction, followed by a reductive cyclization, allowed for the synthesis of tetrahydrofuran-based peptidomimetics. A variety of amino acid derived beta-keto imides and aldehydes were used during the initial tandem homologation-aldol reaction. High diastereocontrol was achieved during reductive cyclization when a cis relationship was present between the substituents on the tetrahydrofuran ring. Use of beta-keto imides during the chain extension reaction was important as they led to the formation of the required anti-aldol products