Part I Chemical Basics

Applied Homogeneous Catalysis, First Edition. Arno Behr and Peter Neubert. Ó 2012 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2012 by Wiley-VCH Verlag GmbH & Co. KGaA.

1 Definition, Options, and Examples

What Actually Is Catalysis?

1.1 be obtained in quantitative amounts. In Definition of Catalysis this case, the sulfuric acid serves as a catalyst. Let us consider a reversible chemical reac- Another example is the highly exother- tion between the educts A and B which leads mic reaction of the two gases hydrogen and to the products C and D: oxygen. In a sealed vessel, they can be mixed to any ratio without reaction, but if a small A þ B K C þ D ð1:1Þ amount of a platinum sponge is added to the mixture it reacts spontaneously. The cata- A typical example is the formation of an lyst, with its large surface area, initiates the ester from a carboxylic acid and an alcohol, so-called hydrogen–oxygen reaction: which involves the elimination of water, þ : K ð : Þ while the reverse reaction involves the H2 0 5O2 H2O 1 3 hydrolysis of an ester to a carboxylic acid and an alcohol: The reaction heat indicates a thermody- namically permitted reaction that will pro- 0 0 RCOOHþR OHKRCOOR þH2O ceed even at room temperature and at low ð1:2Þ pressure. This reaction also requires a catalyst – the transition metal, platinum – to get The steady state of this reaction – it started: only the catalyst is able to run the depending on pressure and temperature – reaction. is controlled by Nature and determined The adjuvant effect of the platinum by the thermodynamics (cf. Chapter 10). sponge was ﬁrst discovered by Johann Therateatwhichequilibriumisachieved Wolfgang D€obereiner (Figure 1.1) who, on is described by kinetics (cf. Chapter 11). the 27th of July 1823, used a platinum As is well known from organic chemistry, sponge to construct a gas lighter (Fig- the reaction requires a small amount of ure 1.2). In the lighter, the crank, e, is used sulfuric acid to get it started. Then, if the to dip a piece of zinc into a tank, c, which water produced is removed constantly contains sulfuric acid; this leads to the from the reaction vessel, the ester can formation of hydrogen (Eq. (1.4)):

Applied Homogeneous Catalysis, First Edition. Arno Behr and Peter Neubert. Ó 2012 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2012 by Wiley-VCH Verlag GmbH & Co. KGaA. 4j 1 Definition, Options, and Examples

namesake, Goethe, who initially had problems using it. In 1828, Goethe wrote to Dobereiner:€ Ew. Hochwohlgeboren haben die Gefalligkeit€ gehabt, einen dem Anblick und Zweck nach sehr anmutigen Apparat zuzusenden, aber ich will nur gestehen, daß Figure 1.1 Johann ohngeachtet der genauen beigefugten€ Wolfgang Dobereiner.€ Beschreibung ich doch das Experiment nicht zu unternehmen getraue. þ 2 þ Zn þ 2H ! Zn þ H2 ð1:4Þ (Approximate English translation: Your honor has been so kind to send me the very The hydrogen is first collected in an charming apparatus; however, I have to upright pipe and then released from the admit that I dont feel able to carry out the pipes upper end through a simultaneously experiment.) opened valve. The hydrogen is mixed with However, some time later Goethe is said oxygen from the ambient air and ignited by to have used the lighter on a regular basis. a piece of platinum sponge, f, attached The first definition of a catalyst was pro- immediately above the valve. The first auto- vided in 1836 by the Swedish chemist Jons€ matic gas lighter had been invented! Jakob Berzelius (Figure 1.3) of the Univer- Dobereiner€ gave one of these lighters to his sity of Stockholm, who noted that:

The substances that cause the

decomposition of H2O2 do not achieve this goal by being incorporated into the new

compounds (H2O and O2); in each case they remain unchanged and hence act by means of an inherent force whose nature is still unknown...

(Berzelius meant that, in the case of the hydrogen–oxygen reaction, the substance – the platinum sponge – would waken the dozing gases hydrogen and oxygen.

Figure 1.3 Jons€ Jakob Figure 1.2 Dobereiner€ s gas lighter. Berzelius. 1.2 The Different Varieties of Catalysis j5

Figure 1.4 The Chinese character for catalysis and matchmaker (tschu mei). Figure 1.5 A general catalysis cycle.

Moreover, this action can be repeated many However, he was unclear about the details of thousands or even millions of times. The the processes driven by the catalyst.) most commonly used method used to rep- Berzelius used the term katalysis, which resent this behavior graphically is a circle; is derived from the Greek, meaning to this is often referred to as catalytic cycle. untie, and on that basis he considered the A generalized type of cycle incorporating bond-breaking stage to be the crucial step. In the addition reaction A þ B ! A B, cat- contrast, the Chinese took a somewhat dif- alyzed by C, is shown in Figure 1.5. ferentapproachtocatalysis;theChinesechar- Here, the catalyst C first adds reactant acter tschu mei (Figure 1.4) means both A and, subsequently, also reactant B. The two catalysis and marriage broker, with the reactantsare unitedinthe immediate vicinity emphasis being placed much more on the of the catalyst (the marriage broker), such linking properties. that a new product, A–B, is formed. The fi When considering todaysde nition of a catalyst remains in the condition it was in catalyst: at the start of the cycle and, therefore, is available for another cycle. . A catalyst is a substance that increases the rate at which a chemical system 1.2 reaches its equilibrium. The Different Varieties of Catalysis . A catalyst participates in a chemical reaction, but is not itself consumed. The reaction in Eq. (1.2) contains liquid reactants – carboxylic acid and alcohol – Although, in theory, a catalyst should be which are reacted to produce a liquid ester active for ever, there is of course no ideal in the presence of liquid sulfuric acid. All of philosophers stone. Whilst each catalyst the components are completely soluble and, has a certain lifetime, during which it will as there is only one homogeneous liquid catalyze a reaction in an economical fashion, phase in the vessel, this is referred to as its efficiency will decrease steadily until, homogeneous catalysis. ultimately, it is dead. The lifetime of a In contrast, in Eq. (1.3) two gases react catalystmaybeveryshort,oritmaybeseveral in the presence of a solid catalyst, the years (this point is described in detail in platinum sponge. In this type of catalysis Chapter 4). there are at least two phases, and some- One factor that all catalysts have in com- times even three (gaseous, liquid, and mon is that, immediately after they have solid). Based on such heterogeneity, this successfully catalyzed a first reaction, they variant is referred to as heterogeneous are available to catalyze another reaction. catalysis. 6j 1 Definition, Options, and Examples

Table 1.1 Comparison of homogeneous and heterogeneous catalysis.

Criterion Heterogeneous catalysis Homogeneous catalysis

Catalyst stoichiometry Often undefined Common Catalyst structure Often undefined Common Catalyst variability Little Very variable Catalyst reproducibility Often difficult Very high Mechanism knowledge Often very little Available Number of active centers Only surface atoms All metal atoms Catalyst activity Different High Catalyst selectivity Usually poor Usually high Diffusion problems Present Barely present Conditions Often harsh Usually mild Catalyst lifetime Different Different Deactivation through poisoning Common Rarely Separation and recycling Usually easy Difficult

There are, however, different subtypes of heterogeneous catalysis (see Table 1.1). the two variants, depending on the type of Unfortunately, however, homogeneous catalyst being used. transition metal catalysis has one inherent disadvantagethatderivesfromitsdefinition; Homogeneous catalysts These can be: that is, as all of the reactants, catalysts and . soluble acids or bases ) homogeneous products are in the same homogeneous acid/base catalysis phase during reaction, any subsequent sep- . organic compounds ) homogeneous aration of the catalyst for its reuse can bevery organocatalysis difficult. Catalyst separation is, nonetheless, . soluble enzymes ) homogeneous essential as the typically very expensive tran- enzyme or biocatalysis sition metal catalyst must be recycled . soluble transition metal salts or soluble uncompromisingly for economic reasons, transition metal complexes ) and not discharged with the product. homogeneous transition metal catalysis. Likewise, for ecological reasons, neither the transition metal compounds nor any Heterogeneous catalysts These can be: associated organic compounds must be . insoluble acids or bases ) released into the environment. For exam- heterogeneous acid/base catalysis ple, although nickel is an important catalyst . solid immobilized enzymes ) metal, many people will suffer an allergic heterogeneous enzyme catalysis response if they come into contact with it. . solid metals or metal oxides ) Because of these problems, several chapters heterogeneous metal catalysis. of this book relate to separation concepts associated with homogeneous catalysis (see The main subject of this book is homoge- Chapters 14 to 18). neous transition metal catalysis, which pro- Homogeneous transition metal catalysts are vides excellent opportunities for both gentle usually well-defined compounds; typically, andselectivereactions.Infact,suchcatalysis their chemical composition is well known offers a range of benefits compared to and their structure can be determined easily 1.2 The Different Varieties of Catalysis j7

Figure 1.7 Fritz Haber. Figure 1.6 Geoffrey Wilkinson. surface and in the pores during reaction are not exactly known. The production of hetero- by using various spectroscopic methods. geneous catalysts is largely the domain of a Such catalysts can be synthesized according few manufacturers that have an extensive, to definite, reproducible synthetic protocols. mostly empirically acquired, know-how of A typical example of a homogeneous tran- catalyst synthesis. The optimal reaction con- sition metal catalyst is Wilkinsons catalyst ditions for the ammonia catalyst are quite [Rh(PPh3)3Cl], named after the Nobel prize harsh (350–520 C, 300 bar), and it can be laureate Sir Geoffrey Wilkinson (Figure 1.6), easily deactivated by catalyst poisons such from Imperial College, London. This catalyst as carbon monoxide or sulfur compounds. can be easily and reproducibly prepared in The main advantage of the process, however, high yields from rhodium trichloride is the good separability of the product and hydrate and triphenylphosphine PPh3 in catalyst; the solid catalyst remains in the ethanol. Furthermore, variations can easily reactor, while the gaseous ammonia is easily be achieved in its electronic and steric prop- collected. erties, by using different phosphine ligands. Homogeneous and heterogeneous catal- Moreover, its functionality – for example, in ysis have complementary positions in the the hydrogenation of olefinic double bonds – chemicalindustry.Forexample,manymajor has been investigated thoroughly, due industrial products such as gasoline, sulfu- mainly to the good analytical options avail- ric acid and nitric acid are produced via able during homogeneous catalysis (see heterogeneous catalysis, whereas many Chapter 12). basic chemicals and fine chemicals, phar- Atypicalexampleofa heterogeneouscatalyst istheammonia catalyst,whichcatalyzesthe conversion of hydrogen and nitrogen into ammonia. This was developed by the Nobel prize laureate Fritz Haber (Figure 1.7), at the Kaiser-Wilhelm-Institut in Berlin, and later applied to the industrial process by Carl Bosch, at BASF (Figure 1.8), who was also awarded the Nobel prize. The ammonia catalyst consists mainly of iron in combination with various adjuvants, and is very difficult to analyze during its application in the reactor. The structural conditions on the catalyst Figure 1.8 Carl Bosch. 8j 1 Definition, Options, and Examples

[cat.] H + CO, H2 Hydroformylation (1.5) O of alkenes

[cat.] + + Alkene metathesis (1.6)

X Z [cat.] C-C coupling + Z + HX (1.7) (Heck)

Figure 1.9 Reactions, which are only possible with transition metal catalysis.

maceuticals and agrochemicals are pro- reaction conditions) alkanes, alkenes, or duced via homogeneous catalysis. Transi- long-chain alcohols. tion metal catalysts enable reactions that, . Copper/zinc catalysts lead almost normally, cannot be carried out in any exclusively to methanol. other way; examples include hydroformyla- . Ethylene glycol can be produced by using tions (Eq. (1.5)), metathesis (Eq. (1.6)), or ruthenium catalysts. CC-coupling reactions (Eq. (1.7)) (Fig- . Nickel catalysts afford an entire ure 1.9). Each of these reactions is described methanization to methane. in detailin Section 1.3(seealso Chapters19– 31). In these descriptions, the abbreviation Hence, the chemical industry is in the [cat] is placed above the reactions arrow to position to prepare a wide product range indicate that it must be catalyzed; occasion- from the same material basis, simply by ally, other abbreviations such as [Pd] or [Rh] selecting the most suitable catalyst. are also shown, to indicate palladium- or The examples in Figure 1.10 relate almost rhodium-catalyzed reactions. exclusively to heterogeneous catalysis (except for the example of glycol synthesis), which frequently employs different metals, 1.3 or their combination. The homogeneous The Directing Effect of the Catalyst transition metal catalysis offers still another variation possibility, namely the choice of The catalyst not only has the property to different complex ligands. This is illustrated permit a reaction to proceed at all, but in in Figure 1.11 by the example of butadiene most cases it also has the ability to direct the cyclooligomerization (cf. Chapter 22) where- reaction towards certain products. A typical by, using the same catalyst metal (i.e., example of this is the various reaction pos- nickel) a diversity of butadiene oligomers sibilities of synthesis gas (a mixture of carbon can be produced, simply by altering the monoxide and hydrogen), as shown in ligand sphere: Figure 1.10: . . Aqueous iron/chromium or copper Tricyclohexylphosphine (PCy3)leads catalysts convert synthesis gas and water predominantlyto4-vinyl-1-cyclohexene(1). . to carbon dioxide and hydrogen. Triphenylphosphite (P(OPh)3) produces . Iron- or cobalt-containing Fischer– the eight-membered ring molecule 1,5- Tropsch catalysts lead to (depending on cyclooctadiene (2). 1.3 The Directing Effect of the Catalyst j9

Water gas shift reaction (+H O) 2 Hydrogen [Fe/Cr] or [Cu], –CO2

Alkanes Fischer–Tropsch reactions Alkenes [Fe] or [Co] Alcohols, carboxylic acids

CO + H2 Methanol synthesis CH3OH Synthesis gas [Cu/Zn]

Glycol synthesis HO–CH2–CH2–OH [Ru]

Methanization CH4 [Ni]

Figure 1.10 Catalytic control of synthesis gas reactions.

. With nickel bis(acrylonitrile) and

aluminum triethyl AlEt3 the 12- membered ring (3) is formed. . Nickel allyl complexes form the higher homologues (4). . 5 The palladium catalyst Pd(ClO4)2 can yield the four-membered ring (5). . The ﬁve-membered ring (6) is formed n when using [NiCl(ortho-tolyl)(PEt ) ]. 6 4 3 2 Again, several products can be derived from a single substrate, although the eight- and 12-membered rings are particularly important from an industrial aspect. The controlling possibilities of the ligands are 1 discussed in detail in Chapters 7 and 9, 3 while the monitoring of reactions is detailed 2 in Chapter 4, which incorporates the target Figure 1.11 The cyclic oligomers of butadiene. sizes of catalytic reactions. 10j 1 Definition, Options, and Examples

1.4 unnecessary burden on the environment. Catalysis as a Part of Green Chemistry In contrast, a novel catalytic pathway of ibuprofen synthesis – as elaborated by As catalysis provides the ability to produce a Hoechst–Celanese (Figure 1.12, right) – desired product without unquestioned contains only three reaction steps, without byproducts, it can be seen as a cornerstone the formation of considerable quantities of green chemistry, the important princi- of salt: ples of which include: . The prevention of waste. . The first step – the acylation of . The products shall contain the maximal isobutylbenzene in the para position – is proportion of reactants; that is, the still catalyzed by homogeneous acid reaction is to be atom-economic. catalysis. . The reactions must function with . In the second step, the keto group is increased energy efficiencies. hydrogenated to an alcohol by . The usage of renewable feedstocks is heterogeneous catalysis. The catalyst possible. used is recyclable palladium on carbon . Any derivatization reactions, such as the [Pd/C]. need for blocking or protecting groups, . The third step includes carbonylation of should be avoided. the hydroxyl group, leading to the . Catalytic agents are superior to carboxylic acid by means of carbon stoichiometric agents. monoxide. The catalyst is a homogeneous palladium complex. Homogeneous transition metal catalysis, in particular, meets such demands, for So, ibuprofen has been synthesized after example, it allows the direct CC-bonding only three steps, and all of the reactants of different building blocks without any used – except, of course, the catalysts! – needlessintermediatesteps(seeChapter19). are present in the final product. Such catalysis usually functions under mild reaction conditions, such as low tempera- tures (room temperature to 150 C) and low 1.5 pressures. It is also suitable for the conver- Sources of Information about Catalysis sion of renewables (as will be described in Chapter 38). When working through this book, a litera- An example from the chemical industry ture annex will be found at the end of each can be used to demonstrate the above-stat- chapter, which cites a small selection of ed principles. After a heavy nights drink- reasonable books, reviews and important ing, pills containing ibuprofen can help in reports. In the appendix of this Chapter, the the recovery from a hangover. Ibuprofen is details are provided of several well-known conventionally synthesized from isobutyl- textbooks and reference books, that will benzene in a six-step synthesis (Fig- help to deepen the knowledge of homoge- ure1.12,left);threeofthesixstepsinvolve neous transition metal catalysis. Brønsted or Lewis acids, while the two In order to be kept up to date, however, it other steps require bases. This leads inev- is essential to monitor relevant catalysis itably to the production of large quantities journals, the following of which are recom- of salts, the disposal of which may create an mended by the authors. 1.5 Sources of Information about Catalysis j11

catalytic route classic route Ac2O (Hoechst-Celanese) AlCl3 isobutylbenzene

Ac2O HF

base ClCH2COOEt O O

COOEt

+ H2O / H

CHO H2 catalytic [Pd/C] hydrogenation

NH2OH

NOH OH

- H2O

CO catalytic CN [Pd2+] carbonylation

H2O COOH H+

- 6 Steps Ibuprofen - 3 steps - intense salt formation - 100% atom economically

Figure 1.12 Comparison of synthesis methods of ibuprofen.

Homogeneous transition metal catalysis: Organometallic chemistry and homoge- . Journal of Molecular Catalysis A: neous transition metal catalysis: Chemical . Journal of Organometallic Chemistry . Advanced Synthesis and . Applied Organometallic Chemistry Catalysis . Organometallics 12j 1 Definition, Options, and Examples

. Transition Metal Chemistry . Platinum Metals Reviews (online: www. . Advances in Organometallic Chemistry platinummetalsreview.com) . Topics in Organometallic Chemistry . Accounts of Chemical Research . Coordination Chemistry Reviews . Journal of Organic Chemistry . Chemie-Ingenieur-Technik . Science Catalysis (general, but especially . ChemSusChem heterogeneous): . Dalton Transactions . ACS Catalysis . Chimia . Catalysis Science & Technolog Today . Advances in Catalysis Toensurethatnoimportantﬁndingsarebe . Applied Catalysis A: General missed, it is useful to subscribe to Catalysts . Catalysis Letters and Catalyzed Reactions, which is published . Catalysis Reviews: Science and by the Royal Society of Chemistry (see: www. Engineering rsc.org/catalysts). This abstract journal is . ChemCatChem published 12 times each year in both print . Catalysis Communications and electronic format, and contains (very short!) summaries of recent key publications Journals which often also report on on catalysis. A general example is given in catalysis: Figure 1.13, which contains only the title, . Angewandte Chemie authorsandsource,besidesatypicalreaction, . Chemistry – A European Journal the catalyst, and important reaction condi- . Journal of the American Chemical Society tionsandresults.Ifanarticle isinteresting,of . Chemical Communications course, the original report must also be con- . Green Chemistry sidered. The abstracts are indexed by type of . Chemical Reviews reaction, comparable to Part III of this book. . Synthesis So, if the details of only certain reactions are . Organic Letters being sought, it is possible to examine the . Tetrahedron relevant subsections in selective fashion. . Tetrahedron Letters

11848 Coinage metal complexes with N-heterocyclic carbene ligands as selective cataysts in diboration reaction R. Corberan; J. Ramirez; M. Poyatos; E. Peris*: E. Fernandez* Tetrahedron: Asymmetry, 2006, 17(12), 1759-1762

OH Au complex Cl Cl (i) Au complex OH n-ButN NBut-n THF, 25 ºC, 60 h O O BB O O Au (ii) NaOH, H2O2 n-ButN NBut-n 4 examples (13–100% conversion) 94% conversion Cl Cl

Figure 1.13 Constitution of a graphical abstract in Catalysts and Catalyzed Reactions. 1.5 Sources of Information about Catalysis j13

Today, as catalysis is used and explored so depatisnet.dpma.de. It is possible to intensively by industry, much of the recently choose between a Beginners search acquired information is not available in and an Expert search, or to search for open access literature, but rather may be patent families. When using the located (at least in part) in patents. None- Assisted search, it is possible to forward theless, research details included in patents requests to the German patent may be obtained from various patent data- information system. bases, that include: . The patent database of the USA is . Espacenet: This is a European network administered by the United States of patent databases, which can be Patent and Trademark Office, and is accessed on the internet at www. linked under http://patft.uspto.gov. espacenet.com. It includes more than . Other important web addresses for patent 50 million patents from all around the databases include: world, which are frequently updated. . http://www.wipo.int/pctdb/en/index.jsp A quick search can include keywords, . http://pericles.ipaustralia.gov.au/ols/ inventors or companies; in an advanced auspat search, the various search terms can be . http://www.getthepatent.com linked together. For first-time visitors An . http://www.google.com/patents introduction to the database of ideas is . http://www.freepatentsonline.com/ provided on the portal site. search.html . Depatisnet: This is the database of the . http://www.ipo.gov.uk/types/patent.htm German Patent and Trade Mark Office . http://www.irossco.com/ (DPMA). It can be found at http:// patentsearching.htm

Take-Home Messages . Catalysts increase the rate at which a biocatalysis; and transition metal chemical system reaches its catalysis. equilibrium. . Homogeneous transition metal catalysts . In theory, catalysts are not consumed are characterized by high activities and during catalytic reactions; in reality, they high selectivities. Transition metal can be either destroyed or poisoned. catalysts can be adapted to the synthetic . Catalytic processes are usually demands by changing their ligand ﬁeld. presented in catalytic cycles. . Homogeneous transition metal . Catalysts can be divided into catalysts have advantages over the homogeneous and heterogeneous heterogeneous catalysts, because of catalysts. Homogeneous catalysts can be their well-known molecular dissolved in the reaction solvent; structure and their reproducible heterogeneous catalysts form a second, synthesis. As homogeneous catalysts usually solid, phase. are completely soluble, all metal . Homogeneous catalysis can be atoms can be catalytically active. There further subdivided into: acid/ are no diffusion problems involved in base catalysis; enzyme or homogeneous catalysis. 14j 1 Definition, Options, and Examples

. At ﬁrst glance, the demanding . Homogeneous transition metal separability appears to be a catalysis requires only mild conditions, disadvantage of homogeneous catalysis. and often allows the selective synthesis However, numerous possible of a desired product in a few reaction steps, approaches are available to resolve this without creating byproducts. Hence, it is a problem. cornerstone of green chemistry.

Exercise Questions 1.1 Which catalyst did Dobereiner€ use in his gas lighter? 1.2 Draw a general catalyst cycle of the Knallgas reaction! 1.3 List ﬁve advantages of homogeneous catalysis in comparison to heterogeneous catalysis. 1.4 What is the main problem associated with homogeneous transition metal catalysis? 1.5 How can Wilkinsons complex be synthesized? 1.6 Which products can be obtained catalytically from synthesis gas? 1.7 Draw at least three cyclic butadiene oligomers. Note the correct position of the double bonds. What is their technical importance? 1.8 How can a homogeneous transition metal catalyst be varied relatively easily? 1.9 Why are there no diffusion problems in homogeneous catalysis? 1.10 Which principles of green chemistry are met by homogeneous transition metal catalysis?

Literature M. Beller, C. Bolm (eds). Transition Metals for Organic Synthesis, Wiley-VCH, 2nd J. F. Hartwig. Organotransition Metal edition, 2004. A good reference book for Chemistry: From Bonding to Catalysis, organic chemists. University Science Books, 2010. P. W. N. M. van Leeuwen. Homogeneous A. Behr. Catalysis, Homogeneous, Ullmanns Catalysis – Understanding the Art, Kluwer Encyclopedia of Industrial Chemistry, Academic Publishing, 2004. Wiley-VCH, Weinheim, online edition, T. Horvath. Encyclopedia of Catalysis, Wiley- 2010. VCH, 6 Volumes, 2003. R. H. Crabtree (ed.): in: Handbook of Green B. Cornils, W. A. Herrmann, R. Schlogl,€ C.- Catalysis (ed.: P. T. Anastas), Vol. 1, H. Wong (eds). Catalysis from A to Z – A Homogeneous Catalysis, Wiley-VCH, Concise Encyclopedia, Wiley-VCH, 2nd Weinheim, 2009. edition, 2003. D. Steinborn. Grundlagen der metallorga- B. Cornils, W.A. Herrmann (eds). Applied nischen Komplexkatalyse [in German] Homogeneous Catalysis with Organome- Teubner, Wiesbaden, 1.Edition, tallic Compounds, Wiley-VCH, 2nd edi- 2007. tion, 2002. Three volumes; a good Literature j15

handbook for homogeneous transition Book series Topics in Organometallic metal catalysis; a third edition is in Chemistry, Springer-Verlag, Berlin, Hei- preparation. delberg, 37 volumes, up to 2011. Various J. Tsuji. Transition Metal Reagents and topics of homogeneous catalysis. Catalysis – Innovations in Organic Syn- Book series Catalysis by Metal Complexes, thesis, John Wiley & Sons, 2000. P. W. N. M. van Leeuwen, B. R. James S. Bhaduri, D. Mukesh. Homogeneous (eds), Springer-Verlag, Berlin, Heidel- Catalysis – Mechanisms and Industrial berg, 37 volumes (1976–2011). Books on Applications, Wiley-Interscience, New theoretical and practical aspects of York, 2000. homogeneous catalysis.