Efficient production of high value added materials via selective hydroformylation of difficult substrates like internal alkenes and butadiene.

醛是制备多种精细化学品和散装化学品的重要中间体。这些化合物的应用被发现在制药工业，芳香和香料工业，并在生产农用化学品和洗涤剂。目前，这些产品中的许多都是通过化学计量反应制备的，这往往会产生大量的化学废物。人们越来越需要基于温和的选择性反应和非常高的原子效率的新生产方法，从而减少化学废物问题。铑催化烯烃的氢甲酰化就是这样一个温和而清洁的生产高质量醛的过程的例子，只使用CO和H2作为试剂，因此根本不产生废物。在这个项目中，我们将开发一种新的普遍适用的催化剂体系，能够将内烯烃和共轭二烯转化为高附加值的醛和/或酯。原子经济、清洁的丁二烯氢甲酰化合成中间体1,6-己二醛技术将为聚酰胺的可持续生产做出重大贡献。然而，许多工业和学术研究人员已经研究了铑催化的丁二烯氢甲酰化反应，但通常报道的期望产物1,6-己二醛的选择性很低。这是由有害的Rh烯丙基和烯酸酯络合物的形成引起的，可以通过使用适当设计的双金属催化剂同时激活两种烯烃功能来抑制。因此，我们将开发定义良好的四膦配体系统，用于形成双金属配合物，能够通过两种金属与官能团的相互作用激活否则不活泼的底物。起点将是一种成功的双齿配体，已经由PI开发出来，它将被修饰成这样一种方式，即它们可以通过与双酸的缩合直接桥接。由此产生的四膦将提供新的双金属配合物，将应用于共轭二烯的氢甲酰化。在后期阶段，新的配体体系将在不同的反应中进行探索，如钯催化的二烯烷氧羰基化。精确的配体结构可以通过空间、电子和咬角性质的细微变化来优化。在另一种方法中，我们将着眼于两种不同配体骨架的耦合，这开辟了形成杂双金属配合物的可能性。配体主链结构的不同会对不同过渡金属的络合常数产生影响。预计这可以用来影响一种过渡金属对另一种过渡金属的优先配位。将研究这是否会导致选择性地形成基于铑和钯的杂双金属配合物，而不受同金属双核化合物的干扰。我们将探索这些铑钯杂双金属配合物作为二烯一锅氢甲酰化/甲氧羰基化催化剂的使用。通过两步工艺形成这些α， ω -醛酯已被DSM/杜邦深入研究。新的手性催化剂的设计将得到在实际反应条件下存在的催化物种的基本光谱（包括动力学）研究的支持。HP-NMR将用于研究静态条件下双金属配合物的结构。研究了金属-金属距离对与双功能底物相互作用的影响。HP-IR将用于在实际催化条件下研究这些配合物。

Aldehydes are important intermediates for the preparation of a large variety of fine- and bulk-chemicals. Applications of these compounds are found in the pharmaceutical industry, aroma and flavour industry, and in the production of agrochemicals and detergents. Many of these products are currently prepared via stoichiometric reactions which often results in large amounts of chemical waste. There is an increasing demand for new production methods based on mild and selective reactions with a very high atom efficiency , thus reducing the chemical waste problem. The rhodium catalysed hydroformylation of alkenes is an example of such a mild and clean process for the production of high-quality aldehydes, using only CO and H2 as reagents and therefore producing no waste products at all.In this project we will develop a new generally applicable catalyst system capable of converting both internal alkenes and conjugated dienes into high value-added aldehydes and / or esters. Atom economic and clean hydroformylation technology of butadiene to the intermediate 1,6-hexanedial would create a major contribution to the sustainable production of polyamides. Many industries and academic researchers, however, have studied the rhodium-catalyzed hydroformylation of butadiene, but generally the reported selectivity for the desired product 1,6-hexanedial is very low. This is caused by the formation of deleterious Rh allyl and enolate complexes, which can be suppressed by simultaneous activation of both alkene functions using properly designed bimetallic catalysts.Therefore, we will develop well-defined tetraphosphine ligand systems for the formation of bimetallic complexes capable of activating otherwise unreactive substrates by mutual interactions with functional groups by both metals. Starting point will be a successful class of bidentate ligands, already developed by the PI, which will be modified in such a way that they can be bridged straightforwardly by condensation with diacids. The resulting tetraphosphines will provide novel bimetallic complexes that will be applied in the hydroformylation of conjugated dienes. In a later stage the novel ligands systems will be explored in different reactions like palladium catalyzed alkoxycarbonylation of dienes. The exact ligand structures can be optimized by subtle changes in steric, electronic and bite-angle properties. In another approach we will aim at coupling of two different ligand backbones which opens the possibility of the formation of heterobimetallic complexes. Differences in the structure of the ligand backbone will have impact on the complexation constants of different transition metals. It is anticipated that this can be employed to influence the preferential coordination of one transition metal over another. It will be investigated if this will lead to the selective formation of heterobimetallic complexes based on rhodium and palladium without interference of homometallic binuclear compounds. We will explore the use of these rhodium palladium heterobimetallic complexes as catalyst for one-pot hydroformylation / methoxycarbonylation of dienes. The formation of these alpha,omega-aldehyde esters via a two-step process has been investigated intensively by DSM/DuPont.The design of the new chiral catalysts will be supported by fundamental spectroscopic (including kinetic) studies of the catalytic species present under actual reaction conditions. HP-NMR will be used to study the structure of the bimetallic complexes under static conditions. The effect of the metal-metal distance on the interaction with bifunctional substrates will be investigated. HP-IR will be used to study these complexes under actual catalytic conditions.