Papers by David Cole-Hamilton
Dalton Transactions, 2018
In memory of Roberto Sánchez-Delgado a good scientist and great friend. In the reaction of [RuHCl... more In memory of Roberto Sánchez-Delgado a good scientist and great friend. In the reaction of [RuHClP3] (P = PPh3) with NaOMe in methanol, the product is [RuH2(CO)P3]. Short reaction times show that the final product is formed through [RuH4P3] as the major intermediate. Using NaOCD3 in CD3OD, the first formed product is [RuH4P'3] (P' is PPh3 partially deuterated in the ortho positions of the aromatic rings). Further reaction leads to a mixture of [RuHnD2-n(CO)P3] (n = 0, 22 %; n = 1, 2 isomers each 28 %; n = 2, 22 %). Mechanistic aspects of both steps of the reaction are explored and, together with previously published calculations, they provide definitive mechanisms for both dehydrogenation and decarbonylation in these interesting systems.
Green Chemistry, 2017
A new and selective route for the synthesis of polymer precursors, primary diamines or N-substitu... more A new and selective route for the synthesis of polymer precursors, primary diamines or N-substituted diamines, from dicarboxylic acids, diesters, diamides and diols using a Ru/ triphos catalyst is reported. Excellent conversions and yields are obtained under optimised reaction conditions. The reactions worked very well using 1,4-dioxane as solvent, but the greener solvent, 2-methyl tetrahydrofuran, also gave very similar results. This method provides a potential route to converting waste biomass to value added materials. The reaction is proposed to go through both amide and aldehyde pathways.
Chemical Reviews, May 7, 2021
The bidentate phosphine ligand 1,2-bis(di-tert-butylphosphinomethyl)benzene (1,2-DTBPMB) has been... more The bidentate phosphine ligand 1,2-bis(di-tert-butylphosphinomethyl)benzene (1,2-DTBPMB) has been reported over the years for being one, if not the, best ligand for achieving the alkoxycarbonylation of various unsaturated compounds. Bonded to palladium, the ligand provides the basis for the first (Alpha) step in the commercial production of methyl methacrylate as well as very high selectivity to linear esters and acids from terminal or internal double bonds. The present review is an overview covering the literature dealing with the 1,2-DTBPMB ligand: from its first reference, its catalysis, including the alkoxycarbonylation reaction and its mechanism, its isomerization abilities, including the highly selective isomerizing methoxycarbonylation, other reactions such as cross-coupling, recycling approaches and the development of improved, modified ligands, in which some tert-butyl ligands are replaced by 2-pyridyl moieties and which show exceptional rates for carbonylation reactions at low temperatures. Cone angle 276°9 [Pt-complex] Names CAS 121954-50-5 Related to o-xylene backbone α,α'-bis(di-tert-butylphosphino)-o-xylene (DTBPX, Bupox) Related to benzene backbone 1,2-bis(di-tert-butylphosphinomethyl)benzene (DTBPMB, DTPB) Table 2: most encountered catalyzed carbonylation reactions Reaction References Function built Scheme Alkoxycarbonylation of alkenes section 2 and 3 Saturated ester
Chemistry: A European Journal, Sep 5, 2014
A detailed mechanism for alkyne alkoxycarbonylation mediated by a palladium catalyst has been cha... more A detailed mechanism for alkyne alkoxycarbonylation mediated by a palladium catalyst has been characterised in detail at the B3PW91-D3/PCM level of density functional theory (including bulk solvation and dispersion corrections). This transformation, investigated via the methoxycarbonylation of propyne, involves a uniquely dual role for the P,N hemilabile ligand acting co-catalytically as both an in-situ base and proton relay coupled with a Pd(0) centre, allowing for surmountable barriers (highest ∆G ‡ of 22.9 kcal/mol for alcoholysis). This proton-shuffle between methanol and coordinated propyne accounts for experimental requirements (high acid concentration) and reproduces observed regioselectivities as a function of ligand structure. A simple ligand modification is proposed, which is predicted to improve catalytic turnover by three orders of magnitude.
Chemcatchem, Aug 19, 2013
Green Chemistry, 2012
Dimethyl I, 19-no nadecanedioate is produced from the methoxycarbonylation of commercial olive, r... more Dimethyl I, 19-no nadecanedioate is produced from the methoxycarbonylation of commercial olive, rapeseed or sunflower oils in the presence of a catalyst derived from [Pd 2 (dba)3], bis(ditertiarybutylphosphinomethyl)benzene (BDTBPMB) a nd methanesulphonic acid (MSA). The diester is then hydrogenated to I, 19-nonadecanediol using Rul I, I, I-tris-(diphenylphosphinemethyl)ethane (triphos). I, 19-Nonadecadienoic acid is hydrogenated to short chain oligoesters, which ca n themselves be hydrogenated to I, 19-nonadecanol by hyd rogenation in the presence of water.
Dalton Transactions, 2015
The utilisation of the PNP iridium pincer complex [Ir(PNP)(COE)][BF 4 ] [PNP = 2,6-bis{(di-tertbu... more The utilisation of the PNP iridium pincer complex [Ir(PNP)(COE)][BF 4 ] [PNP = 2,6-bis{(di-tertbutylphosphino)methyl}pyridine; COE = cyclooctene] in the sp 3 C-H activation of methyl propanoate and other related esters was explored. In particular, this study provides further insight into the factors that govern the regioselectivity of such reactions. These included factors such as the steric demands of the substrate, the formation of favourable ring systems as well as the electronic effects that may influence the 65
Journal of Organometallic Chemistry, Apr 1, 2004
Triaryl-phosphines and-phosphites bearing fluorous ponytails give high rates, good linear selecti... more Triaryl-phosphines and-phosphites bearing fluorous ponytails give high rates, good linear selectivity and good retention of catalyst in the fluorous phase during hydroformylation of alkenes in fluorous solvents.
Chemie in unserer Zeit
, the UK voted by a small majority to leave the european Union. The campaign had created major di... more , the UK voted by a small majority to leave the european Union. The campaign had created major divisions within UK society and the aftermath has sadly enhanced these divisions with entrenched positions being taken up on both sides of the argument. Curiously, in this context, even the most vociferous proponents of leaving the eU understand that research, innovation and education are areas where the UK has benefitted enormously from its membership of the eU and involvement in the Framework programmes including horizon 2020. W riting in The Scotsman following the publication of the Royal Society of edinburgh's Advice paper to the UK negotiators, Sir John elvidge (Chair of the Strategy Group) and i (Chair of the SubGroup for Research, innovation and Tertiary education) concluded: "the best way to…(develop UK research) ... is for the UK to remain fully in h2020 and the developing european Research Area, including shaping the projects and planning future programmes."
Green Chemistry, 2014
Starting from a purified cashew nut shell extract containing mostly anacardic acid derivatives, t... more Starting from a purified cashew nut shell extract containing mostly anacardic acid derivatives, the tsetse fly attractants 3-ethyl-and 3-propylphenol were selectively synthesised. The mixture was first converted into 3-(non-8-enyl)phenol in 98% purity via ethenolysis and distillation with concomitant decarboxylation. The olefinic side chain was then shortened by isomerising cross-metathesis with short-chain olefins in the presence of a [Pd(µ-Br)(t Bu 3 P)] 2 isomerisation catalyst and a second-generation Hoveyda-Grubbs catalyst, and the synthesis was completed by a hydrogenation step.
Journal of the Chemical Society, 1991
Chapter 1 Hydrocarboxylation of alkenes and polvbutadienes Background and literature review RCH=C... more Chapter 1 Hydrocarboxylation of alkenes and polvbutadienes Background and literature review RCH=CH2 R-CH-CH2 V II o [1] R-CH-CH2 o R-CH-CH3 (a) COOH (a-methyl carboxylic acid) R-CH2CH2COOH (b) (n-cai'boxylic acid) Scheme 1.1 Depending on the amount of catalyst used (Reppe normally used the nickel com plex [Ni(C0)4 ]), distinctions were made between a stoichiometric (Equation 1.4), and a catalytic conversion (Equation 1.5). Stoichiometric 4CH-CH2 + Ni(CO)4 + 4C2H5OH + 2HC1
Organometallics, Jan 7, 2015
The catalytic alkoxycarbonylation of alkynes via palladium and P,N ligands, studied through a pro... more The catalytic alkoxycarbonylation of alkynes via palladium and P,N ligands, studied through a prototypical reaction involving propyne methoxycarbonylation yielding methyl methacrylate, has been explored at the B3PW91-D3/PCM level of density functional theory. Four different reaction routes have been probed in detail, spanning those involving one or two hemilabile P,N ligands and either hydride or carbomethoxy mechanisms. The cycle that is both energetically most plausible and congruent with experimental data involves Pd(0) and two P,N ligands acting co-catalytically in turn to shuffle protons via both protonation and deprotonation reactions. Other mechanisms proposed in the literature can be discounted because they would lead to insurmountable barriers or incorrect selectivities. For the preferred mechanism, the P,N ligand is found to be crucial in determining the strong regioselectivity and intrinsically controls the overall turnover of the catalytic cycle with moderate barriers (∆G ‡ of 20.1 to 22.9 kcal/mol) predicted. Furthermore, the necessary acidic conditions are rationalized via a potential dicationic channel.
RSC Sustainability
Agrochemicals help feed the world. Ammonia production uses huge amounts of methane and energy whi... more Agrochemicals help feed the world. Ammonia production uses huge amounts of methane and energy whilst contributing 1.8% of CO2. Green hydrogen would alleviate these problems whilst directed delivery could eliminate run off and eutrophication.
Chemistry – A European Journal, 2020
Chemistry International, 2019
We used to chant a rhyme when we were young (I had three dominant sisters and no brothers!): “Wha... more We used to chant a rhyme when we were young (I had three dominant sisters and no brothers!): “What are little girls made of? Sugar and spice and all things nice. What are little boys made of? Slugs and snails and puppy dog’s tails.” The truth is, of course, that they are all made from the same things, as is everything around them that makes up our diverse and beautiful world as well as much of the universe—the 90 natural elements that are the building blocks of life. It is an amazing thought that these are only building blocks so it is essential that we should nurture and cherish all of them if we are to continue to enjoy life in its abundance.
Chemistry - A European Journal, 2018
Employment conditions and career opportunities are in the focus of the new Employment Survey for ... more Employment conditions and career opportunities are in the focus of the new Employment Survey for European Chemists (ESEC2). Conditions and opportunities are individually analysed for all countries with a statistically significant number of responses. The results provide important clues for careers in these countries and in Europe as a whole. The importance of employer sectors varies very much between European countries. A chapter of this report is devoted to career planning of students and new graduates. This is the first general evaluation of the survey. It provides many details about the chemistry workforce in Europe and its development.
Le Journal de Physique IV, 1991
AbsSract-ZnSe has been grown by atmospheric pressure metal-organic chemical vapour deposition (AP... more AbsSract-ZnSe has been grown by atmospheric pressure metal-organic chemical vapour deposition (APMOCVD) using DEZn and H, Se (5% in H,). The preparation and purification of DEZn
Dalton Transactions, 2003
Chemical Reviews, 2021
The bidentate phosphine ligand 1,2-bis(di-tert-butylphosphinomethyl)benzene (1,2-DTBPMB) has been... more The bidentate phosphine ligand 1,2-bis(di-tert-butylphosphinomethyl)benzene (1,2-DTBPMB) has been reported over the years for being one, if not the, best ligand for achieving the alkoxycarbonylation of various unsaturated compounds. Bonded to palladium, the ligand provides the basis for the first (Alpha) step in the commercial production of methyl methacrylate as well as very high selectivity to linear esters and acids from terminal or internal double bonds. The present review is an overview covering the literature dealing with the 1,2-DTBPMB ligand: from its first reference, its catalysis, including the alkoxycarbonylation reaction and its mechanism, its isomerization abilities, including the highly selective isomerizing methoxycarbonylation, other reactions such as cross-coupling, recycling approaches and the development of improved, modified ligands, in which some tert-butyl ligands are replaced by 2-pyridyl moieties and which show exceptional rates for carbonylation reactions at low temperatures. Cone angle 276°9 [Pt-complex] Names CAS 121954-50-5 Related to o-xylene backbone α,α'-bis(di-tert-butylphosphino)-o-xylene (DTBPX, Bupox) Related to benzene backbone 1,2-bis(di-tert-butylphosphinomethyl)benzene (DTBPMB, DTPB) Table 2: most encountered catalyzed carbonylation reactions Reaction References Function built Scheme Alkoxycarbonylation of alkenes section 2 and 3 Saturated ester
Uploads
Papers by David Cole-Hamilton