Catalytic Hydration of Alkylacetylenes¹

Solvent-free hydration of alkynes over Hβ zeolite

“…Ketones are unambiguously important motifs in modern organic synthesis. Mercury (II) salts combined with acids, such as HgO/H 2 SO 4 and HgO/BF 3 , are reliable catalysts for the hydration of alkynes and these catalysts were extensively used in high-scale industrial processes until the discovery of the toxicity of mercury salts [3,4]. Alternative metallic catalysts have been searched over the years, mainly transition metal based catalysts, such as Pt [5,6], Fe [7,8], Pd [9], Ir [10], Ag [11,12], Os [13] and Au [14,15].…”

Ruthenium piano-stool complexes bearing imidazole-based PN ligands

“…1 One of the longest known reactions to catalyze the hydration of alkynes is the reaction with mercury(II) salts. 2,3,4 Even though mercury is extremely hazardous, this reaction is still the favoured process for industrial application because it is reliable and produces good yields. 5 Other metal-based catalysts which catalyze the Markovnikov as well as anti-Markovnikov hydration include NaAuCl 4 , RuCl 3 and [Ru(III)(EDTA-H)Cl], RhCl 3 , PtCl 4 and the Zeise dimer [{PtCl 3 (CH 2 =CH 2 )} 2 ], just to name a few.…”

“…2,3,4 Even though mercury is extremely hazardous, this reaction is still the favoured process for industrial application because it is reliable and produces good yields. 5 Other metal-based catalysts which catalyze the Markovnikov as well as anti-Markovnikov hydration include NaAuCl 4 , RuCl 3 and [Ru(III)(EDTA-H)Cl], RhCl 3 , PtCl 4 and the Zeise dimer [{PtCl 3 (CH 2 =CH 2 )} 2 ], just to name a few. 6,7,8,9,10,11,12,13 Besides these homogenous catalysts also heterogenous catalyst systems are used.…”

“…17,18 The catalytic activity as well as the selectivity of ruthenium(II) depends on the nature of the phosphine ligands. 19 Using PPh 2 (C 6 F 5 ) and P(3-C 6 H 4 SO 3 Na) 3 as ligands leads to selective anti-Markovnikov addition of water and satisfactory yields of the aldehyde. However, these catalytic systems involve a high catalyst/metal loading and yield only moderate turnovers and selectivity.…”

“…20 Nature uses proteins as polyfunctional ligands, which show multiple interactions between the enzyme and either substrate, intermediate(s), or transition state(s) during the catalytic cycle. 3 For example, the tungsteno enzyme acetylene hydratase of Pelobacter acetylenicus uses acetylene as the sole carbon source, which is converted to acetaldehyde and then used by the enzyme to build acetic acid and…”