Hydration of aromatic terminal alkynes catalyzed by iron(III) sulfate hydrate under chlorine-free conditions

Iron Catalysis in Organic Synthesis

“…852 Working in acetic acid at 95°C, several example substrates could be converted to aryl methyl ketones. Diethynylarenes could be converted to the monoacetyl or the diacetyl derivatives depending on the structure of the substrate.…”

Iron(III)‐Catalyzed Hydration of Unactivated Internal Alkynes in Weak Acidic Medium, under Lewis Acid‐Assisted Brønsted Acid Catalysis

“…The conditions (95°C) which had allowed for near quantitative formation of acetophenone from phenylacetylene (2 a) left a significant amount of unreacted 1-phenylpropyne. [21] Regarding the higher conversion of these alkylarylalkynes vs 1-phenylpropyne, it is worth mentioning that an increase of yield at increasing length of the alkyl chain of PhC � CR (R = Me, Et, Bu) was also found under catalysis of FeCl 3 / 3·AgNTf 2 . Elution by column chromatography gave pure 3 in 61% yield.…”

“…[21] ðAcOHÞFe 3þ ðH 2 OÞ x þ H 2 O ) * The low coordinating ability and basicity of the sulfate ions may assist both coordination of AcOH as well as protonic release.…”

“…Following from those seminal works based on stoichiometric [16] or catalytic FeCl 3 , [17] the extension to few cases of internal alkynes was achieved in presence of FeCl 3 /3·AgNTf 2 in dioxane/H 2 O, [18] or of FeCl 2 ·4H 2 O/methanesulfonic acid in 1,2-dichloroethane (DCE). [21] In this case acetic acid serves as the proton donor and the iron salt, in the form of easily handable whitish crystals, is the cocatalyst. [20] We have shown that iron III sulfate hydrate added to glacial acetic acid promotes the hydration of terminal alkynes.…”

Solvent-free hydration of alkynes over Hβ zeolite

“…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]. Whereas, most of these metal catalysts have shortcomings, such as lower reactivity, recovery and reuse of (expensive) catalysts and prohibit their frequent use for laboratory as well as industrial purpose.…”