Gas-phase Meerwein–Ponndorf–Verley reaction: correlation of the 3665 cm−1 IR band with the cis-alcohol selectivity

Akata, Burcu; Warzywoda, Juliusz; Sacco, Albert

doi:10.1016/j.jcat.2003.11.008

Cited by 16 publications

(3 citation statements)

References 26 publications

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“…In the recent decades acidic aluminosilicate zeolites have been used to catalyse many reactions important from the industrial point of view such as cracking, isomerization, alkylation and dehydration because of their high activity and selectivity [1][2][3][4][5][6][7][8][9][10][11][12]. The catalytic activity of acidic zeolites is related to the proton present with tetrahedral Al(III) atom in the framework of silica with Si(IV) atom to compensate negative charge of aluminosilicate zeolite structure.…”

Section: Introductionmentioning

confidence: 99%

Preparation of two series of VxSiBeta zeolite catalysts with V centres in framework and extra-framework positions and their application in selective oxidation of methanol

Trejda

Millot

Chałupka

et al. 2019

Applied Catalysis A: General

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A B S T R A C TTwo series of V-containing Beta zeolites have been prepared by contacting of the aqueous NH 4 VO 3 solution with two SiBeta zeolites at pH = 2.5 and 6, respectively. Because of the presence in NH 4 VO 3 solution at pH = 2.5 mainly monomeric VO 2 + ions, vanadium have been easily incorporated into framework of SiBeta zeolite as pseudo-tetrahedral non hydroxylated (SiO) 3 V = O and hydroxylated (SiO) 2 (OH)V = O species. The moderate nucleophilicity of the basic vanadyl oxygen of the latter species play important role in methanol oxidation toward formaldehyde. The selectivity toward formaldehyde on this series of V x SiBeta(I) increases with the amount of pseudo-tetrahedral hydroxylated (SiO) 2 (HO)V = O species, which act as either redox or acidic and basic centres. In contrast at pH = 6, the aqueous NH 4 VO 3 solution is expected to contain both mononuclear and polynuclear V ions, thus it is more difficult to incorporate V species in SiBeta at this condition as shown by FT-IR and NMR data. The absence of pseudo-tetrahedral V species in framework position of V 0.6 SiBeta(II) is probably responsible for lack of activity of this catalyst in methanol oxidation. The appearance of this species in the series of V x SiBeta(II) zeolites for high V content leads to their activity in methanol oxidation toward formaldehyde.

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Section: Introductionmentioning

confidence: 99%

Preparation of two series of VxSiBeta zeolite catalysts with V centres in framework and extra-framework positions and their application in selective oxidation of methanol

Trejda

Millot

Chałupka

et al. 2019

Applied Catalysis A: General

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“…In addition to serving as spectroscopic models of partially hydrolyzed framework sites, complexes 10 and 11 were investigated as functional models of reactivity.P artially hydrolyzed framework sites of group-13 metalsh ave been proposed as precatalysts for MPV transfer hydrogenation of ketones and al-dehydes using alcohols as sacrificial reductants. [17,19,[102][103][104] It has been established that isolated group-13 alkoxide surface speciesa re active for MPV transfer-hydrogenation catalysis; however,t he structures and mechanismsf or generation of such surface sites are debated. [23,105] The isolation of 10 and 11, which mimic defective framework sites that have been partially hydrolyzed, provides an opportunity to investigate proposed precatalyst initiation steps starting from aH OM[OSiO 3 ] 3 partially hydrolyzed surface site.…”

Section: Vibrational Spectroscopic Analysis Of Complexes 6 7 10 11mentioning

confidence: 99%

“…However, the chemistry described above provides am odel of the behavior of isolated defect site structures ands upportst he assertion that partially hydrolyzed sites can readily generate alkoxides upon exposure to alcohols, an ecessary step in proposed mechanisms for MPV active site formation. [7,8,15,17,19,25,[102][103][104][108][109][110][111][112][113][114][115]…”

Section: Vibrational Spectroscopic Analysis Of Complexes 6 7 10 11mentioning

confidence: 99%

Siloxyaluminate and Siloxygallate Complexes as Models for Framework and Partially Hydrolyzed Framework Sites in Zeolites and Zeotypes

Dombrowski

Ziegler

Phadke

et al. 2020

Chemistry A European J

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Anionic molecularm odels for nonhydrolyzed and partially hydrolyzeda luminum and gallium framework sites on silica, M[OSi(OtBu) 3 ] 4 À and HOM[OSi(OtBu) 3 ] 3 À (whereM= Al or Ga), were synthesized from anionic chlorides Li{M[O-Si(OtBu) 3 ] 3 Cl} in salt metathesisr eactions. Sequestration of lithium cationsw ith[ 12]crown-4a fforded charge-separated ion pairs composed of monomeric anionsM [OSi(OtBu) 3 ] 4 À with outer-sphere [([12]crown-4) 2 Li] + cations, and hydroxides {HOM[OSi(OtBu) 3 ] 3 }w ith pendant [([12]crown-4)Li] + cations. These molecular modelsw ere characterized by single-crystal X-ray diffraction, vibrational spectroscopy,m ass spectrometry and NMR spectroscopy.U pon treatment of monomeric [([12]crown-4)Li]{HOM[OSi(OtBu) 3 ] 3 }c omplexes with benzyl alcohol, benzyloxide complexes were formed, modeling a possible pathway for the formation of actives ites forM eerwin-Ponndorf-Verley (MPV) transfer hydrogenations with Al/ Ga-doped silica catalysts.

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Meerwein‐Ponndorf‐Verley Reduction

2010

Comprehensive Organic Name Reactions and Reagents

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It is an aluminum alkoxide‐catalyzed reduction of carbonyl compounds (ketones and aldehydes) to corresponding alcohols using another alcohol (e.g., isopropanol) as the reducing agent or hydride source. This reaction is generally referred to as the Meerwein–Ponndorf–Verley reduction (MPV) or Meerwein–Ponndorf–Verley reaction. Later several improvements have been incorporated for this reaction. This reaction has various advantages and does not affect other double bonds or triple bonds as well as other enolizable carbonyl compounds. All the steps of the reaction and suitable catalyst have been discussed. The study finds that the yields of reduction can be further enhanced by using freshly prepared nonaggregated aluminum alkoxide or by a slow addition of carbonyl compounds into the aluminum alkoxide solution, in addition, this reaction has been modified to reduce carbonyl compounds enantioselectively.

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Gas-phase Meerwein–Ponndorf–Verley reaction: correlation of the 3665 cm−1 IR band with the cis-alcohol selectivity

Cited by 16 publications

References 26 publications

Preparation of two series of VxSiBeta zeolite catalysts with V centres in framework and extra-framework positions and their application in selective oxidation of methanol

Preparation of two series of VxSiBeta zeolite catalysts with V centres in framework and extra-framework positions and their application in selective oxidation of methanol

Siloxyaluminate and Siloxygallate Complexes as Models for Framework and Partially Hydrolyzed Framework Sites in Zeolites and Zeotypes

Meerwein‐Ponndorf‐Verley Reduction

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