Kinetics of catalytic Meerwein-Ponndorf-Verley reduction of aldehydes and ketones using boron triethoxide

2010 ◽  
Vol 64 (1) ◽  
Author(s):  
Burcu Uysal ◽  
Birsen Buyuktas
Keyword(s):  
Room Temperature ◽  
Aromatic Aldehydes ◽  
Reduction Reaction ◽  
Aliphatic Aldehydes ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Kinetics Of ◽  
Membered Transition State ◽  
Mpv Reduction ◽  
Respective Rate

AbstractCatalytic Meerwein-Ponndorf-Verley (MPV) reduction of various aliphatic, aromatic, and unsaturated aldehydes and ketones to corresponding alcohols (analyzed by GC-MS) in the presence of boron triethoxide (B(OEt)3) were studied. Kinetics of this reduction reaction was also studied and the respective rate constants were determined. It was found that B(OEt)3 catalyzes the reduction of aliphatic aldehydes and ketones to alcohols at room temperature while aromatic aldehydes and ketones were not reduced under the same conditions. In addition, MPV reduction using B(OEt)3 was found to be chemoselective as unsaturated aldehydes and ketones afforded the corresponding alcohols without affecting unsaturated groups. The mechanism proposed involves a six-membered transition state in which both the alcohol and the carbonyl are coordinated to the same boron centre of a boron alkoxide catalyst.

ChemInform Abstract: L-Proline-Catalyzed the Synthesis of Aromatic Aldehydes and Ketones and Their Acridione Derivatives at Room Temperature.

ChemInform ◽  
2016 ◽  
Vol 47 (6) ◽  
pp. no-no
Author(s):  
Fang-Ming Wang ◽  
Dan Bao ◽  
Bing-Xiang Hu ◽  
Ze-Yu Zhou ◽  
Deng-Deng Huang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Aromatic Aldehydes ◽  
Aldehydes And Ketones

Decarboxylative Umpolung Synthesis of Amines from Carbonyl Compounds

Synlett ◽  
2020 ◽  
Vol 31 (16) ◽  
pp. 1543-1550
Author(s):  
Baoguo Zhao ◽  
Wen-Wen Chen
Keyword(s):  
Carbonyl Compounds ◽  
Aromatic Aldehydes ◽  
High Reactivity ◽  
Mild Conditions ◽  
Intramolecular Reaction ◽  
Unsaturated Aldehydes ◽  
Recent Advances ◽  
Intermolecular Reaction ◽  
Aldehydes And Ketones

2-Azaallyl anions are valuable intermediates which have versatile applications in functionalization with various electrophiles. Decarboxylation of the imines formed from aromatic aldehydes and α,α-diphenylglycine provides an interesting and efficient way to generate delocalized 2-azaallyl anions, which display high reactivity toward different electrophiles with excellent regioselectivity at the diphenylketimino aryl carbon of the 2-azaallyl anions. The transformation produces various amines in good yields under very mild conditions. This Synpacts article highlights the recent advances on the decarboxylative umpolung synthesis of amines from carbonyl compounds.1 Introduction2 Decarboxylative Umpolung Reactions of Carbonyl Compounds with Different Electrophiles2.1 Reaction with π-Allyl–Pd(II) Species2.2 Reaction with Morita–Baylis–Hillman Adducts2.3 Reaction with Imines2.3.1 Intermolecular Reaction with N-Ts Imines2.3.2 Intramolecular Reaction with Chiral N-tert-Butanesulfinyl Imines2.4 Reaction with Aldehydes and Ketones3 Decarboxylative Umpolung Reaction of α,β-Unsaturated Aldehydes with Aldehydes4 Conclusion

NaBH4/NaHSO4·H2O a Heterogeneous Acidic System for a Mild and Convenient Reduction of Carbonyl Compounds under Protic Condition

2005 ◽  
Vol 60 (4) ◽  
pp. 453-457 ◽  
Author(s):  
Behzad Zeynizadeh ◽  
Tarifeh Behyar
Keyword(s):  
Carbonyl Compounds ◽  
Room Temperature ◽  
Reduction Reactions ◽  
Heterogeneous Condition ◽  
Unsaturated Aldehydes ◽  
Sodium Bisulfate ◽  
Aldehydes And Ketones ◽  
Acidic Reagent

NaBH4 in the presence of sodium bisulfate (NaHSO4·H2O), a weakly acidic reagent, efficiently reduces a variety of carbonyl compounds such as aldehydes, ketones, α,β -unsaturated aldehydes and ketones, α-diketones and acyloins to their corresponding alcohols in acetonitrile under heterogeneous condition. Reduction reactions were accomplished at room temperature or under reflux condition

scholarly journals Regioselective and Chemoselective Reduction of α,β-Unsaturated Carbonyl Compounds by NaBH4/Ba(OAc)2 as a Reducing System

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Mina Mohamadi ◽  
Davood Setamdideh ◽  
Behrooz Khezri
Keyword(s):  
Carbonyl Compounds ◽  
Room Temperature ◽  
Allylic Alcohols ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones

α,β-unsaturated aldehydes and ketones are regioselectively reduced to the corresponding allylic alcohols with NaBH4/Ba(OAc)2 system in CH3CN. This system is also efficient for the chemoselective reduction of enals in the presence of enones at room temperature.

l-Proline-Catalysed the Synthesis of Aromatic Aldehydes and Ketones and their Acridione Derivatives at Room Temperature

2015 ◽  
Vol 39 (8) ◽  
pp. 445-450 ◽  
Author(s):  
Fang-Ming Wang ◽  
Dan Bao ◽  
Bing-Xiang Hu ◽  
Ze-Yu Zhou ◽  
Deng-Deng Huang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Aromatic Aldehydes ◽  
Aldehydes And Ketones

Investigation of irradiation-induced nucleation processes in silicon and germanium

1995 ◽  
Vol 53 ◽  
pp. 224-225
Author(s):  
Harry A. Atwater ◽  
C.M. Yang ◽  
K.V. Shcheglov
Keyword(s):  
Room Temperature ◽  
Crystal Size ◽  
Initial Distribution ◽  
Engineering Control ◽  
Size Evolution ◽  
Silicon And Germanium ◽  
Ge Quantum Dot ◽  
And Control ◽  
Germanium Quantum Dots ◽  
Kinetics Of

Studies of the initial stages of nucleation of silicon and germanium have yielded insights that point the way to achievement of engineering control over crystal size evolution at the nanometer scale. In addition to their importance in understanding fundamental issues in nucleation, these studies are relevant to efforts to (i) control the size distributions of silicon and germanium “quantum dots𠇍, which will in turn enable control of the optical properties of these materials, (ii) and control the kinetics of crystallization of amorphous silicon and germanium films on amorphous insulating substrates so as to, e.g., produce crystalline grains of essentially arbitrary size.Ge quantum dot nanocrystals with average sizes between 2 nm and 9 nm were formed by room temperature ion implantation into SiO2, followed by precipitation during thermal anneals at temperatures between 30°C and 1200°C[1]. Surprisingly, it was found that Ge nanocrystal nucleation occurs at room temperature as shown in Fig. 1, and that subsequent microstructural evolution occurred via coarsening of the initial distribution.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

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