Silica Gel-Supported Polyphosphoric Acid (PPA/SiO2): An Efficient and Reusable Heterogeneous Catalyst for Facile Synthesis of 14-Aryl-14H-dibenzo[a,j]xanthenes under Solvent-free Conditions

2011 ◽  
Vol 29 (2) ◽  
pp. 297-302 ◽  
Author(s):  
Amir Khojastehnezhad ◽  
Abolghasem Davoodnia ◽  
Mehdi Bakavoli ◽  
Niloofar Tavakoli-Hoseini ◽  
Mohsen Zeinali-Dastmalbaf
Keyword(s):  
Heterogeneous Catalyst ◽  
Silica Gel ◽  
Polyphosphoric Acid ◽  
Solvent Free ◽  
Facile Synthesis ◽  
Solvent Free Conditions

Catalytic acetylation of (+)-cedrol with heterogeneous catalyst H2SO4/SiO2 under solvent free conditions

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Acetic Anhydride ◽  
Heterogeneous Catalyst ◽  
Silica Gel ◽  
Solvent Free ◽  
Molar Ratio ◽  
Optimum Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solvent Free Conditions ◽  
Bet Method

Heterogeneous catalyst, H2SO4/SiO2 was synthesized by immobilizing sulfuric acid on silica gel as solid support. Silica gel was prepared from kaolin, originating from Belitung island Indonesia. The synthesized catalyst was characterized by various techniques such as X-ray diffraction, scanning electron microscopy, Fourier transform Infrared spectroscopy and BET method and was applied for the acetylation of (+)-cedrol compound using acetic anhydride under solvent free conditions. The optimum conditions for catalytic acetylation were found at 353 K for 20 h reaction period, the molar ratio (+)-cedrol/acetic anhydride 1:10 in the presence of 5%-w of catalyst converted 88,7% (+)-cedrol into cedryl acetate. Results revealed catalyst could possibly be used for cedryl acetate synthesis from (+)-cedrol.

Efficient thioacetalisation of carbonyl compounds

2014 ◽  
Vol 68 (3) ◽  
Author(s):  
Davood Habibi ◽  
Payam Rahmani ◽  
Ziba Akbaripanah
Keyword(s):  
Reaction Time ◽  
Heterogeneous Catalyst ◽  
Sulphuric Acid ◽  
Silica Gel ◽  
Carbonyl Compounds ◽  
Solvent Free ◽  
Short Reaction Time ◽  
Solvent Free Conditions ◽  
Derivatives Of ◽  
Efficient Heterogeneous Catalyst

AbstractThe thioacetalisation of a variety of heterocyclic, aromatic, and aliphatic carbonyl compounds (1 mmol) with ethane-1,2-dithiol (1 mmol) using silica sulphuric acid (SSA) is presented as an efficient heterogeneous catalyst under mild and solvent-free conditions at 60°C. The thioacetals were formed within a short reaction time (1–34 min) and isolated with 90–98 % yield following an extractive procedure and chromatography on silica gel. The competitive protection reaction between aldehyde and ketone with ethane-1,2-dithiol afforded the protected derivatives of benzaldehyde and acetophenone with 92 % and 8 % yields, respectively, indicating some selectivity.

Silica Gel Supported Sodium Hydrogen Sulfate as an Efficient and Reusable Heterogeneous Catalyst for the Synthesis of Imines in Solvent-free Conditions under Microwave Irradiation

2005 ◽  
Vol 2005 (5) ◽  
pp. 299-303 ◽  
Author(s):  
Mannathusamy Gopalakrishnan ◽  
Purushothaman Sureshkumar ◽  
Vijayakumar Kanagarajan ◽  
Jeyaraman Thanusu ◽  
Ramalingam Govindaraju
Keyword(s):  
Microwave Irradiation ◽  
Heterogeneous Catalyst ◽  
Silica Gel ◽  
Diethyl Ether ◽  
Carbonyl Compounds ◽  
Solvent Free ◽  
Hydrogen Sulfate ◽  
Sodium Hydrogen ◽  
Solvent Free Conditions

This synthesis of imines has been carried out efficiently by the condensation of carbonyl compounds with amines in the presence of silica gel supported sodium hydrogen sulfate (NaHSO4.SiO2) as a heterogeneous catalyst under microwave irradiation in solvent-free conditions. NaHSO4.SiO2 can be recovered and re-used up to ten times by simple washing with diethyl ether after each use and activated in an oven at 120 °C for 1 h, thus rendering the process more economical.

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