Sodium Hydrogen Sulfate: Safe and Efficient

Biographical Sketches

Eskandar Kolvari was born in Garmsar, Iran, in 1977. He received his B.Sc. in Applied Chemistry (2000) from Sharif University of Technology, Iran and his M.Sc. in Organic Chemistry (2003) from Bu-Ali Sina University, Hamadan, Iran. He is currently working towards his Ph.D. under the supervision of Professor Mohammad Ali Zolfigol at Bu-Ali Sina University. His research interests include the application of new catalysts in organic reactions.

Introduction

Although NaHSO₄ has been known for a long time, only in recent years it emerged as an efficient catalyst in or­ganic chemistry. The new interest in this salt is due to ­environmental and economical considerations that prompt urgent need to redesign important chemical processes ­using suitable catalysts. NaHSO₄ can be used alone or supported on alumina [1] or silica gel, in solvent or under solvent-free conditions. The most often used form of it is the silica gel supported form. This catalyst promotes ­various transformations like selective and regioselective protection and deprotection, [2-9] nitration, [10] nitrosation, [11] oxidation, [12] Beckman rearrangement, [1] synthesis of halide derivatives, [13] [14] coupling of indoles, [15] and synthesis of quinazolinones.¹⁶

The advantages of using NaHSO₄ include operational simplicity, selectivity, and availability, and it is inexpensive and ecologically friendly.

Abstracts

(A) Bis- and tris(1H-indol-3-yl)methanes are synthesized in high yields by an electrophilic substitution reaction of indoles with ­carbonyl compounds under mild reaction conditions using silica-supported NaHSO4 and Amberlyst-15. [15]
(B) Silica gel supported sodium hydrogen sulfate was found to be an efficient catalyst for the selective removal of the N-Boc protecting group from aromatic amines, keeping aliphatic N-Boc intact. [2]
(C) A combination of NaHSO4 and NaNO2 in the presence of wet SiO2 was used as an effective nitrosating agent for the nitrosation of secondary amines to their corresponding nitroso derivatives under mild conditions. [11]
(D) Different p-hydroxybenzyl alcohols were subjected to NaHSO4·SiO2 and it was shown that this catalyst can transform p-hydroxybenzyl alcohols to the corresponding p-hydroxybenzyl ethers and thioethers efficiently and selectively. [6]
(E) Cyclic and acyclic ketones, amides, and β-keto esters were converted to their α-brominated derivatives using NaHSO4·SiO2 in the presence of NBS and with Et2O or CCl4 as solvent at room temperature. [13]
(F) 1,2-Dihydroquinolines were subjected to oxidation effectively and in short reaction times with Na2Cr2O7·H2O and NaHSO4 as catalyst. The reactions proceed under mild conditions and with dichloromethane as solvent. [12b]
(G) The reaction of ethyl glyoxylate with different heteroaromatic compounds in the presence of sodium salts was investigated. It was shown that NaHSO4 is effective and affords Friedel-Crafts addition products in good yield under aqueous conditions. [17]

References

• 1 Gopalakrishnan M. Sureshkumar P. Kanagarajan V. Thanusu J. Lett. Org. Chem.  2005,  2:  444 
• 2 Ravindranath N. Ramesh C. Reddy M. Das B. Adv. Synth. Catal.  2003,  345:  1207 
• 3 Das B. Mahender G. Kumar V. Chowdhury N. Tetrahedron Lett.  2004,  45:  6709 
• 4 Ramesh C. Ravindranath N. Das B. J. Org. Chem.  2003,  68:  7101 
• 5 Ramesh C. Mahender G. Ravindranath N. Das B. Tetrahedron Lett.  2003,  44:  1465 
• 6 Ramu R. Nath N. Reddy M. Das B. Synth. Commun.  2004,  34:  3135 
• 7 Zhang Z. Monatsh. Chem.  2005,  136:  1191 
• 8 Mahender G. Ramu R. Ramesh C. Das B. Chem. Lett.  2003,  32:  734 
• 9 Breton GW. J. Org. Chem.  1997,  62:  8952 
• 10a Zolfigol MA. Madrakian E. Ghaemi E. Ind. J. Chem., Sect. B: Org. Chem. Incl. Med. Chem.  2001,  40:  1191 
• 10b Zolfigol MA. Madrakian E. Ghaemi E. Molecules  2001,  6:  614 
• 11 Zolfigol MA. Madrakian E. Ghaemi E. Kiani M. Synth. Comm.  2000,  11:  2057 
• 12a Shirini F. Zolfigol MA. Torabi S. Lett. Org. Chem.  2005,  2:  544 
• 12b Damavandi JA. Zolfigol MA. Karimi B. Synth. Commun.  2001,  31:  3183 
• 12c Zolfigol MA. Sadeghi MM. Mohammadpoor-Baltork I. Ghorbani Choghamarani A. Taqian-nasab A. Asian J. Chem.  2001,  13:  887 
• 13 Das B. Venkateswarlu K. Mahender G. Mahender L. Tetrahedron Lett.  2005,  46:  3041 
• 14 Das B. Banerjee J. Ravindranath N. Tetrahedron  2004,  60:  8357 
• 15 Ramesh C. Banerjee J. Pal R. Das B. Adv. Synth. Catal.  2003,  345:  557 
• 16 Das B. Banerjee J. Chem. Lett.  2004,  33:  960 
• 17 Zhuang W. Jorgensen KA. Chem. Commun.  2002,  1336