Silica Sulfuric Acid and Related Solid-supported Catalysts as Versatile Materials for Greener Organic Synthesis

Nano-ZrO2 sulfuric acid: a heterogeneous solid acid nano catalyst for Biginelli reaction under solvent free conditions

“…In addition, transport pathways of reactants and products in the nanomaterial-based catalysts could be signicantly shortened unlike many heterogeneous support matrices where a great portion of catalyst sites are present deep inside the matrix backbones and reactants have only limited access to the catalytic sites. 15,16 Sulfonation with chlorosulfonic acid 17,18 is an efficient procedure for heterogenization of homogeneous catalysts that has been much attention aer Zolgol's report on the preparation of silica sulfuric acid. 19 Zirconia (ZrO 2 ) is one of the most important ceramic materials that are widely used in chemical industry due to their unique electrical, mechanical, optical and thermal properties.…”

Nanostructured silicate catalysts for environmentally benign Strecker-type reactions:status quoandquo vadis

“…However, pure SiO 2 is not active in the S-3-CR, as indicated by Iwanami et al, 32 while silica sulfuric acid (SSA, SiO 2 -SO 3 H) is very effective, as demonstrated by Chen and Lu. 46 This reusable green and inexpensive heterogeneous acid catalyst has been widely investigated [47][48][49][50][51] since 2001, when Zol-gol described its preparation by using a simple reaction of neat chlorosulfonic acid and silica gel (Fig. 2A).…”

A greatly improved procedure for the synthesis of an antibiotic-drug candidate 2,4-diacetylphloroglucinol over silica sulphuric acid catalyst: multivariate optimisation and environmental assessment protocol comparison by metrics

“…30,31 Besides, heterogeneous catalysis in the solvent-free condition is considered as a green and sustainable approach since the elimination of solvents and reduces the environmental factor (E-factor). To this endeavour, we developed a novel catalyst system for the synthesis of DAPG, namely, silica sulphuric acid or H 2 SO 4 -SiO 2 (SSA), which was invented by Zolgol, 32 obtained from silica gel (SG) and supported by sulphuric acid, 33 which was used for the rst time in promoting the synthesis of disulphide and thionitrites under mild conditions. This catalyst system provided various benets, including increase in the surface area, improved thermal and mechanical stabilities, as well as simplicity of handling and reusability.…”