Cellulose Sulfuric Acid Catalysed Organic Synthesis; Starch Sulfuric Acid Catalysed Organic Synthesis; Xanthane Sulfuric Acid Catalysed Organic Synthesis; PEG-SO3H Catalysed Organic Synthesis; Silica Sulfuric Acid Catalysed Organic Synthesis; Alumina Sulfuric Acid Catalysed Organic Synthesis; Tungstate Sulfuric Acid Catalysed Organic Synthesis; Molybdate Sulfuric Acid Catalysed Organic Synthesis; Sulfated Zirconia Catalysed Organic Synthesis; SBA-Pr-SO3H Catalysed Organic Synthesis; MCM-41-SO3H Catalysed Organic Synthesis; Silica-Bonded S-Sulfonic Acid (SBSSA) Catalysed Organic Synthesis.