page_title: Sulfonic acid
section_title: Lignosulfonates
hierarchical_section_title: Sulfonic acid / Applications / Lignosulfonates
caption_attribution_description: English: idealized scheme for lignin depolymerization by sulfite process
context_page_description: A sulfonic acid refers to a member of the class of organosulfur compounds with the general formula R−S(=O)₂−OH, where R is an organic alkyl or aryl group and the S(=O)₂ group a sulfonyl hydroxide. As a substituent, it is known as a sulfo group. A sulfonic acid can be thought of as sulfuric acid with one hydroxyl group replaced by an organic substituent. The parent compound is the parent sulfonic acid, HS(=O)₂, a tautomer of sulfurous acid, S(OH)₂. Salts or esters of sulfonic acids are called sulfonates.
context_section_description: In the sulfite process for paper-making, lignin is removed from the lignocellulose by treating wood chips with solutions of sulfite and bisulfite ions.  These reagents cleave the bonds between the cellulose and lignin components and especially within  the lignin itself.  The lignin is converted to lignosulfonates, useful ionomers, which are soluble and can be separated from the cellulose fibers.
caption: idealized scheme for lignin depolymerization by the Sulfite process.
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