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I came across the following question:

Sucrose on treatment with conc. $\ce {HCl}$ produces? The answer is given as levulinic acid.

So how exactly does sucrose produce levulinic acid?

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The internet links provided in the Comments do not give much detail as to the stepwise mechanism for the transformation of fructose 1 to levulinic acid 12. I presume that you recognize that the sucrose acetal linkage is hydrolyzed in aqueous acid and that the resultant (+)-D-glucose and (-)-D-fructose are interconvertible via enolization of the carbonyl group. As a monomer, fructose 1 prefers the pyranose closed form over the furanose form 2. Facile loss of water from 2 forms cation 3 that, via the enol 4, affords aldehyde 5. Acid-catalyzed loss of two equivalents of water (steps not shown but straightforward) from 5 leads to 5-hydroxymethylfurfural (6). Cation 7 is formed and is hydrated to provide 8. Hydration of the formyl group forms 9 followed by loss of formic acid affording 2-hydroxy-5-methylfuran 10. 2-Hydroxyfurans readily tautomerize to the keto form, in this instance to the enol lactone 11. Hydrolysis of 11 affords levulinic acid 12. I presume that the name levulinic acid arises because it is derived from (-)-fructose, aka, levulose, a name derived from the sign of its optical rotation. You may want to compare the similarities of this mechanism with the one offered by user55119 here.

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