Solve this ‘wordoku’ in the same way as a sudoku with letters instead of numbers (the nine letters once in each row, column and nine-square cell). Once solved, one of the overall diagonals contains the jumbled surname of a French chemist who gave his name to a rearrangement reaction. At the time of his death in 1945 he was president of the French Chemical Society.

This week’s letters are: A E F I M N S T U