Which of the following compounds do not undergo aldol condensation?

The carbonyl compounds which have alpha carbon undergoes the aldol condensation. Option (i) and (iii) have alpha hydrogen so they will undergo aldol condensation.

Option (ii) and (iv) will not undergo aldol condensation, as they do not have alpha hydrogen.

Thus, option (ii) and (iv) are the correct options.

Red color hydrogen is alpha hydrogen.