Specific dehydrogenation process (i)

Process for the production of the compounds of formula (II)

• wherein
• R is —CH═O or —COOR′, wherein R′ is a —C1-C16 alkyl group (preferably —CH3 or —CH2CH3 or —C15H31),
• by selective dehydrogenation of the compounds of formula (I)
• wherein
• R has the same meanings as in the compound of formula (II),
• wherein the dehydrogenation is carried out in the presence of at least one oxidative reactant of formula (III)
• wherein
• R1 is —CN, —Cl or —F,
• R2 is —CN, —Cl or —F,
• R3 is —H, —CH3, —Cl or —F, and
• R4 is —H, —CH3, —Cl or —F.