Process for production of vitamin a

Process for the production of a compound of formula (formula (I)

• wherein
• R is H or
• and wherein R1 is a linear or branched C1-C18 alkyl moiety, characterized in that in a first step (step (i))
• the compound of formula (II)
• is reacted with a compound of formula (III)
• wherein R (and also R1) has the same meanings as defined for the compound of formula (I), and then in a second step (step (ii))
• the reaction product of step (i), which is the compound of formula (IV)
• wherein R (and also R1) has the same meanings as defined for the compound of formula (I), is converted into the compound of formula (I) by heating the reaction mixture.