Acidic elimination for bio-based aromatics

A process for the preparation of an aromatic product according to formula IIIa or IIIb, said process comprising a step a) of contacting a cycloadduct according to formula I with an acidic mixture comprising a first acid and an activating agent to obtain one or more intermediate compounds, which is followed by a step b) of adding a further acid to the one or more intermediate compounds, which further acid is more of the first acid and/or an additional acid with respect to the first acid of step a) to form the aromatic product according to formula IIIa or IIIb, wherein the one or more intermediate compounds in step b) are present in a mixture including part of the acidic mixture,

• wherein,
• R1 and R2 are independently selected from the group consisting of H, C1-C20 alkyl, CH2OH and esters and ethers thereof, CO2H and esters thereof;
• R3 and R4 are independently selected from the group consisting of H, CH3, CH2OH and esters and ethers thereof, CO2H and esters thereof, amides and tertiary amines of CH2NH2, and an electron-withdrawing group,
• or R3 and R4 together represent —(CO)X(CO)—, wherein X═O, CH2, NH, NMe, NEt, NPr, NBu, NPh, or S;
• or R2 and R4 together represent —CH2ZC(O)—, wherein Z is selected from the group consisting of O, NH and S;
• and
• represents a single or double bond,
• wherein the first acid and the further acid each individually comprises an acid selected from the group consisting of organic acids, dry inorganic acids and solid acids;
• wherein the first acid and cycloadduct are contacted in a molar range of 2:1 to 0.01:1;
• wherein the activating agent is selected from the group consisting of acylating agents, triflating agents, sulfonating agents, carbamylating agents, carbonylating agents, and combinations thereof;
• wherein the activating agent and cycloadduct are contacted in a molar range of 30:1 to 1:1;
• wherein the amount of further acid that is contacted with the one or more intermediate compound(s) is at least 0.25 molar equivalents based on the starting amount of the cycloadduct;
• and
• wherein step a) is carried out at a temperature in the range of −20 to 60° C. and wherein step b) is carried out below 150° C.