Synthesis of Bifunctional Monomers by the Palladium-Catalyzed Carbonylation of Cardanol and its Derivatives

• Published in: ChemCatChem Vol. 8; no. 4; pp. 751 - 757
• Main Authors: Mgaya, James E., Bartlett, Stuart A., Mubofu, Egid B., Mgani, Quintino A., Slawin, Alexandra M. Z., Pogorzelec, Peter J., Cole-Hamilton, David J.
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 18-02-2016; Wiley Subscription Services, Inc
• Subjects: lactones; oligomerization; palladium; Phenols; Polymerization; renewable resources
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.201501110

A 1,2‐bis(di‐tert‐butylphosphinomethyl)benzene‐modified palladium catalyst has been used to synthesize bifunctional monomers of different chain lengths from cardanol. Short‐chain derivatives of cardanol, such as (E)‐3‐(dodec‐8‐enyl)phenol; HOPhC12‐ene, (E)‐3‐(undec‐8‐enyl)phenol; HOPhC11‐ene, (E)‐3‐(dec‐8‐enyl)phenol; HOPhC10‐ene, and 3‐(non‐8‐enyl)phenol; HOPhC9‐ene, were synthesized by the metathesis of cardanol with symmetrical internal alkenes. These derivatives were methoxycarbonylated to produce monomers with different chain lengths such as methyl‐16‐(3‐hydroxyphenyl)hexadecanoate; HOPhC15COOMe, methyl‐13‐(3‐hydroxyphenyl)tridecanoate; HOPhC12COOMe, methyl‐12‐(3‐hydroxyphenyl)dodecanoate; HOPhC11COOMe, methyl‐11‐(3‐hydroxyphenyl)undecanoate; HOPhC10COOMe, and methyl‐10‐(3‐hydroxyphenyl)decanoate; HOPhC9COOMe, respectively. Polymerization of the synthesized monomers produced oligomers that consist of up to seven monomer units as confirmed by MALDI‐TOF‐MS. Lactone formation was also observed in some cases under polymerization conditions.
Catalysis goes nuts! Cardanol, derived from cashew nut shell liquid, and its short‐chain derivatives obtained by metathesis can be methoxycarbonylated into bifunctional ester phenols. The reaction with [Ti(OBu)4] then gives polymers or macrolactones.