Use of metal-accumulating plants for implementing chemical reactions

1. A composition comprising at least one metal catalyst of a metal in the M(II) form, the metal being selected from the group consisting of zinc (Zn), nickel (Ni), manganese (Mn), lead (Pb), and cadmium (Cd),

said metal originating from a calcined plant or calcined plant part, and

said composition having been acid treated,

wherein the composition catalyzes organic synthesis reactions involving said catalyst.

2. The composition according to claim 1 , wherein the acid treatment is carried out by hydrochloric acid.

3. The composition according to claim 1 , wherein the acid treated composition is subsequently filtered.

4. The composition according to claim 1 , wherein said plant is from the Brassicaceae family.

5. The composition according to claim 1 , wherein said plant is Anthyllis vulneraria, Thlaspi caerulescens , or Arabidopsis hallerii , and the metal is Zn.

6. The composition according to claim 5 , wherein the Zn concentration in the plant is from 2700 mg/kg to 43700 mg/kg of dry weight of plant or plant part.

7. The composition according to claim 1 , wherein said composition further comprises at least one of Fe(III) and Al(III).

8. The composition according to claim 1 , wherein said plant belongs to the Sapotaceae family, and the metal is Ni.

9. The composition according to claim 8 , wherein the Ni concentration in the plant is from 1000 mg/kg to 36000 mg/kg of dry weight of plant or plant part.

10. The composition according to claim 3 , wherein the composition comprises zinc and/or iron(III), the composition further being purified by an ion exchange resin, liquid-liquid extraction with trioctylamine, selective precipitation, or liquid/solid extraction by washing with acetone.

11. The composition according to claim 3 , wherein the composition comprises iron present in M(III) form in a proportion less than 2% by weight with respect to the concentration of zinc, the composition further being purified by liquid-liquid extraction with versatic acid or (2-ethylhexyl) phosphoric acid, or reduction with sodium sulphite.

12. The composition according to claim 1 , wherein the composition is devoid of or contains only traces of chlorophyll.

13. A composition comprising at least one metal catalyst of a metal in the M(II) form,

said metal being selected from the group consisting of zinc (Zn), nickel (Ni), manganese (Mn), lead (Pb), and cadmium (Cd),

said metal originating from a calcined plant or calcined plant part, and

said composition having been acid treated and filtered and being devoid of or containing only traces of chlorophyll,

wherein the composition catalyzes organic synthesis reactions involving said catalyst.

14. The composition according to claim 13 , wherein said metal is Zn or Ni.

15. The composition according to claim 1 , wherein said plant is Psychotria douarrei and the metal is Ni.

16. The composition according to claim 1 , wherein said plant is chosen from the genus Geissois or the genus Alyssum , and the metal is Ni.