Pedro J. Pérez

Universidad de Huelva

Toward Sustainable Chemistry:

METhodologies for HEterogenising HOmogenous CATalysts

(METHEHOCAT)

Sustainable chemistry

Safer reactions

Catalysis

Renewable materials

Waste decrease

Energy efficiency

Minimize solvents

Atomic Selectivity

Non-toxic reagents

Sustainable chemistry

C

C-RC-P

R P

Catalysis

Chemical process:

Reactants (R) Products (P)

But…

-Many reactions are slow

-Many reactions give more than one product

A catalyst (C) is a compound that

increases the reaction rate (faster

processes) and provides the product we

look for, avoiding other non-desired

products (selectivity).

It works one time after another in the

so-called catalytic cycle.

Homogeneous and heterogeneous catalysis

ReactantsCatalystSolvent

The catalysis is homogeneous if the catalyst is dissolved in the same phase

than reactants.

f iltrationproducts

catalyst

ReactantsSolvent

The catalysis is heterogeneous if the

catalyst is not dissolved in the same phase

than reactants, and usually can be easily

separated at the end of the process,

allowing its recycling.

Goal #1: heterogenize the homogenous

We have already described homogenous

catalysts for several transformations.

The main goal of this joint project is to

develop heterogeneous catalysts based in

the anchoring technique, in which the

homogeneous catalysts will be fixed onto the

solid surface. Such fixation will be performed

in such a way that the metal centre will

behave identically to the homogeneous

counterpart.

zeolite

SBA-15 (silica)

MCF (silica)

N

N

R1

R3

B

H

R2 N

N

R1

R3

R2

N

N

R1

R3

R2N

N

R1

R3

C

H

R2 N

N

R1

R3

R2

N

N

R1

R3

R2

N

N

R1

R3

R2 N

N

R1

R3

R2

N

N

R1

R3

R2

N

Strategy and workplan

1) Preparation of catalyst precursors at UHU 2) Fixation onto solid supports at UALG

3) Catalytic tests and catalyst

recycling studies at UHU

+X

X

X = "CR2" or "NR"catalyst

+X

4) Data analysis and re-design

for optimization (UHU-UALG)

Goal #2: improving selectivity

The catalyst developed at UHU are based in pyrazolyl rings:

N

N

R1

R3

B

H

R2 N

N

R1

R3

R2

N

N

R1

R3

R2N

N

R1

R3

C

H

R2 N

N

R1

R3

R2

N

N

R1

R3

R2 N

N

R1

R3

R2 N

N

R1

R3

R2

N

N

R1

R3

R2

N

In order to improve the selectivity (enantioselectivity) in several transformations, it would be useful to

prepare new molecules containing pyrazoles containing stereocenters (a chiral atom). This

constitutes the second goal of this project, that will serve to develop mor selective catalysts for

certain transformations.

N

N

R1

R3

R2

H

*N

N

R1

R3

R2 N

N

R1

R3

R2

N

N

R1

R3

R2

X

* **

Strategy and workplan

1) Preparation of chiral pyrazoles at UALG 2) Preparation of catalyst precursors at UHU

3) Catalytic tests at UHU

N

N

R1

R3

R2

H

N

N

R1

R3

R2 N

N

R1

R3

R2

N

N

R1

R3

R2

X

* **

4) Data analysis and re-design

for optimization (UHU-UALG)

Preliminary results

N

N

R1

R3

C

H

R2 N

N

R1

R3

R2

N

N

R1

R3

R2N

N

R1

R3

B

H

R2 N

N

R1

R3

R2

N

N

R1

R3

R2N

N

R1

R3

R2 N

N

R1

R3

R2

N

N

R1

R3

R2

N

Goal #1: Catalyst precursors already prepared at UHU.

If X=SH it may be supported onto a Au film

N

N

R1

R3

C

O

R2 N

N

R1

R3

R2

N

N

R1

R3

R2

SiO O

R

SOLID SUPPORT

N

N

R1

R3

C

H

X N

N

R1

R3

R2

N

N

R1

R3

R2SiO

OO

Au

FILM

NN

Me3CO2CO

Cl

NH2NHCO2CMe3N

Cl

NHCO2CMe3

éter

65%

CH2Cl2

Na2CO3 +N

CO2Et CO2Et

CO2Et

N N

CO2CMe3

NH

CO2Et

32%

Preliminary results

O ONaHRCO2Et O

OR

1

2 a b

R = Ph (66%)R = CF3 (31%)

DMEreflux

NH2NH2

EtOH, reflux N

NH

R

N

NH

R

O

OR

R = Ph: CF3; Me

O

(R) - Camphor

3 a (~ 50%) from 1

N

NH

3 b (~18%) from 1

F3C

N

NH

Preliminary results

Preliminary results

NN

RX

NN

R

NNR

R= Ph; CF3

N

N

R1

R3

R2 N

N

R1

R3

R2

N

N

R1

R3

R2

X

* **

Strategy

Another approach , much interesting and innovative will be the design and preparation with the stereocentre on the metal (“active site”)

N

N

R1

R3

R2 N

N

R1

R3

R2

N

N

R1

R3

R2

X

* **

N

N

R1

R3

R2 N

N

R9

R7

R8

N

N

R5

R4

R6

X*

n

HN

N

HN

N

R1

R2

Strategy

N

N

N

N

R1R2n

B

N

N

R

H

Tl

N

N

N

N

R1R2n

B

N

N

R

H

Cu

L

Preliminary results

N

HN

HN

N

X

N

HN

HN

N

R2

R1

Possible types of spacer

2.8 A

NN

N

NN

BH

N

N

N

N

N

BH

3.1

Pyrazol position of connection with the spacer: strain for coordination

CO2Et

NC

MeS

SMe

R1

O

+ KOH

DMFOR1

SMe

CN

O

R1= a) 35%

b)

C6H5

(C6H4)-Me-p 39%

H2NNH2

NH

NR1

N

a) 72%b) 78%

DIBAL

NH

N

NH2

HN

N

HN

N

NH

R1R2

N

NH

R1

X

N

NH

R2

NH2

+

N

NH

R2

X

N

NH

R1

NH2

+

ERA Chemistry

Homogeneous Catalysis Laboratory