Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-03-01
2002-09-17
Lambkin, Deborah C. (Department: 1626)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S282000, C556S009000, C556S013000, C556S012000, C556S011000
Reexamination Certificate
active
06451937
ABSTRACT:
1. FIELD OF THE INVENTION
The field of the invention pertains to the selective functionalizing of a hydrocarbon at its primary C—H site by thermally reacting a functionalizing reagent and the hydrocarbon in the presence of an transition metal catalyst.
2. BACKGROUND OF THE INVENTION
Aliphatic compounds, and especially alkanes, are among the most abundant but least reactive molecules. Chemical synthesis relies on reactions that form one product selectively, and few reactions involving aliphatic compounds such as alkanes occur in this fashion. Radical reactions, such as halogenations and autoxidations, typically produce mixtures of products; even enzymes do not react regiospecifically with linear alkanes. Transition metal compounds are known to react with alkanes to give terminal alkyl complexes selectively, but these reactions are typically stoichiometric in metal. Transition metal-catalyzed dehydrogenation suffers from unfavorable thermodynamics and isomerization of terminal to internal alkenes during the reaction. Carbonylation of alkanes is also endothermic, and the photochemical processes produce secondary photoproducts.
Several years ago, it was reported in K. M. Waltz; C. N. Muhoro, J. F. Hartwig, Organometallics, 1999, 21 and in K. Waltz, J. F. Hartwig, Science 1997, 277, 211, that low valent transition metal complexes containing boryl ligands reacted with hydrocarbons, including alkanes, by photochemical dissociation of ligand to produce functionalized hydrocarbons. It was reported that organoboronate esters were formed in a stoichiometric fashion by the regiospecific replacement of one hydrogen on a terminal position with a boryl group. It was also reported in H.Chen, J. F. Hartwig, Angew.Chem.Int.Ed.Engl 1999 that commercially available R
2
BBR
2
(R
2
=pinacolate) reagents and substituted cyclopentadienyl (Cp*) Re(CO)
3
would catalytically convert alkanes to alkylboronate esters under photochemical reaction conditions. Photochemical processes, however, are impractical at an industrial scale.
It is desirable to functionalize regiospecifically an aliphatic compounds at its terminal C—H site. It is also desirable that the process for the functionalization occur thermally rather than through other means such as photochemical processes. It is also an object of the invention to manufacture a functionalized aliphatic compounds, and especially a functionalized alkane, by a process which is catalytic rather than stoichiometric in metal.
3. SUMMARY OF THE INVENTION
There is now provided a process for the catalytic coupling of aliphatic hydrocarbons with certain reagents under thermal conditions to selectively functionalize the aliphatic hydrocarbon at its terminal C—H site.
In one embodiment, there is provided a process for selectively functionalizing an aliphatic or alkyl branched alicyclic hydrocarbon at a primary C—H hydrocarbon bond comprising thermally reacting a functionalizing reagent and the hydrocarbon in the presence of a catalyst, said catalyst comprising:
a) a source of a transition metal;
b) a source of a 3 to 8, cyclic or non-cyclic, aromatic or non-aromatic, neutral, cationic or anionic, substituted or unsubstituted electron donor moiety which does not dissociate under thermal reaction conditions, wherein said moiety
(i) lacks aromatic C—H bonds on the moiety directly bonded to the transition metal, or
(ii) contains sterically hindered aromatic C—H bonds on the moiety directly bonded to the transition metal; and
c) a source of ligands capable of formally donating an electron pair to the transition metal a) and which dissociate thermally;
and wherein said functionalizing reagent comprises a source of boron.
In another embodiment, there is provided a catalytic process having more than 50 turnovers comprising thermally activating said catalyst in the presence of a functionalizing reagent and an alipahtic or alkyl branched alicyclic hydrocarbon containing primary C—H bonds, said catalyst comprising:
a) a source of a transition metal;
b) a source of a 3 to 8, cyclic or non-cyclic, aromatic or non-aromatic, neutral, cationic or anionic, substituted or unsubstituted electron donor moiety which does not dissociate under thermal reaction conditions, wherein said moiety
(i) lacks aromatic C—H bonds on the moiety directly bonded to the transition metal, or
(ii) contains sterically hindered aromatic C—H bonds on the moiety directly bonded to the transition metal; and
c) a source of ligands capable of formally donating an electron pair to the transition metal a) and which dissociate thermally;
and wherein said functionalizing reagent comprises a source of B, C, N, O, Si, P, S, Ge, As, Al, or Se.
In yet another embodiment of the invention, there is provided a functionalization process comprising selectively functionalizing 80% or more of primary C—H hydrocarbon bonds in a hydrocarbon composition in the presence of a thermally activated catalyst, wherein said process turns over the catalyst 50 or more times.
Preferably, the catalyst composition used in the process of the invention is comprised of, or obtained by combining a source of the following in any sequence:
a) a source of a transition metal;
b) a source of a 3 to 8, cyclic or non-cyclic, aromatic or non-aromatic, neutral, cationic or anionic, substituted or unsubstituted electron donor moiety which does not dissociate under thermal reaction conditions, wherein said moiety
(i) lacks aromatic C—H bonds on the moiety directly bonded to the transition metal, or
(ii) contains sterically hindered C—H bonds on the moiety directly bonded to the transition metal; and
c) a source of ligands comprising trialkylsilanes, unsaturated aliphatic compounds, &pgr; allyl compounds, or &pgr; arene compounds, wherein said &pgr; arene compounds
(i) lack aromatic C—H bonds on the moiety directly bonded to the transition metal, or
(ii) contain sterically hindered aromatic C—H bonds on the moiety directly bonded to the transition metal.
A more preferred catalyst used in the process of the invention comprises, or is obtained by combining a source of the following in any sequence:
a) Rh or Ir;
b) a fully substituted cyclic C
5
moiety having a &pgr;-coordinated electronic structure and lacking aromatic C—H bonds; and
c) ligands comprising aliphatic unsaturated or &pgr; arene compounds, and wherein said &pgr; arene compounds
(i) lack aromatic C—H bonds on the moiety directly bonded to the transition metal, or
(ii) contain sterically hindered aromatic C—H bonds on the moiety directly bonded to the transition metal.
There is further provided a functionalization process comprising selectively functionalizing 80% or more of primary C—H hydrocarbon bonds in a hydrocarbon composition in the presence of a thermally activated catalyst and a functionalizing reagent, wherein said functionalizing reagent comprises a compound containing a moiety represented by the following structure:
4. DETAILED DESCRIPTION OF THE INVENTION
The process of the invention is 80% or more selective toward functionalizing a primary C—H bond on hydrocarbon molecules, is catalytic, and relies ton thermal rather than photolytic or photochemical processes to supply the activation energy required for dissociating the ligand from the catalyst. The reaction proceeds in a straightforward manner in that a hydrocarbon, a catalyst, and a functionalizing reagent are contacted in a reaction vessel and heated to a temperature effective to activate the reaction towards the functionalization of the hydrocarbon at its primary C—H site. The nature of the catalyst and functionalizing reagent as described in further detail below enable one to manufacture selectively and thermally a hydrocarbon functionalized at its primary C—H site.
In the process of the invention, the hydrocarbon is functionalized at a terminal C—H bond in the presence of a catalyst and a functionalizing reagent. The catalyst used in the reaction must be one which is capable of being thermally activated, and the process functionalizes the terminal C—H bond of a hydrocarbon by thermally activating the catalyst. By thermal a
Chen Huiyuan
Hartwig John F.
Semple Thomas Carl
Lambkin Deborah C.
Shell Oil Company
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