Propene isotopically labelled

Since at -40 °C the hexene polymerisation is living, the addition of 10 equivalents of propene to species 66 led to the complete consumption of propene and formation of a Zr-PP-fo-PH block (without further conversion of any unreacted Zr-Me precursor). The identification of the Zr-(propene)j.-(hexene)j, polymer was confirmed by isotopic labelling (l- C-propene, l,T-D-2,3- C-propene) and H,... 

The structure and properties of the initial nickel atom-propene complex has received detailed attention by Skell. The use of isotopically labeled propenes demonstrated that exchange occurs between the 1- and 3-positions but not between either the 1- and 2- or 2- and 3-positions (10) ... 

Isotopic labelling experiments have demonstrated that for the reaction of propene on MoC VTiC h or on photoreduced Mo03/TiC>2 the chain carrier for the degenerate metathesis is [Mo]=CHMe rather than [Mo]=CH2149-151. As a general rule in olefin metathesis a substituted carbene is less reactive than an unsubstituted carbene, and so the former tends to build up to a higher steady state. 

A number of classical studies were performed in the 1960s in which isotopically labelled propenes were fed to CU2O or bismuth molybdate catalysts. One series... 

Isotopic labelling studies (see Ch. 5) have shown that with terminal olefins nonproductive metathesis is generally much faster than productive metathesis. Reaction (4) at one time foimd practical application in the petrochemical industry as a means of converting surplus propene into useful products. Reactions of the higher alkenes provide routes to sex pheremones of insects. 

The proof that the C=C bond was itself being broken in these reactions was provided by isotopic labelling studies, first by Calderon in 1967 for the exchange reaction of but-2-ene [7,8], eq. (2), then by Boelhouwer (1968) for the reaction of propene [9], eq.(3), and later by DallAsta in 1971 for the ring-opening copolymerization of [1- C]cyclopentene with unlabelled cyclooctene [10]. 

Original scheme of hydrocarbon pool mechanism. Adapted from Dahl IM, Kolboe S. On the reaction mechanism for propene formation in the MTO reaction over SAPO-34. Catal Lett 1993 20 329-36 Dahl IM, Kolboe S. On the reaction mechanism for hydrocarbon formation from methanol over SAPO-34 1. Isotopic labeling studies of the co reaction ofethene and methanol. J Catal 1994 149 458—64. 

R0nning PO, Mikkelsen 0, Kolboe S. Effect of co-feeding ethene or propene on the conversion of methanol over H-ZSM-5. Use of isotopic labeling for mechanistic studies. In Proceedings of the 12th international zeolite conference. 2 1998. p. 1057. 

Example The transfer of a D compared to the transfer of an H during propene loss from partially labeled phenylproylethers is accompanied by an isotope effect, the approximate magnitude of which was estimated as follows [74]... 

As a means of obtaining additional information on the methanol to hydrocarbons reaction over zeohtes we have investigated the reaction between C labeled methanol and ( C) ethene or propene (made in situ from ethanol or isopropanol) over SAPO-34, H-ZSM-5, and dealumlnated mordenlte. The isotopic composition of the reaction products was measured by GC-MS. 

Nevertheless intramolecular proton shifts are competive with deprotonation under these conditions. The hydrocarbon products from the nitrous acid deamination of 1 -propylamine (628) consist of 10% cyclopropane and 90% propene. The 1-propanol (630) obtained from labeled (628) arises mainly by solvolytic displacement leading to isotopically unrearranged (630a) and partly from protonated cyclopropane with isotopic scrambling466. ... 

Syntheses of iabeiled cumenes were carried out by benzene aikyiation with propene in the adsorbed phase over H-ZSM-11. To avoid propene oligomerization, benzene was aiways adsorbed first. To synthesize cumene iabeiled with isotope in the a-position of the aikyl chain (cumene 1), non-labelled benzene and propene 2- 3C were used. Cumene - labelled in the p-positions of the alkyl chain (cumene 2) was synthesized from non-labelled benzene and propene l- C. Cumene with 13C isotopes in p- positions of the alkyl chain and in the aromatic ring (cumene 3) was synthesized from all-ring labelled benzene (5% and a mixture of unlabelled propene and propene l- C (1 1). 

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