Alkylcyclopentane ring

The alkylcyclopentane (AGP) to aromatics process (ACP ACH Ar) is less efficient than ACH dehydrogenation, owing to the slowness of the first step and to ACP ring opening. Under conditions where cyclohexane is converted to benzene with close to 100% efficiency, only 50—75% of methylcyclopentane may be converted to benzene. 

Alkylcyclopentanes and cyclohexanes rearrange to aliphatic alkenes during both photolysis and radiolysis [108-113]. The double bond in the product aliphatic alkenes can be found connected to one of the carbon atoms taking part in ring opening. The derivation of... 

From this compound as well as from other alkylcyclohexanes the yield of ring-opening products is relatively small, about = 0.1-0.4, and G = 0.3-1.6 [108,110] (Table 6), while usually the main decomposition process is the hydrogen formation, which leaves the cyclic structure intact. Here, and with the other alkylcyclohexanes and alkylcyclopentanes, the scission of the ring to smaller molecular mass alkenes and cyclopropane derivates was detected with very low yield. 

Il in and Usov have shown that over acidic platinum-alumina catalyst there are at least two consecutive pathways from n-nonane to indan (57) either through alkylaromatic intermediates, by first closing the six-membered ring or through alkylcyclopentane intermediates, by first closing a five-membered ring (Table VII and Fig. 6). 

The ring-opening reaction of methylcyclopentane (Scheme 3) is the reverse reaction of the dehydrocyclization of methylpentanes (Scheme 2). Reactions of alkylcyclopentanes on supported and unsupported transition metal catalysts are also very important in naphtha reforming processes . ... 

On the other hand, the application of Pt black or Pt/Si02 as catalyst for the hydro-genolysis of the alkylcyclopentanes 1-5 leads mainly to ring-opened products and alkylcyclopentene formation, whereas aromatization is not significant. The product distribution is strongly dependent on the hydrogen gas pressure. ... 

Ring extension and dehydrogenation of alkylcyclopentanes to benzene derivatives,... 

Two types of reactions were observed with alkylcyclopentanes. A nonse-lective ring opening would cleave each C—C bond (in positions a, b, and c. Fig. 3) in a random way. This was reported for Pt/Al203 with high dispersion (7). A selective splitting, on larger Pt particles, would break di-secondary C—C bonds (6 and c) only (7,20). The splitting close to the tertiary (or quaternary) C atom is hindered to different extent over various metals in most cases, but the total inactivity of this bond is rare (8). A third, partially selective mechanism (7) was also considered, but its possible mechanism was not elucidated sufficiently. 

Adducts from 1,2-bis(trimethylsilyloxy)cyclopentene and acetals rearrange in acidic solution to give 3-alkylcyclopentane-l,2-diones (Scheme 42). This behaviour is paralleled in the six-membered-ring series, but contrasts with the sequence starting with the cyclobutene, which ring-expands to give 2-alkylcyclo-pentane-1,3-diones. 

Similarly to alkanes, cycloalkanes can also undergo catalytic transformations in the presence of bimetallic catalysts. For instance, decalin (D) is transformed into a mixture of its skeletal isomers, ring-opening products (ROPs), ie, Cio-alkylcyclohexanes and CiQ-alkylcyclopentanes, and CPs, ie, hydrocarbons having fewer than 10 carbon atoms in the molecule, on acidic zeolites. The transformation of decalin on zeolites is of consecutive nature isomers are the primary products and are converted in the course of reaction further into ROPs, which ultimately yield CPs (Fig. 8.10). 

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