US EPA

1177615 

Journal Article 

Reactivity of some C-8-alkenes in etherification with methanol 

Karinen, RS; Krause, AOI 

1999 

1 

Applied Catalysis A: General
ISSN: 0926-860X
EISSN: 1873-3875 

188 

1-2 

247-256 

10.1016/S0926-860X(99)00216-1 

WOS:000083466100022 

This work concerns the reactivity of some tertiary C-8-alkenes in the etherification reaction. 2,4,4-trimethyl-1-pentene, 2,4,4-trimethyl-2-pentene, 2-methyl-1-heptene and 2-methyl-2-heptene were chosen as the model compounds and their etherification with methanol was studied in the liquid phase at 50-90 degrees C using a commercial ion-exchange resin as a catalyst. The comparison was made with the reactivity of tertiary C-5-alkenes. The reactivity was observed to vary with each molecule: the longer the carbon chain, the slower the reaction rate. Apparent activation energies for the ether formation were determined from the initial reaction rates, being 60-65 kJ/mol for 2,4,4-trimethyl pentenes and 90 kJ/mol for 2-methyl-1-heptene. In addition to the etherification the double bond isomerisation was detected and also some isomerisation experiments without methanol were carried out. An interesting feature in the isomerisation between 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene was observed: the ratio of isomers settled at a Value which was independent of the temperature favouring the alpha-form and thus being far from the expected thermodynamic equilibria. This is probably due to the bulkiness of the trimethyl pentenes and steric hindrances especially in 2,4,4-trimethyl-2-pentene molecule. (C) 1999 Elsevier Science B.V. All rights reserved. 

etherification; tertiary ethers; 2-methoxy-2,4,4-trimethyl pentane; 2-methoxy-2-methyl heptane