| الملخص: |
Solid support catalysts for three reactions were explored. It was desirable to cause the Diels-Alder reaction of cyclopentadiene and methyl acrylate to be Exo selective. Shape selection catalysis was to be used. None of the solids tested induced the desired product selectivity. However, H Mordenite was found to alter the reaction selectivity, producing far more Exo adduct than is normally found. Also, Synclyst 25 was found to promote production of the Endo adduct. Reaction in the presence of this solid was rapid and highly selective. The Prins reactions of formaldehyde with 1-pentene, 2-pentene and 2-methyl-2-butene were studied. Prins reactions give a mixture of products and use soluble acid catalysts. It was intended that solid support materials should be used as acid catalysts and to exert shape selectivity in these reactions. The chosen Prins reactions were promoted by some of the solids tested but none were as effective as sulphuric acid. Solid supports were used to influence the outcome of the bromination of naphthalene by tertiary butyl hypobromite. This reaction is catalysed by acids. The acidity of the solids tested was used to promote the reaction rate, whilst the solids' shapes were investigated for their ability to control the product distribution. Of the two possible monobromination products usually only 1-bromonaphthalene is formed in free solution as a significant product. A solid was sought that would induce selectivity in favour of 2-bromonaphthalene. Zeolite HL was found to achieve this partially. The reaction still generated 1-bromonaphthalane as the major product but a significant portion of the product was 2-bromonaphthalene. H Mordenite was found to promote the rate of the reaction whilst allowing exclusive production of 1-bromonaphthalene. This was a significant discovery as free-solution bromination of naphthalene usually generates a small portion of 2-bromonaphthalene. |
