Chemistry of hydrocarbon compounds – Plural serial diverse syntheses – To produce aromatic
Patent
1998-03-20
1999-09-14
Griffin, Walter D.
Chemistry of hydrocarbon compounds
Plural serial diverse syntheses
To produce aromatic
585411, 585418, 585420, 585421, C07C 1524
Patent
active
059525347
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL AREA
The invention is related to the manufacturing of 2,6-dimethylnaphthalene from p-xylene and 1- or 2-butene or butadiene via the intermediates 1-(p-tolyl)-2-methylbutane or 1-(p-tolyl)-2-methylbutene. 2,6-dimethylnaphthalene can be used as a raw-material for manufacturing of polyethylenenaphthalate.
TECHNICAL BACKGROUND
Polyethylenenaphthalate (PEN) has got very good mechanical strength and heat resistance. Its known manufacturing processes, however, have not been competitive.
Polyethylenenaphthalate is made from 2,6-naphthalenedicarboxylic acid, which is made by oxidizing 2,6-dimethylnaphthalene. Nowadays 2,6-dimethylnaphthalene is separated from hydrocarbon mixtures. In this way only small amounts are obtained. Furthermore also the separation and purification is difficult.
It has also been suggested to manufacture 2,6-dimethylnaphthalene by cyclization of 1-(p-tolyl)-2-methylbutane and/or 1-(p-tolyl)-2-methylbutene.
The manufacturing of 2,6-dimethylnaphthalene has been described in many patents. In some of these patents also the manufacturing of 1-(p-tolyl)-2-methylbutane and/or 1-(p-tolyl)-2-methylbutene is described. In some patents also the use of chromium oxide/aluminum oxide and its impregnation with potassium is mentioned.
In GB-1448136 (1976) the manufacturing of 1-(p-tolyl)-2-methylbutane and/or 1-(p-tolyl)-2-methylbutene in many different ways is described. In most cases one component is p-xylene, the methyl group of which is alkylated with butene using a basic catalyst. In three examples the manufacturing of 2,6-dimethylnaphthalene using a Cr.sub.2 O.sub.3 /Al.sub.2 O.sub.3 -catalyst poisoned with potassium is described. In the claims the amount of impregnated alkali metal oxide is 0.1-20 wt. % but in the examples the amounts of potassium are 2.1 and 3.5 wt. %. However, 3.1% and 5.0% of the total amount of dimethylnaphthalene is 2,7-dimethylnaphthalene which is very difficult to separate.
In EP430714A (1990) a chromium oxide/aluminum oxide catalyst poisoned with potassium is mentioned in one example but in the claims only the oxides are mentioned but not the amounts. In one example the components K:Cr:AL are in the proportions 7:11:100. In the same example the proportion of 2,6-dimethylnaphthalene of the total amount of dimethylnaphthalenes is 98.6%.
In EP-362507A (1989) p-xylene, 1-butene and carbon monoxide are used as raw-materials when making 1-(p-tolyl)-2-methylbutane and/or 1-(p-tolyl)-2-methylbutene. When making the 2,6-dimethylnaphthalene Cr.sub.2 O.sub.3 -5% K.sub.2 O-Al.sub.2 O.sub.3 is used as catalyst The selectivity of 2,6-dimethylnaphthalene was reported to be 71%. Nothing is mentioned about the purity of the product. In the claims only aluminum oxide and silicon oxide are mentioned.
EP-362651A (1989) is almost the same as EP-362507A regarding the dehydrocyclization reaction. The only difference is that m-xylene, propylene and carbon monoxide are used for making 2,4-dimethyl-isobutyrophenone, which is cyclisized to 2,6-dimethylnaphthalene.
In the patents mentioned above nothing is said about C12-alkylindanes and -indenes which are very difficult to separate because they are boiling at almost the same temperature as the dimethylnaphthalenes.
DESCRIPTION OF THE INVENTION
Now the process described in claim 1 has been invented. Some preferable process alternatives are presented in the claims.
The reactions according to the invented process are described below: ##STR1##
In reaction step 1 the alkylation of the benzyl side chain is done so that the amount of n-alkyl compounds is minimized. For this purpose some basic catalysts are therefore most appropriate.
In reaction step 2 on the other hand the aromatic dehydrocyclization is done using a Cr.sub.2 O.sub.3 -, V.sub.2 O.sub.5 - or Pt-catalyst.
According to the first aspect of the invention p-xylene is reacted with butene or butadiene to p-(2-methylbutyl) toluene or p-(2-methylbutyl) toluene using an alkali metal as catalyst and this catalyst is preferably attached to a suitable support. As a catalyst one can use for
REFERENCES:
patent: 3931348 (1976-01-01), Taniguchi et al.
patent: 5276230 (1994-01-01), Inamasa et al.
patent: 5321178 (1994-06-01), Inamasa et al.
Chemical Abstracts, vol. 84 (1976), 4735a Japan 75-17,983, No Month Available.
Csicsery Sigmund M.
Halme Erkki
Koskimies Salme
Laatikainen Markku
Niemi Vesa
Griffin Walter D.
Optatech Oy
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