Process for selective diisopropylation of naphthyl compounds usi

Details Process for selective diisopropylation of naphthyl compounds usi Process for selective diisopropylation of naphthyl compounds usi

1989-12-12

1991-06-25

Garvin, Patrick P.

Chemistry of hydrocarbon compounds

Aromatic compound synthesis

By condensation of entire molecules or entire hydrocarbyl...

585466, C07C 268

Patent

active

050269429

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates generally to isopropylation of naphthyl compounds to obtain diisopropylnaphthalenes, and more specifically this invention relates to the use of shape selective catalysts whose pores are configured to selectively obtain the desired 2,6-diisopropylnaphthalene isomer while minimizing the production of undesirable diisopropylnaphthalene isomers, triisopropylnaphthalenes and tetraisopropylnaphthalenes.


BACKGROUND OF THE INVENTION

A new class of thermoplastic polymers, known as thermotropic liquid crystal polymers ("LCP"), has recently been introduced to the marketplace. These polymers combine the advantageous feature of moldability with multidirectional mechanical strength superior to other thermoplastics formerly available. Generally, these new LCP materials are polyesters made up of planar, linear disubstituted aromatics. Examples of some LCPs currently in use are p-hydroxy-benzoic acid, p-hydroquinone, 4,4'-dihydroxybiphenyl and 2-hydroxy, 6-napthenoic acid.
Other LCPs would appear commercially attractive if either 2,6-dihydroxynaphthalene or 2,6-dicarboxynaphthalene were readily available. Unfortunately, these materials are not commercially produced because cheap, readily available feed stocks do not exist. A viable feed stock, which is convertible into either the dihydroxy or dicarboxy monomers, based upon known technology, is 2,6-diisopropylnaphthalene.
Before proceeding with any description of the isopropylation reaction system, it is important to first review the nomenclature and numbering scheme for the various substituted naphthalene isomers. Equation 1 shows the positional reference numbers. Non-hydrogen bearing carbons are unnumbered because no substitution takes place in these positions. ##STR1##


EQUATION 1

There are two possible isomers which are formed in the monoisopropylation of naphthalene. Substitution occurs only in the 1 and 2 positions and is respectively denoted .alpha. and .beta.. Any monoisopropyl substitution which takes place in positions 3 through 8 identical to the .alpha. and .beta. positions due to their interrelationship in symmetry.
Multiple naphthalene isopropylation is usually denoted by the position number. Some literature references follow the numbering convention just described, while other references discuss the isomers in terms of the .alpha. and .beta. terminology. Thus, the 2,6 isomer is the double .beta. isomer.
Table 1 describes the statistical distribution of the various diisopropylates using these designations, and assuming that no ortho diisopropylation occurs, e.g., 1,2-, 2,3- and 1,8-diisopropylnaphthalene. In Table 1, it is shown that there are seven disubstituted isomers, of which two of them, (2,6- and 2,7-) are the double .beta. product.


TABLE 1 ______________________________________ NORMALIZED TYPE ISOMER EOUIVALENTS FREQUENCY ______________________________________ .alpha.,.beta. 1,6 1,6 = 4,7 = 2,5 = 3,8 2 1,7 1,7 = 4,6 = 3,5 = 2,8 2 1,3 1,3 = 2,4 = 5,7 = 6,8 2 .alpha.,.alpha. 1,4 1,4 = 5,8 1 1,5 1,5 = 4,8 1 .beta.,.beta. 2,6 2,6 = 3,7 1 2,7 2,7 = 3,6 1 ______________________________________
In any manufacture of diisopropylnaphthalene, it is clear that some monoisopropyl- and triisopropyl-products and a mix of diisopropyl isomers will also be obtained. In any crude diisopropylnaphthalene product which is not particularly enriched in one diisopropylnaphthalene isomer, isomer separation by thermal distillation is very inefficient and difficult because the boiling points of 2,6-diisopropylnaphthalene and 2,7-diisopropylnaphthalene are very close. Similarly, diisopropylnaphthalene isomer separation by fractional crystallization using melting points is inefficient and suffers from yield problems because of the loss of the desired product in the mother liquor, and because of large recycle streams.
The present invention provides a process for reacting a naphthyl compound selected from the group comprising naphthalene, monoisopropylnaphthalene and mixtures thereof, with a propyl co

REFERENCES:
patent: 3631120 (1971-12-01), Eberly, Jr. et al.
patent: 4415544 (1983-11-01), Kokotailo et al.
patent: 4440871 (1984-04-01), Lok et al.
patent: 4567029 (1986-01-01), Wilson et al.
patent: 4891448 (1990-01-01), Garces et al.

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