Author Topic: Friedel-Crafts Modification with Nitroparaffins  (Read 1296 times)

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Aurelius

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Friedel-Crafts Modification with Nitroparaffins
« on: July 14, 2003, 11:12:00 AM »
US Patent 2385303

Alkylation of Aromatic Compounds


Abstract:

This process is concerned with a method for mono-alkylating aromatic hydrocarbons by olefinic hydrocarbons using a Friedel-Crafts-type catalyst dissolved in a nitroparaffin to effect the reaction.  Alkene-producing substances may also be used as a reactant, though generally under different reaction conditions from the alkene for which they would be used.


*all “parts” are by weight unless otherwise speficified

Example 1:

4 parts of AlCl3 dissolved in 5.7 parts of nitromethane formed a pale yellow solution to which 55 parts of benzene was added to form a light yellow solution.  The last-named solution was placed in a reactor cooled to 0*C and 12 parts of propene was passed thereto over a period of 2.5 hours during which the reation temperature, because of exothermic heat of reaction, was allowed to increase to 40*C under 1 atm.  The clear yellow product so obtained was washed with water, then with sufficient dilute sodium hydroxide to dissolve the precipitated aluminum hydroxide, finally dried and distilled to yield 20 parts of mono-isopropyl benzene, 8 parts di-isopropyl benzene and 2.5 parts of higher boiling material.

Similarly, 1 part of AlCl3 was dissolved in 2.3 parts of nitromethane and added to 80 parts benzene.  This catalyzed the reaction with 15 parts of propene at 30-40*C to form 26 parts mono-isopropyl benzene, 10 parts di-isopropyl benzene and 5 parts of higher boiling material. 

Example 2:

Only small amounts of ethylbenzene were obtained when ethylene was reacted with benzene as Example 1.  Good yields were obtained at higher temperatures of 40-65*C under about 40 atm in the presence of HCl and AlCl3 dissolved in nitromethane.  Thus a solution of 8 parts AlCl3 in 10 parts nitromethane and 80 parts benzene and 3 parts of HCl were mixed in an autoclave to which ethylene was added until a pressure of 40 atm was achieved.  The reaction temperature was kept at 25*C for 1 hour and then increased to 40*C for 4 hours and finally to 65*C for 3 hours. The resulting product yielded 12 parts ethylbenzene and 6 parts of more highly-alkylated materials.

Example 3:

A solution containing 5 parts of AlCl3 dissolved in 5.7 parts of nitroethane mixed with 80 parts of benzene and propene was bubbled into the solution at 0*C and later at temperatures up to 40*C at 1 atm until 24 parts of propene had been added over three hours.  The resulting products contained 31 parts isopropylbenzene, 16 parts di-isopropylbenzene and 7 parts of higher boiling material.

Example 4:

6 parts propene at 25 *C and 1 atm were added to a pre-made solution of 40parts benzene, 4 parts AlCl3 in 7.5 parts 2-nitropropane.  The reaction products yielded 9.5 parts isopropylbenzene, 4.5 parts di-isopropylbenzene and 3 parts higher boiling material.

Example 5:

A clear yellow solution was formed using 10 parts anhydrous aluminum chloride and 15 parts 2-nitropropene.  Upon addition of this solution to 80 parts benzene a clear red solution formed.  No heat was evolved.  The addition of 0.5 parts of di-isobutylene caused the red solution to turn yellow again.  More alkene was added with shaking in portions of 5-10 parts until 32 parts was added at 1 atm.  The reaction mixture was kept between 35-40*C with a cooled water bath.  The resulting solution after washing and drying was found to contain 4.5 parts t-butylbenzene and 38 parts of higher boiling material.

There were more examples, but they had no significant changes from the examples above. (one did include an alkyl halide instead of an alkene, but that is well covered elsewhere.


Rhodium

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Related threads
« Reply #1 on: July 17, 2003, 06:06:00 PM »
Threads related to the Allyl-OH/K-10 clay FC alkylation above includes the following:

Post 103617 (missing)

(Scooby Doo: "Alkylation of 1,3benzodioxole with K10", Chemistry Discourse)

Post 108727 (missing)

(dormouse: "Allylpyrocatechol question  -bloodgod100", Novel Discourse)

Aurelius

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Sorry about that
« Reply #2 on: July 17, 2003, 11:23:00 PM »
I had intended to include those links, but I ran out of time