DE2243112A1 - PROCESS FOR PRODUCING NITRODE DERIVATIVES FROM SUBSTITUTED AROMATIC COMPOUNDS - Google Patents

Description

Dr. F Zumstein sen. - Dr. E. Assmann 2? A * 3 1

Pr. R. Kooniiir.bergo '- Dipl. Phys. R. HolxbaueT * " * · 7 ^ '

Dr. F. Zumstein jun.

Patent attorneys

8 Munich 2, Bräuhausstraße 4 / III

Case 505
WTZW

SNAM PROGETTI S.p.A., Milan, Italy

Process for the preparation of nitroderivatives of substituted

aromatic compounds

The invention relates to a process for the production of nitro derivatives of substituted aromatic compounds *.

It is known to have a functional N0 ₂ group in the side chain

ί of, for example, hexamethylbenzene to be introduced. This implementation

^; takes place by a halomethylpentamethylbenzene with AgNO ^

<implements. This method is described by H.Suzaki in Bull-Chem. Soc. Japan

! £ 3, 879 (1970). With this procedure, one obtains every

: but low yields and to produce the desired product

■ several stages are required.

It has now been found that the nitration of a side chain
"of a substituted aromatic compound achieved directly

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can be, if such compounds with a mixture of HNO, and an organic anhydride, preferably acetic anhydride, implements. Nitro derivatives of substituted aromatic compounds can be used in this way in a simple and inexpensive manner can be produced with better yields than in the known process.

Acetates and nitrates are used as the starting material as by-products substituted aromatic compounds used. These can be easily separated.

The term "substituted aromatic compounds" as used in the present application means compounds of the formula CgR X, in which Cg is the known benzene nucleus, which contains 6 carbon atoms, and R and X substituents which are bound to the aromatic nucleus, mean. In the formula, the radicals R denote which are bonded to the aromatic nucleus are, (a) monovalent hydrocarbon radicals with at least one hydrogen atom in the α-position or (b) two of the radicals R form with the benzene ring a ring, each of the radicals R being a divalent hydrocarbon radical, or (c) the R radicals can represent a combination of (a) and (b), whereas X represents another substituent which is capable is to attack the free position on the carbon atoms of the benzene ring and where X is a monovalent substituent such as hydrogen, halogen, CN and others and where η and m represent whole numbers so that the sum of m and η means 6.

When R represents (a), R can represent methyl, ethyl, propyl, isopropyl, butyl, and others. If R is methyl and m = 0, is the aromatic compound hexamethylbenzene. This connection is preferred because it is readily available.

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Other compounds used in the present invention are substituted naphthalenes of the Por-

mel. . ... * ■.

In such a pail it is sufficient that the above-mentioned Substituents in the para positions 1, 4 and / or 5, 8 are present.

If substituted benzene is used, which has a number of substituents which is less than 6, nitration takes place on the side chain if the choice of substituents is so chosen found that the aromatic compound is particularly reactive with electrophilic reactants.

As examples of compounds in the invention Procedures can be used, the ^ following ver. bonds are called

The compounds according to the invention are based on many Areas of organic "'synthesis and as. Industrial products valuable.

-The introduction of the NOp function can result in direct connections, for which there is an industrial need. These

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Function can also be performed according to other methods for amine function be reduced or substituted for another function. The products according to the invention can therefore be used in the Synthesis of nitro derivatives, amine compounds, dyes, pharmaceutically active compounds, fibers, etc. can be used.

The method according to the invention can also be used to modify products as mentioned above, also if the the latter are present in the polymer chains. Interesting applications of the present invention are introduction of NOp groups (and those derived from them) and of Acetoxy and hydroxyl groups in the side chains of aromatic polyalkyl derivatives.

The process according to the invention is explained in more detail using the example of hexamethylbenzene, since this is a product that is readily available. A mixture of acetic anhydride and HNO ₅ with a concentration of 65 $ is used. The reaction is carried out in the liquid phase at room temperature. It can also be carried out at higher or lower temperatures. The pressures are selected so that the system is and remains essentially in the liquid phase. From a practical point of view, the aromatic compound is reacted with the anhydride and this mixture is then added, preferably with stirring, to the nitration mixture which contains HNO and further acetic anhydride. Depending on the working conditions chosen, the mixture is reacted for a few hours and then the compounds obtained are separated. The following example explains the invention without, however, restricting it.

example

A nitration solution is at 30 ⁰ C through a dropping funnel and

3 0 9 8 11/113 3

added with stirring to a solution which contains 3 g (1 | 85.10 "mol) of hexamethylbenzene in 400 ecm acetic anhydride. The nitration solution was prepared by adding 1.28 ecm HNO, with a concentration of 65 i ° d = 1 , 4 to 10 cc of acetic anhydride was added while cooling in an ice / salt bath, and after 24 hours the mixture is poured onto ice and water.

After the hydrolysis, neutralization is carried out first with Na ₂ CO ₅ and then with NaHCO ₅ and then extracted with ether. The yellow crude product, about 3.6 g, which is obtained after evaporation of the ether, is chromatographed on silica gel using ligroin and benzene used in a 4: 1 ratio as an eluant.

In such a way one obtains about 300 mg and 1.2 g hexamethylbenzene Pentamethylphenylnitromethan (Ep "= 87 and 87.5 ⁰ C. after recrystallization) in the specified elution order.

Pentamethylbenzyl acetate could also be isolated, whereas the nitric acid ether was decomposed to pentamethylbenzyl alcohol.

The reaction mechanism can be shown according to the general scheme that for unusual aromatic electrophiles Implementations was proposed.

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Claims (7)

Claims 1.1 Process for the production of nitro derivatives in the Seirenkette of substituted aromatic compounds, characterized in that the substituted aromatic compound with HNO, in the presence of an organic acid anhydride, preferably acetic acid anhydride. 2. The method according to claim 1, characterized in that the nitric acid has a concentration of 65%. 3. The method according to claim 1 and / or 2, characterized in that one is substituted as the aromatic compound (I) a compound of the general formula CgR _n X _n ., In which Cg is a benzene ring, (a) each of the radicals R is a monovalent substituent such as hydrocarbon radicals or (b) adjacent R are divalent substituents or (c) R is a combination of (a) and (b) denotes, X denotes a monovalent substituent which differs from (a) and (b), such as hydrogen, halogens, CN inter alia denotes, η and m denote integers so that the sum of η and m represents 6, where m can also be O, and (II) substituted naphthalene compounds of the general formula used. 0 9 8 11/113 3 4. The method according to claim 3, characterized in that there is used as the aromatic 'compound hexamethylbenzene. 5. The method according to claim 4> characterized in that the hexamethylbenzene is mixed with acetic anhydride and that this mixture is stirred with a hydrogenation mixture which UNO, and containing acetic anhydride, is treated. 6. The method according to claim 51 characterized in that the temperature is preferably in the range of about 3O ⁰ C. 7. Products produced according to one of the preceding claims. 09 (111/1133