DE1543548A1 - Process for the preparation of substituted 4,6-dinitrophenols - Google Patents

Description

*. «*« · 15435A8

ETAT PBANQAIS, represent * »pax Xe Minlstr · des Army *, Tenants pour l * ArmeBent (EdBBCTIOIf 1X8 PO (JXBBS), Paris

Process cur making τοπ substituted ^, ^ - Dinltro-

phenols

The invention relates to the preparation of substituted 6, 6-dinltrophenols by direct nitration of the corresponding substituted phenols solely by dilute nitric acid without the use of organic solvents and without prior sulfidation or oxidation of the output product

Numerous processes are known, rarely Dinitrlexn phenols used it as alkylreetene

One of these methods is d '\ $ aan am * lerte phenol in a first stage with a "tt" * vr: ohu3 m \ StehiKisrf # i · acidic sulfurized and then in a eweiten stage sit verdütietf ^ SalpetersKure nitrided or old a nitrate, because "In üegtnw?; - * t ▼ on tfbersohussiger SohwefelsKure nitric acid">: \ ~> and & »a« Ata ^ .itieii »in iz < · *>, since the Vi« ko # itlt bw, ä ¹ * "* .., -"*>. * »- * # *.

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the relatively high consumption of sulfuric acid is disadvantageous.

In the also known nitration with mixtures before; Acetic acid and nitric acid have to have the disadvantage in purchase take that acetic acid is relatively expensive and corrosive.

In addition, the dinitration of various) substituted phenols by first nitroenating them (nltrosatlon) and then the nitrosoderlvat for example with dilute nitric acid oxidizes; this process also comprises two process steps, the first being numerous By-products arise, so that overall a low yield is achieved »

It is also known to have nitriding in two stages, in which in the second stage the intermediate mononitrated product is nitrated with the help of concentrated nitric acid; this procedure also comprises two different procedures S ' steps and the use of concentrated nitric acid is otherwise tricky.

In addition, it was possible to achieve nitration of relatively dilute nitric acid (50 to 60%) in the presence of organic solvents such as carbon tetrachloride or chloroform Final product to 1st;. ",. lerer" and ä. «'-!« 1v τ- ·: -.-' · '-'- te Löev: i ά ^ ΑτΛ *,;. R'X rft ^^ - ijeTl-.rcr-, da desssn

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/ 1 4 3 4 ORIGINAL BATHROOM

In addition, the yield is relatively low and does not work beyond about 80Ji *

The direct nitration of o-cresol ro with the aid of relatively concentrated, 60 to 99 Geic.jSlcer nitric acid is also known; one has it, however, operate in a tubular reactor of irregular shape, which makes it possible to suppress the oxidation phenomena world extent possible that the o 'cresol due to the relative Oxydationsanfälligkeit may occur "Using dilute nitric acid at concentrations below 60 percent"# _f gets so only moderate yields and an incomplete nitration or a noticeable oxidation or both phenomena are observed at the same time

One could then assume, in analogy to the observations made with o-cresol, that the nitration of substituted phenols

with diluted nitric acid with concentrations below 6o # Reason for signs of oxidation and / or incomplete Nitration only low yields of dinitrated derivatives

In contrast, however, it has now been established that in the direct nitration of certain substituted phenols by the action of dilute nitric acid alone, »Jt t A concentration below? 0% by weight without the use of organic Solvents and without previous sulfurization or nitrosieiu the starting materials only a very little or no oxidation takes place and that the yields of dinitrated compounds based on the substituted phenols used, higher or

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are equal to Q0% .

Eb is also surprising that such a direct Nitration is only applicable to a special group of substituted phenols, which are identified in more detail below will; these phenols have specific substituents on be "tlMKt" B Have places of the benzene nucleus.

The present invention therefore relates to a method! to the Production of substituted 4-, 6-dinitrophenols of the Poreel «

OE

O ₂ K

in which R _{1 is} an alkyl radical with at least two carbon atoms or "in optionally substituted cycloalkyl", aralkyl or aryl radical and B ₂ hydrogen ("the alkyl means! in the past, the alkyl or cycloalkyl radicals have higher * about 9 carbon atoms Process by Her » the position of these products is that they

OH tea phenol of the molded ice

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in which R ₁ and B _{2 have} the meaning already given * bucket direct nitration solely by dilute nitric acid with a concentration below 70 % by weight and preferably from 30 to 60% by weight at a temperature that is higher than .10 ° c is less than or equal to the boiling point of the reaction mixture under the selected pressure, using such an amount of nitric acid that the content of the remaining acid after the reaction is at least 1 %.

You can work under normal pressure or under Overpressure or underpressure or in a vacuum.

Ran can prevent contact between the substituted phenol and the dilute nitric acid by dispersing the phenol promote or improve in the aqueous nitric acid solution by vigorous stirring or by introducing an emulsion or an aqueous suspension of the phenol in the nitric acid solution »

Contacting the reagents or reaction partners can be carried out discontinuously, in particular by introducing the phenol into the nitric acid, or simultaneously Total introduction of the bite> n reaction partners at the bottom of a ReaktVonegefäfles (dans un pled de cuve).

The nitration can be carried out by continuously adding nitric acid with a concentration higher than 70 £ at the bottom of a reaction vessel with a weaker acid, the ftehalk of which remains within the specified limits of b% to 7θ £,

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The process can also be carried out continuously, for example by introducing or passing the two through Reaction partner In or through an effective mixing device, such as a centrifugal or centrifugal pump, a converging divergent mixer, a cyclone or an emulsifier, the mixture then being fed into a tubular reactor or enters one or more pots with overflow; the mixture can also be poured directly into a mixing vessel with an effective stirrer and overflow are introduced. Allows good dispersion a completion of the reaction in very short times of the order of a few minutes

The reaction can take place at ordinary temperature or even at lower temperatures, but it proceeds then slowly and it is interesting to see the reaction between 3G ° C and the boiling point of the reaction mixture below that for the Carrying out the reaction to carry out the selected pressure; Since the nitrification reaction is exothermic, various known measures can be taken to maintain the temperature take it alone or in combination »For example, vessels with a double jacket can be used for temperature control or feed in the reagents at ordinary temperature and the selected temperature using the one released Maintain heat of reaction

You can of course use a molar ratio of ENT « apply to phenol, which can reach any level, but too high a ratio causes unnecessary consumption

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of nitric acid if it is not recovered after decanting the final mixture and separating the dinitrated derivative ticked. Such a return, however, requires a slight completion of the system, but it can be a "rough" Allow reaction and better temperature control.

The minimum colouration of ENT to phenol to be used depends on the content of the nitric acid used, the reaction temperature and the contact time of the reagents; it will determined on condition that dinitration can be achieved without the reaction stopping at monotransformation; compliance with this condition depends on the salary of the Nitric acid at the end of the nitration, taking into account the quantities of reagents used and their concentrations below assuming a quantitative yield of nitrated phenol can be calculated

After completion of the dinitration, the filtered phenol is isolated using methods known from the physical Depending on the nature of the dinitrided product and among which, for example, decanting or filtering after one Cooling should be mentioned · The product is then washed kit water and, if necessary, dried.

The products obtained give a characteristic ΙΕ spectrum; they know immediately used or welter ▼ be developed for agricultural needs »

Non-limiting examples follow by way of illustration

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- 8 -the implementation of the method according to the invention.

example 1 Nitration of o-ethylphenol

It is poured rapidly, with continuous vigorous stirring, 20 g of a mixture of equal parts by weight ethyl phenol and Wa * ·· * In the form of a with the aid of a wetting agent (Arylalkylsul- · sulfonate) prepared emulsion In 150 g 30 # 1β "Salpetereäure of 80 ⁰ C. The temperature increases to 100 ⁰ C. This temperature is maintained for 2 minutes; it is cooled from the outside with an ice-water bath and the oil obtained is decanted, which is washed with water. M & n receives 13.5 K of the 4,6-nitrile derivative with a yield of 7% and a 92% content an 2-ethyl- ^ _t 6-dinitro3.henol

Example 2 Nitration of o-isopropylphenol

27.2 g (1.5 col) of o-isopropylphenol are rapidly poured into 5 g 50% nitric acid at a temperature of 10 ° C. Dl temperature increases to 100 - 105 ° C. You hold this Tempex for 2 minutes upright and then cools from the outside. One decants, wakes up with water with 1% arylalkylsulfonate netssaittel

One obtains eo * K) g of the nitrated derivative "old 3ln" r Yield of 92%. The crude product has a content of 95% 2 ~ 18opropyl-4,6-dinitrophenol / Ppt ^ 6 ° C (literature> 54 ° C).

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Example 3
Nitration of o-isopropylphenol

At the bottom of a vessel with 50 g of 20 # nitric acid from 20 ° G is left at the same time: in 10 minutes 27.2 g (1/5 mol) Pour in o-isopropylphenol and 30 g of 98 # nitric acid. the The temperature rises fairly quickly and reaches 9 ^ ° C towards the middle the pouring process, the mixture is kept boiling for 5 minutes after pouring, then cooled from the outside with an EAs water bath off, filtered and washed with water.

This gives kl ρ (yield 91.5 #) of the nitrated derivative with a content of 91.5 % of 2 ~ isopropyl- ⁱ l ·, 6-dinitrophenol;

Example 4
Nitration of o-tert-butylphenol

It is poured rapidly 6o g of an emulsified with addition of a ArylalkylsuV-sulfonate wetting agent mixture of equal parts of o-tert-Butylpheriol and water in 90 g $ 0 $ nitric acid of 10 ⁰ C. The temperature rises to 100-106 ° C. This temperature is maintained for 2 minutes, then cooled from the outside with an ice-water bath and filtered and washed with water. The dinitrated derivative (41 g) is thus obtained with a yield of 85.5%. The crude product has a 2-terfc content of 6%. ■ Butyl-i ^ -dinltrophenol Pp: 120 ° C (literature * 132 ° C).

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BAD ORlG ¹ NAL Example 5

Nitration of o-tert-butylphenol

At the bottom of a reaction vessel containing 50 g of 2D% strength nitric acid at 20 ° C., 30 g (1/5 mol) of o-tert-butylphenol and 35 g of 80% nitric acid are allowed to flow in simultaneously over a period of 10 minutes. The temperature rises fairly rapidly and reaches the middle of the Elngießens 96 ⁰ C is obtained for 5 minutes after pouring boiling and then cooled from the outside by a Els-water bath from ₉ filtered and washed with water.

This gives ^ 3 * 5 S (yield: 90.5 #) of a nitrated derivative with 92.8 # of 2-tert-butyl- * i-, 6-dinitrophenol; Mp: t17 ° C

Example 6

Nitration of o-tert-butylphenol

The mixture is poured 30 g o-tert-butyl-phenol (1/5 mole) in 300 g # 4o nitric acid of 55 ⁰ C under reduced pressure of 80 mm Hg, temperature raid pressure are constant · throughout the duration of the operation After after cooling, it is filtered and washed with water.

39 g (yield: 81.5 #) of the nitrated Der Wate are obtained in this way With a content of $ 95 in 2-part, butyl-4-, 6-dinitrophenol Pp: °

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Example ? Nitration of o-sec-butylphenol

20 kg / h are brought into a continuously operating mixer with an attached tubular reactor under a pressure of 3 bar o-sec, -butylphenol and 60 kg 50% nitric acid. The reaction temperature in the mixer and tube reactor is 125 ° C. Man catches the nitration product in water, washes what is obtained 2-sec «-Butyl-4,6-dinltrophenol with hot water and thus obtained 28 kg / h 2-8ek.-Butyl - **, 6-dinltrophenol with a yield before » 87 *.

Example 8 Nitration of o-phenylphenol

It has a rapid and 3 ^ g (1/5 mole) of finely ground o-phenyl · - · phenol in 90 g of 50 # lge nitric acid at 50 ⁰ C. The temperature rises to 100-105 ⁰ C. This temperature is maintained two minutes "long upright, then cools from the outside with an ice-water bath and filtered and washed with water. The nitrated derivative (A8 g) is obtained in a 92% yield. The crude product has a 2-phenyl- * t> 6-nitrophenol content of £ 93.6 Mp 196 ⁰ C (literature, "2O6 ° C).

Example 9 Nitration of o-cyclohexylphenol

35t2 g of o-cyclohexylphenol (1/5 mol) are poured rapidly into 909839 / U84

100 g of 50 £ nitric acid at 50 ° C. The temperature rises to 100-105 ⁰ C, This temperature is maintained for 2 minutes upright, then cooled from the outside with an ice-water bath, filtered and washed with water. The dinitrated derivative (^ 9, ^ g) is obtained with a 93.5% yield. The crude product has a content of 96 # of 2-cyclohexyl-fr _t 6-dinitrophenol Ppt 90 ⁰ C (theory «108 ° C}.

Example 10 Nitration of o-benzylphenol

It is poured rapidly 18 g o-benzylphenol in 55 g 5>#. 8 "nitric acid of 20 ° C, the temperature rises rapidly to 100 ⁰ C. It erhtt'U for 2 minutes at the boil and then cooled with an ice-water Bathroom off. A nitrated oil (20.5 βΐ with a content of 95 »T ^ of 2-benzyl-4,6-dinitrophenol is obtained with a yield of 77%.

Example 11 Nitration of o- (p-chlorobenzyl) phenol

21.8 g (1/10 mol) of o- (p-chlorobenzyl) phenol are quickly added to 75 g of 5Q nitric acid at 70.degree. The temperature rises very rapidly to the point of boiling, which is maintained for two minutes. It is then cooled from the outside using an ice-water bath, filtered and washed with water. 28.3 g (yield: 88.5 pounds) of nitrated product are obtained with a potentiometrically determined content of 93% of 2- (ρ-0η1οΛβηζν1) .4,6-α1η1 ^ ορηβηο1 | Pp: 87 ⁰ C recrystallized from methanol; Mp * 112 ° C.

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Example 12 Nitration of 2-tert-butyl-5-methylphenol

32.8 g (1/5 mol) of 2-tert-butyl-5-methylphenol are poured into 100 g of 50% nitric acid at 50.degree. The temperature rises to 100 ° C in a few seconds. After boiling for 2 minutes, it is cooled with an ice-water bath. This gives a nitrated derivative (^ g) in a yield of 8 ^, 3% and a content of 85Ji of 2-tert-butyl - ^, 6-dinitro-5-methylphenolj mp 86.5 ⁰ C (literature " ⁰

The preceding examples demonstrate that that of the above Substituted phenols corresponding to the formula given special group of compounds form by direct Nitric acid nitration according to the invention Give filtered derivatives with increased yield and satisfactory quality.

On the other hand, it is surprising that substituted phenols with a very similar structure, but which do not correspond to the definition given, only yield mononitrated derivatives or a mixture of hononitro, dinitro and folynitro compounds or are completely oxidized by direct nitration _Λ as in the following examples remove 1st; The substituted phenol used as starting materials in these examples contain an alkoxy, carboxy or Carbelkox / -substituent in ortho-position or they also have a substituent in para

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position·

Example 13 Nitration of guaiacol (or o-methoxyphenol)

The guaiacol is completely oxidised by 30 # lge nitric acid at 20 ⁰ C. You get some black smears,

Example I ^ Nitration of o-hydroxyaeetophenone

Quickly pour 2.2 g (1/5 hol) into 80 g of 50% nitric acid at 60 ° C. The temperature rises by itself to boiling. Are obtained for two minutes at the boil, then cooled with an ice-water bath, and 30 g of an oil with a content of ty% 2-Aeetyl-4,6-dinitrophenol, and 59 # 2-acetyl - ^ - nltrophenol, , ie on a mononitrated compound.

Example 15 Nitration of salicylic acid

One surprising glest 27.6 g (1/5 mole) of salicylic acid in 110 g of 50 £ lge nitric acid of 50 ⁰ C · The temperature rises 100 ⁰ C. It is cooled with an ice 8 en-water bath after two minutes Si edenlas. One obtains with a 73% yield if-nitro-saelioic acid (27 fc) f PpJ 193 ° C.

Example 16 Nitration of

Rapidly one gives 30 Λ ß (.1 / 5 & ol) of methyl salicylate in 110 g of 50 # lge Salpeteroäure of 80 ⁰ C. The temperature rises to 100 ° C. After boiling for two minutes, the mixture is cooled and 36 g of a nitrated derivative with a content of 31% of methyl 1-6-dinitro-salicylate and 65% methyl 1-4-nitro-salicylate are obtained.

Example 17 Nitration of p-phenylphenol

Is brought rapidly in two Hinuten 17.I g (1/10 mol) of p- £ he "y3 ~ phenol in k5 g 50 # Salpetereäure strength of 80 ⁰ G. The temperature rises to 93 ° C. After boiling for two minutes, it is cooled down with an Els Waaeer bath.

This gives 20 g of a mixture of mono-, 2,6-di- and 2 _t 6.4 ^t -trinltrov * rolls; Pp * 130 ° C (Pp of the delta connectionf

Example 18 Nitration of p-tert-butylphenol

Is brought rapidly in a few seconds, 20 g of p-tert-butylphenol in 90 g of nitric acid 50Jilge 50 ⁰ C. The temperature rises by itself to 98 ⁰ C. It is k * 'hlt by a bis-water bath after two minutes Sledenlassen · 23 g of a nitrated derivative with a nitrogen content of 15.5 ^ (mp * 65 ^° C.) % mp are obtained theoretically 97 - 98 ⁰ C.

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Example 19 Nitration of p-isooctylphenol

41.2 g (1/5 mol) of p-Iaooctylphenol in 180 g of 50% nitric acid at 60 ° C. are added in two minutes. The temperature rises to 98 ^° C. It is boiled for 10 minutes, then cooled using an Els water bath and 56.5 β of an oil is obtained. The nitrogen content is 12.8 ^. (Theoretical nitrogen content of the nitrated derivative? 9.4?).

Example 20 Nitration of p-nonylphenol

Is brought rapidly in a few seconds, 44 g (1/5 mol) of p-nonylphenol in 180 g of 50 # lge nitric acid of 60 ⁰ C. The temperature rises to 98 ⁰ C for 10 minutes is brought to the boil. After cooling, 59 g of an oil with a nitrogen content of 11.94 are obtained. The nitrogen content of the nitrated derivative is 9.34.

The phenols substituted in the para position (Examples 17 to 20) give nitrated derivatives with a nitrogen content of is significantly higher than that of the filtered derivative. the aoidimetric determination generally gives several levels or Unschlagpunkt (vlrages), which the presence of at least appear to indicate nitrated derivatives

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Successive crystallizations of the products obtained after nitrating p-tert-butylphenol, p-isooctyl- and p-nonylphenol from methanol make it possible to isolate a nitrated compound with a nitrogen content of 18.33; Pp ', 120.8 ⁰ C. Molecular weight: 229 · One can conclude from this that picric acid (melinite) is present ·

About 60 # picric acid is obtained in the case of p-tert-butylphenol and $ 25 to $ 30 in the case of isooetyl and nonyl phenol

The direct nitration of p-phenylphenol did not produce any Picric acid isolated, but trinitrophenylphenol.

In addition, the present method is for the direct NIt. ration of o-methylphenol to obtain 2-methyl - ^, 6-dinitrophenol not applicable.

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Claims (4)

Claims 1, Process for the production of substituted ^^ - Dinitrophenols *) the formula: OH NO, in which R _{1 is} an alkyl radical having at least two carbon atoms or an optionally substituted cycloalkyl, aralkyl or aryl radical and R _{2 is} hydrogen or alkyl, characterized in that a substituted phenol of the formula In which R- and R "have the meaning already given, a direct nitration with dilute nitric acid alone at a concentration below fO wt of nitric acid, that? the final content of the remaining acid after the 9U9839 / U84 BAO ORIGINAL Nitration is at least k% . 2. The method according to claim 1, characterized in that nan works under superatmospheric pressure. 3. The method according to claim 1, characterized in that one works under negative pressure. 4. The method according to claim 1, characterized in that the substituted phenol and nitric acid with a concentration equal to or above? Oji at the bottom of a reaction vessel with dilute acid is allowed to flow in, the content of which remains below 70%. 909839/1484 BATH