DE1153351B - Process for the preparation of nitroacetals - Google Patents

Description

The present invention relates to a new method for the preparation of nitroacetals of the general formula

NO ₂

R —CH, -C-

-O- ACR ₂

Herein, R is a hydrogen atom or an alkyl radical; R ₁ is a hydrogen atom or an alkyl radical; R ₂ is a hydrogen atom, alkyl, halogen, nitroalkyl, nitro, aryl, alkylaryl, arylalkyl, cycloalkyl, haloalkyl or nitrazaalkyl radical; R ₃ is a hydrogen atom, alkyl, halogen, nitroalkyl, nitro, aryl, alkylaryl, arylalkyl, cycloalkyl, haloalkyl or nitrazaalkyl radical, which can be the same as R ₂ or different from R ₂ ; A is an alkylene radical.

The nitroacetals prepared according to the new method, especially the geminal dinitroacetals, are excellent plasticizer in the manufacture of polyurethane binders for high-energy, solid rocket propellants. The acetals are also suitable for plasticizing nitrocellulose and nitro polymers, such as nitro-substituted polyurethane polymers. These plasticizers add to the energy of the Propellant, in which they are given, because of their high nitro content. They are therefore the present Superior to commercially available plasticizers, especially because these products do not have nitro groups and for this reason do not contribute to the energy. In addition, they show This process produced nitroacetals with polyurethane systems in which the monomers contain geminal dinitro or nitraza groups, good tolerance in contrast to almost all other commercial plasticizers that are incompatible with it.

The use of these nitroacetals as plasticizers in nitro polymerization can be done once in be carried out in such a way that the polymerization is carried out together with the plasticizer or the Plasticizer is added after the polymerization. The amount of plasticizer added is moving between about 10 and 40%> based on

NO,

Applicant:
Aerojet-General Corporation,
Azusa, Calif. (V. St. A.)

Representative: Dr.-Ing. K. Boehmert

and Dipl.-Ing. A. Boehmert, patent attorneys,

Bremen 1, Feldstr. 24

Claimed priority:
V. St. v. America January 12, 1960 (No. 2073)

Henry Julius Marcus, West Covina, Calif. (V. St. Α.), Has been named as the inventor

the weight of the mixture. When using the

so acetals as plasticizers for polyurethanes without nitro groups, ζ. B. in the case of polyurethane binders for solid fuels, the same technique is used for the addition used as with nitro polymers. The plasticizers are preferably used in an amount of about 15% based on the total weight, added.

The nitro-substituted polyurethanes can be used as primary sources of propulsion for rocket propulsion Vehicles can also be used as propellants for artillery shells. When using as the primary drive source for rocket vehicles, they can be connected in a known manner with a conventional Ignition means are ignited. The drive means is preferably cast in a tubular shape and confined in the conventional manner with a relatively inert resin. As such, it can be non-nitrided Polyurethane foam or a polyester resin can be used. The drive means is in a Brought chamber that is open on one side and ends in a conventional Venturi rocket nozzle. After Ignition, large amounts of gas are developed, ejected through the nozzle and thereby the driving force generated.

The novel process of this invention consists in the reaction of an alkyl ester of an unsaturated alcohol with a nitro alcohol according to the general formula scheme

R-CH = C-O C-R, + 2HO-A-C R

Ri

R-CH ₂ -C-

NO ₃

-O- AC- R ₅

+ HO-CR ₄

309 669/322

Herein R, R ₁ , R ₂ , R ₃ and A are as defined above and R _{4 is} a hydrogen atom or an alkyl radical. The best results are obtained when the above reaction is carried out in the presence of a small amount of a catalyst. Mercury compounds, such as mercury oxide, mercury acetate, mercury sulfate, mercury halides, mercury nitrates, etc., in combination with sulfuric acid, perchloric acid, boron trifluoride etherate or a strong Lewis acid, such as AlCl ₃ , ZnCl ₂ , etc., are used as catalysts. Mixtures of the above mercury compounds and / or sulfuric acid and their equivalents can be used within the scope of this invention. The relative ratio of the mercury compound (or mixtures of the mercury compounds) and sulfuric acid (or its equivalents or mixtures thereof) is not critical and can be varied within the scope of this invention. Where catalysts are used, they can be used in amounts ranging from mere traces up to about 1% based on the total reaction weight, or even higher amounts.

In order that this invention may be better understood, the following examples are given. You're just supposed to be understood as a means of representation. The invention is not limited to these particular embodiments and the conditions described therein are limited.

30 Example 1

Preparation of acetaldehyde bis (2,2-dinitropropyl) acetal

16.1 g (0.10 mol, 96%) of 2,2-dinitropropanol, 0.1 g of mercury oxide and 0.1 ml of boron trifluoride etherate are placed in a three-necked flask equipped with a stirrer, thermometer, dropping funnel and condenser. 4.3 g (0.050 mol) of vinyl acetate (distilled) are added dropwise to this slurry over a period of 10 minutes. The temperature is kept ^{below 55 °} C. by cooling during the addition. The mixture is stirred for 1 hour and then poured into a mixture of ice, water and 50 ml of 1N sodium hydroxide solution. After dilution with 25 ml of methylene chloride, the organic phase is separated off, washed once with 25 ml of a 1N sodium hydroxide solution and then twice with water. The solution is dried over sodium sulfate and the solvent is removed in vacuo. 11.3 g of a slightly yellow oil remain.

4 g of the crude product are subjected to vacuum distillation. This gives V2 S v ° ⁿ a colorless distillate. Boiling point about 96 to 130 ^° C. at 0.5 mm; nff = 1.4415. Although the steam temperature reached 162 ° C, no more distillate was obtained above 130 ° C. The residue could be recrystallized from alcohol in dry ice-acetone, and with the seed crystals obtained in this way, the remainder of the main part could be brought to crystallize well. The two portions were combined, recrystallized and stored at -20 ° C overnight. The pulp was then washed with cold alcohol and the slightly yellow solid was dried in a desiccator. The acetal gradually melted (expected melting point 28 to 29 ⁰ C) to a clear yellow liquid; n% ⁵ = 1.4617; Yield: 4.5 g (28% of theory). A portion of the product was mm (bulbtube) from a retort at 0.3 and distilled an oil bath temperature of 170 to 180 ⁰ C. The viscous and almost colorless distillate gave «| ⁵ = 1.4606 and the following analysis values for C ₈ H ₁₄ N ₄ O ₁₀ :

Calculated ... C 29.45, H 4.33, N 17.18%;
found ... C 29.89, H 4.60, N 16.36%.

Example 2

Preparation of acetaldehyde bis (2,2-dinitropropyl) acetal

This example describes a laboratory method in which acetaldehyde bis (2,2-dinitropropyl) acetal on a larger scale than shown in Example 1.

A 200 ml three-necked flask fitted with a stirrer, thermometer, The dropping funnel and drying tube are provided with 163 g (1.02 mol .. 99.2% pure) 2,2-dinitropropanol, 20 ml of methylene chloride, 0.6 ml of concentrated sulfuric acid and 1.0 g of yellow mercury oxide Mistake. With thorough stirring, 43.0 g (6.50 mol) of vinyl acetate are obtained within 10 to 15 minutes added at 20 to 25 ° C. The mixture is subsequently stirred for 4 hours.

The reaction mixture is poured into 800 ml of 1N sodium hydroxide solution, stirred well, and the oil severed.

The aqueous phase is extracted with 250 ml of methylene chloride. The combined organic phases are filtered through filter aid, washed once with 200 ml of 1N sodium hydroxide solution and twice with water and dried over sodium sulfate. The methylene chloride solution is through a 30 cm high and an active alumina column 2 cm in diameter. Then will the column was washed with 150 ml of fresh solvent and the two portions were combined. That Solvent is removed in vacuo and a yellow oil remains; Yield: 122 g (75%).

The crude acetal is recrystallized in 185 ml diisopropyl ether at -2O ⁰ C using activated carbon (decolorizing charcoal). The purified light yellow-brown acetal content is 85 g (52%).

Application example 3

Technical preparation of acetaldehyde bis (2,2-dinitropropyl) acetal

This example illustrates an engineering preparation process for the preparation of acetaldehyde bis (2,2-dinitropropyl) acetal described.

procedure

Step I: representation
Step II: cleaning
Yield: 29 to 34 kg (50 to 60%).

Raw materials

for step I: representation

a) 54 kg (350 mol) of 2,2-dinitropropanol (100%),

b) 9.51 CH ₂ Cl ₂ ,

c) 360 g (1.7 g mol) of mercury oxide (reagent quality, yellow powder),

d) 216 ml of concentrated sulfuric acid (96%, 4 mol),

e) 15.3 kg (170MoI) vinyl acetate (with hydroquinone stabilized),

5 6

f) 78 l methylene chloride, always ensure a good separation of the phases

g) 14 kg of sodium hydroxide in cookie form. The pn value of the aqueous solution should after h) pulp powder (filter aid), final wash at 7.0. This is not the case,

i) 3.6 kg of sodium sulfate, washing must be continued until this

j) 285 l of ice water; 5 pH value is reached. The methylene chloride solution is

then mixed with 3 kg of sodium sulfate and 1 hour

for step II: cleaning l ^{stirred at} S ^star k. The sodium sulfate is then

. . ". , r. / -ι ι j

a) a batch of crude bis (2,2-dinitropropyl) acetal ^ _{5 cm thick layer of sodium sulfate is covered>}

,. ™ " ^ - ', .."., Ίο filtered. After the nutsch is about half filled with sodium

b) 95 l of diisopropyl ether. _{sulfate gefüHt} ^ _{wM the filter residue with about}

21 washed fresh methylene chloride and then

Equipment discarded. For the removal of mercury impurities

for step I: representation, the filtrate is

% · ™ i η ι · co mt Ji, _t ι '5 mhiium oxide filled and about 75cm high and im

5 a 200 l reaction vessel (Pfaudler reactor), 14 cm diameter column inside

^em ? «; , -ί- ^0Ρ ί ^e ^ f ^{US T0Sti} ™ ^e ™ f ^tah1 'sent a time of 5 to 15 hours. The filtrate

c em 380-1 tank lined with glass, _{must be perfectly kkr and frd v} ^s _on impurities

d) a 30 cm sieve centrifuge, _his _ _{£ s will then jn a clean} ^ .p ^, ..

e) Give an Ulassmtertncnter, _{2o reactor and} the methylene under vacuum

chloride removed. This happens at a maximum

for step II: cleaning internal temperature of 55 ° C in no more than one

a) a 200 liter reaction vessel (Pfaudler reactor), hour or from 43 ° C within 3 to 5 hours.

b) a 72-1 bottle,

c) a 30 cm sieve centrifuge, ² 5 Step II: cleaning

d) two 50 cm suction cups.

53 liters of diisopropyl ether are added to the reaction vessel

Implementation given, and to dissolve the crude acetal in the

Ether is stirred for 2 minutes at room temperature.

Step I: Preparation _{3o D} j _e solution is then cooled and

The 2,2-dinitropropanol is added with 9.51 methylene -7 ⁰ C seed crystals. The cooling is continued with chloride and mercury oxide in a clean 200-1- with vigorous stirring and the inner Pfaudler reactor is added. While stirring, the temperature of the crystallization mixture is kept at about -20 sulfuric acid within one minute in a thin to -30 ^° C. for 1 hour. Added by a 50 cm beam. The temperature is raised to 20 35 suction filter, the mixture is filtered and the reaction is kept constant up to 25 ° C, if necessary by external cooling, with a total of 361 at -20 to -30 ° C. The vinyl acetate is washed with precooled diisopropyl ether within one hour. The filter admitted. The reaction mixture is after the residue is spread out on a plate and added ^{vigorously for a further 5 hours at 20 to 28 0} C last in the vacuum dryer 48 hours at not over stirred, with moderate cooling, especially at the beginning of t ° 25 ⁰ C,
surgery, may be necessary.

The reaction mixture is then, with moderate application example 4

Stir in a 380-1 tank containing the glass representation of acetone-bis- (2-nitrobutyl) -acetal
is lined and a cold solution of 11.6 kg

Contains (290 moles) sodium hydroxide in 1301 of water. 45 Acetone bis (2-nitrobutyl) acetal is analogous to that

To this end, 42 liters of methylene chloride are added, 5 ml of the method described by the examples above

utes stirred and the solution stand for 20 minutes- reaction of propylene (2-ol) formate with 2-nitro-

left, with the phases separating. The lower butanol in the presence of mercury acetate and

(organic) phase is separated and represented by an aluminum chloride,

30 cm basket with a cellulose powder layer - so

centrifuge filtered. After removal of the methylene application example 5

chloride layer are added to the aqueous solution 111 _{representing n} . _B ut _y raldehyd-bis- (2-chloro-2,4,4-tri-

Given methylene chloride, the mixture 3 minutes ^ °. l-butvlVacetal

vigorously stirred and the lower phase after it is ^y

Has settled for 10 minutes, separated and replaced by 55 n-butyraldehyde-bis- (2-chloro-2,4,4-trinitro-1-butyl) -

Cellulose powder filtered. The cellulose filter layer is acetal is analogous to that described by the above examples.

washed with 41 fresh methylene chloride. by the reaction of 1-butylen-l-ol-

The clear, slightly yellow-colored methylene chloride propionic acid ester with 2-chloro-2,4,4-trinitro-1-butanol

solution is placed in a 200 l reaction vessel, with in the presence of mercury sulfate and zinc chloride

30 1 4% sodium hydroxide solution are added and the ⁶ ° is obtained.

Mixture stirred vigorously for 2 minutes. After ten minutes. ,,. . , _c

The upper layer (aqueous layer) will stand - application example 6

separates and discards. This extraction is illustrated by methyl-n-butyl-ketone-bis- (5,5-dmitro-

another 301 4% sodium hydroxide solution, again 5-phenyl-1-pentyl) acetal

it should be noted that the separation of the G ₅ methyl-η-butyl-ketone bis - (5,5 -dmitro-5-phenyl-

aqueous phase as completely as possible through l-pentyl) acetal according to the above examples

to be led. The methylene chloride solution is finally cited method by reaction of 1-hexene

Lich washed three times with 301 water each time, with 2-ol-n-butyric acid ester with 5,5-dinitro-5-phenyl-l-pen-

tanol in the presence of mercury chloride and boron trifluoride etherate obtain.

Application Example 7 Preparation of isopropyl-n-pentyl-ketone-bis- (2-nitro-4-phenyl * 2-n-propylphenyl-1 butyl) acetal

Isopropyl - η - phenyl - ketone - bis - (2 - nitro - 4 - phenyl-2-n-propylphenyl-1-butyl) -acetal is produced according to the
Method described above by reaction of 3-octylen-2-methyl-3-ol-acetate with 2-nitro- io going description of this process is 4-phenyl-2-n-propylphenyl-1-butanol in the presence of Shechter et al, J. Am. Chem. Soc, 74, 3664

The primary nitro alcohols (other than ß-nitro alcohols) are reduced by reducing the corresponding Acyl halides shown with sodium borohydride. The one for this new process as a reaction partner 4,4-dinitro-1-alkanol useful or used is made by selective reduction of Michael adducts, which then lead to the desired dinitro alcohols are reduced. A one

represented by mercury nitrate and sulfuric acid.

Application example 8

Preparation of acetaldehyde-bis-iS-nitro-S-cyclohexyl-5-bromo-1-pentyl) acetal

Acetaldehyde-bis- (3-nitro-3-cyclohexyl-5-bromo-pentyl) -acetal is made according to the method described by the above examples by reacting vinyl n-valerate with S-nitro-S-cyclohexyl-S-bromo-1-pentanol shown in the presence of mercury oxide and sulfuric acid.

(1952), and Feuer et al., J. Am. Chem. Soc, 77, 5740 (1955). 3,3-Dinitro-1-alkanol is produced by reaction of the corresponding primary amine with nitrous acid with the formation of unstable diazo compounds. In the decomposition of these diazo compounds, the desired alcohols are in addition to gaseous nitrogen obtain. A more detailed description can be found in Herzog et al. in J. Org. Chem., 23, 1809 (1958). Secondary nitro alcohols of this invention are produced by the selective reduction of ketones with sodium borohydride shown. The ketones are produced by the well-known Michael addition of alkyl vinyl ketones, such as methyl vinyl ketone, obtained from compounds with active hydrogen. The procedure is thorough described on p. 484 of "Advanced Organic Chemistry" by Fuson, John Wiley & Sons, Inc.

(1950).
It can be seen that within the framework of the above general

Application example 9

Preparation of propionaldehyde bis (7-aza-5,5,7-trinitro-3-octyl) acetal

Propionaldehyde - bis - (7 - aza - 5,5,7 - trinitro - 3 - octyl) acetal According to the formula described by the above examples, there is a great number and diversity benen method by reaction of 1-propylen-l-ol- of acetates by reaction of suitable starting materials can be represented by the above method. This new method can also be used for mixtures of unsaturated esters and nitro alcohols ver-35

caproic acid ester with 7-aza-5,5,7-trinitro-3-octanol in the presence of mercury sulfate and aluminum chloride shown.

and it is therefore within the scope of the invention to use acetals with mixed alkoxy groups to represent. For example, one can use an unsaturated ester of the tapped class, such as. B. vinyl acetate, with a mixture of nitro alcohols, e.g. B.

Acetaldehyde - bis - (2,2,2 - trinitroethyl) - acetal is a mixture of 2,2,2-trinitroethanol and 2-chloro the method described by the above examples ro-2-nitroethanol, react, with a reaction product arises which contains mixed alkoxy groups, e.g. B. Acetaldehyde ^^^ - trinitroethyl-2-chloro-2-nitroethyl acetal.

45 The reaction time is not critical for the implementation of the application example 11 new method. The only significant one

^ ,,, ,,,, -,., "" ,,. Effect of increasing or decreasing the temperature

Representation of acetaldehyde bis (2,2,4,4-tetrametric _{temperature consists in a corresponding} increase or

n-pentyl) acetal Reduction of the reaction rate. Even though

Acetaldehyde-bis- (2,2,4,4-tetranitro-n-pentyl) -acetal 50 the reaction temperature is not critical, it is over is for the sake of convenience and economy as described by the above examples preferable to use a temperature within 20 to 60 ° C for the practice of this invention.

Application example 10

Preparation of acetaldehyde bis (2,2,2-trinitroethyl) acetal

by reaction of vinyl heptanoate with 2,2,2-trinitroethanol in the presence of mercury acetate and zinc chloride.

Method by reacting vinyl isovalerate with 2,2,4,4-tetranitro-n-pentanol in the presence represented by mercury oxide and boron trifluoride etherate.

The ß-nitro alcohols used as the starting material in this invention are obtained by reacting the corresponding «-nitroalkanes with formaldehyde according to the well-known Henry reaction. the ß-geminal dinitro alcohols, such as 2,2-dinitroethanol, are preferably made by acidifying the corresponding alkali metal salts according to that of Duden and Pondorff in the Ber. 38, 2031 (1905). 2,2,4,4-tetranitrobutanol can by acidifying a salt of dinitroethanol. From the formed salt of 2,2,4,4-tetranitrobutanol the free alcohol is obtained by adding acid.

Claims (4)

PATENT CLAIMS: 1. Process for the preparation of nitroacetals of the general formula R-CH ₂ -C- NO ₅ --0-ACR ₅ characterized in that a carboxylic acid ester of an unsaturated alcohol of the general formula R ₁ O R-CH = COCR ₄ with a nitro alcohol of the general formula NO ₈ 2HO-ACR ₂ 10 is reacted in which R is a radical selected from the group of hydrogen and alkyl radicals; R _{1 is} a radical from the group consisting of hydrogen and alkyl radicals; R _{2 is} a radical from the group consisting of hydrogen, alkyl, halogen, nitroalkyl, nitro, aryl, alkylaryl, arylalkyl, cycloalkyl, haloalkyl and nitrozaalkyl radicals; R _{3 is} a radical selected from the group of hydrogen, alkyl, halogen, Nitroalkyl, nitro, aryl, alkylaryl, arylalkyl, cycloalkyl, haloalkyl and nitrozaalkyl radicals; R _{4 is} a radical selected from the group of hydrogen and alkyl radicals, and A is an alkylene radical. 2. The method according to claim 1, characterized in that the reaction in the presence of Mercury oxide and boron trifluoride etherate or of mercury oxide and sulfuric acid as a catalyst is performed. 3. Process according to Claims 1 and 2 for the preparation of acetaldehyde bis (2,2-dinitropropyl) acetal, characterized in that vinyl acetate with 2,2-dinitropropanol in the presence of Mercury oxide and boron trifluoride etherate is made to react. 4. Process according to Claims 1 and 2 for the preparation of acetaldehyde bis (2,2-dinitropropyl) acetal, characterized in that vinyl acetate with 2,2-dinitropropanol in the presence of Mercury oxide and sulfuric acid is reacted. © 309 669/322 8.63