Synthesis and reactions of trinitromethyl compounds

Tetrahedron, 1963, Vol. 19 Suppl.l, pp. 213 to 217. Pergamon Press Ltd.

SYNTHESIS AND REACTIONS OF TRINITROMETHYL COMPOUNDS 1 M. B. FRANKEL Stanford Research Institute, Menlo Park, California Abstract- Nitroform (trinitromethane) adds readily in a Michael type of addition to ct, ~­ unsaturated compounds such as acrylic acid and its esters, hydroxyrnethyl vinyl ketone, and nitroethylene. The synthesis of 2-nitro-3-acetoxy-1-propene and its unique reaction with 1,1dinitroethane and nitroform is described. 4,4,4-Trinitrobutyric acid was converted to 3,3,3trinitropropyl isocyanate and 3,3,3-trinitropropyl amine hydrochloride. Trinitromethyl carbamates were prepared by the addition of 2,2,2-trinitroethanol to various isocyanates and the addition of different alcohols to 3,3,3-trinitropropyl isocyanate. Trinitromethyl amines were prepared by the Mannich condensation of 2,2,2-trinitroethanol with various primary amines and the reaction of 3,3,3-trinitropropyl amine with nitroalcohols. All of these carbamates and secondary amines were converted to the corresponding N-nitro derivatives. The synthesis of trinitromethyl heterocyclic compounds and 2,2,2-trinitroethyl esters is also reported. .

preparation of trinitromethyl compounds is based on nitroform (trinitromethane) as the starting material. Severalmethods for the synthesis of nitroform appear in the older literature, but none were too satisfactory. Hantzsch and Rinckenberger- treated tetranitromethane, which was prepared from acetic anhydride and nitric acid, with alcoholic potassium hydroxide to obtain potassium nitroform which was then converted to free nitroform. Orton and Mckie" introduced acetylene into 100% nitric acid with mercuric nitrate catalyst and obtained nitroform. During World War II the method of Orton and McKie was developed to a pilot-plant scale by Schimmelschmidt- in the laboratory of 1. G. Farbenindustrie in Germany. For the first time a practical synthesis of nitroform was available, and it was now feasible to investigate the little known field of trinitromethyl chemistry. Schimmelschmidt conducted research on the addition of nitroform to organic compounds and found that nitroform added to iX, p-unsaturated carbonyl compounds and formaldehyde. THE

The work summarized in this paper was done by the Organic Research Group of the Aerojet-General Corporation, Azusa, California. A detailed series of papers covering this work will be published in the J. Org. Chern. and J. Chern. Engng, Data. 2 A. Hantzsch and K. Rinckenberger, s«. Dtsch. Chern. Ges. 32, 628 (1899). 3 K.J.Orton and P.V.McKie, J. Chern. Soc. 117,286 (1920). 4 K.SchiJrunelschmidt, Hunter Report, BIOS 1919/22 LG. July 3 (1946); Ger. Patent 852, 684, Oct. 16, (1952).

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In this same period Schenck et alo 5 in Germany investigated some of the reactions of 2,2,2-trinitroethanol. They prepared esters of 2,2,2-trinitroethanot and found that 2,2,2-trinitroethanol undergoes a Mannich condensation with ammonia and its derivatives. A systematic study of the synthesis of trinitromethyl compounds from nitrofonn and 2,2,2-trinitroethanol was initiated in 1947 at the Aerojet-General Laboratories, and a summary of this work is presented. The Michael addition of nitroform to iX, p-unsaturated compounds was first studied. It was found that nitroform added readily to acrylic acid, vinyl acrylate, allyl acrylate, hydroxymethyl vinyl ketone and nitro ethylene. The products are summarized in Table I. Of special interest was the addition of nitroform to 2-nitro-3-acetoxy-l-propene (I). The preparation of I is shown in the following equations:

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The aci sodium salt of 2-nitro-l, 3-propanediol was prepared by the condensation of nitromethane and formaldehyde. Acidification of the salt followed by acetylation gave 1,3-diacetoxy-2-nitropropane, which was then converted to 1. The conversion of the diacetate to the nitro olefin was initially carried out in fair yield by distillation at reduced 5

R.Schenck, Swedish Patent 148 217, Dec. 28 (1954); German Patent 937059, Dec. 29 (1955); U.S. Patent 2,731,460, Jan. 17 (1956); Swedish Patent 135832, May 27 (1952); British Patent 698138, Oct. 7 (1953); Swedish Patent 138456, Deco 23 (1952). 214

Synthesis and reactions of trinitromethyl compounds

pressure. Better yields were obtained using catalytic amounts of sodium acetate; however, the reaction was difficult to control when large amounts of ester were used. By far the best method was the vapor phase cleavage of the acetate ester. The initial work with I was carried out by studying its reaction with 1,1.dinitroethane, which reacts analogously to nitroform. It was expected that the addition would take place readily to yield 2,2,4-trinitro-1-acetoxy-pentane (II). A crystalline compound was isolated from this reaction. The elemental analyses values and molecular weight, however, were not in conformity with the expected compound C7HllNaOs (II) but were in agreement with the empirical formula C7HllNs010' Treatment of the new compound with potassium hydroxide gave the potassium salt, C7HlOKNsOlo.Bromination of this salt gave C 7HlOBrN 50 lO while nitration led to a compound with the empirical formula of C7Hl0N6012' The only compound to fit reasonably this data was 2,2,4,6,6-pentanitroheptane (III). The mechanism proposed for this reaction is shown below: N0 2

I

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I

N0 2

N0 2 N0 2

I

t

I

I

I

N0 2 N0 2

I

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+ CH 2=CCH20Ac - , CH aCCH2CCH20Ac ~..... CH aCCH2C=CH2

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N0 2

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The first step is undoubtedly the Michael addition of one mole of Ll-dinitroethane to I to form 2,4,4-trinitro-I-acetoxypentane (II). This compound having an active hydrogen on the p-carbon atom, can readily lose one mole of acetic acid to give 2,4,4-trinitro-1-pentene. The addition of a second mole of 1,1dinitroethane to the nitroolefin would then yield 2,2,4,6,6-pentanitroheptane (III). The first two products are transitory intermediates and were never isolated. The above mechanism is in agreement with the fact that the best yields of product were obtained when two moles of 1,1-dinitroethane were used for every mole of 1. In a similar manner the addition of nitroform to I gave 1,1,1,3,5,5,5-heptanitropentane (IV): N0 2 2(N02)aCH

+

I

N0 2 OH -

I

CH 2=CCHpAc - - - > (N°2)aCCH2CCH2C(N02h

I

H

I

IV 215

M.B.FRANKEL

It was of interest to determine the various types oftrinitromethyl compounds that could be prepared from 4,4,4-trinitrobutyric acid (V). Refluxing V with an excess of thionyl chloride gave the acid chloride (VI). Treatment of VI with sodium azide gave the corresponding azide which was converted in situ to 3,3,3-trinitropropyl isocyanate (VII). Hydrolysis of VII with hydrochloric acid gave 3,3,3-trinitropropyl amine hydrochloride (VIII). (N0 2)sCCH 2CH2C02H

SOCI', ,

(N0 2)sCCH2CH2COCI

V

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l

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~ (N02)8CCH2CH2NCO

HCI ,

(N0 2)sCCH2CH2NH2 . HCI

VII

VIII

The derivatives of 4,4,4-trinitrobutyric acid are summarized in Table 2. Compounds VII and VIII were used for the preparation of trinitromethyl carbamates and trinitromethyl amines, which are described in the following sections. TABLE

2. DERIVATIVES

Compound

[(N02)3CCH2CH2COhO a (N02)8CCH2CH2COCI a (N02)8CCH2CH2NCO (N0 2)sCCH2CH2NH 2 ' HCI

OF 4,4,4-TRINITROnUTYRIC ACID

% Yield

m.p,

b.p,

n15

65-66"/0'5 mm

1·4835 1'4805

109-110°

33 82 71'2 94

73-75°/10/t 161-163°

a Refluxing 4,4,4-trinitrobutyr~c acid with thionyl chloride for four hours gave 4,4,4trinitrobutyric anhydride while 4,4,4-trinitrobutyryl chloride was obtained after 20 hr of refluxing.

Trinitromethyl carbamates were prepared by the addition of 2,2,2-trinitroethanol to various isocyanates and the addition of different alcohols to 3,3,3trinitropropyl isocyanate. 2,2,2-Trinitroethanol is considerably more acidic than ordinary alcohols and thus reacts less readily with isocyanates. However, it was found that 2,2,2-trinitroethanol could be added to isocyanates provided that a suitable catalyst was used. The best catalyst for this purpose was ferric acetylacetonate (FeAA). Refluxing a chloroform solution of 2,2,2-trinitroethanol and an isocyanate for several hours in the presence of a catalytic amount of FeAA gave essentially quantitative yields of the carbamate. The trinitromethyl carbamates which were prepared are summarized in Table 3. All of these carbamates were nitrated to the corresponding N-nitro derivatives. Trinitromethyl amines were prepared by the Mannich condensation of 2,2,2trinitroethanol with various primary amines and the reaction of 3,3,3-trinitropropyl amine with nitroa1cohols. Since nitroalcohols are demethylolated 216

TABL E

Isocyanate

3.

POLY NITRO CARBAMATES AND N-NITROCARBAMATES

Carbamate

Alcohol

%Yield

m.p,

oil oil

CHaNCO

(N02)aCCH20H

CH aNHC02CH2CCN02)a

Quant

C2HsNCO

(N02)3CCH20H

C2HsNHC02CH2CCN003

Quant

~HP2CCH2NCO

(N02)3CCH20 H

C2Hs02CCH2NHC02CH2CCNO?)3

Quant

CHaN(NOz)CH2CH2NCO CHaCCN02)2CH2CH2NCO

(N0 2)aCCH1PH

CHaN(N02)CH2CH2NHC02CH2CCN00 a

Quant

CHaCCN02)2CH20H

CHaCCN002CH2CH2NHC02CH2CCN002CHa

Quant

71-72 98-99 oil oil oil

CHaCCN02)2CH2CH2NCO

(N02)aCCH20H

CHaC(N02)2CH2CH2NHC02CH2CCN02)a

Quant

CHaCCN02)2CH2N(N02)CH2NCO

(N02)~CCH20H

CHaCCN02)2CH2N(N02)CH2NHC02CH2CCN02)a

Quant

(N02)aCCH2CH2NCO

C2HsOH

(N0 2)aCCH2CH2NH C0 2C2Hs

(N02)aCCH2CH2NCO

CaHllOH

(N02)aCCH2CH2NHC02C6Hll

(N0 2hCCH2CH2NCO

CaHsOH

(N0 2)aCCH2CH2NHC0 2C6Hs

(N00 3CCH2CH2NCO

CHaCCN02)2CH20H

(N02hCCH2CH2NHC02CH2CCN002CHa

(N02)aCCH2CH2NCO

(N00aCCH20H

CHaCCNOz)2CH2CH2NCO

CCNOa)2- [CH 2OH h

CN02hCCH2CH2NHC02CH2CCN003 [CHaC(N02)2CH2CH2NHC02CHz12-CCN02)2

Quant

(N02)aCCH2CH2NCO

CCN0 2)2-[CH2OH12

[(N02)aCCH2CH2NHC02CH2h-CCN02)2

Quant

(N0 2hCCH2CH 2NCO

HOCH2C == CCH20H

[(N02)3CCH2CH2NHC02CH2Ch ==

Quant

oil oil

CH2[NCOh CCNOz)2-[CH 2CH2NC012

(N0 2hCH2OH

CH2[NHC0 2CH2CCN02)312

(N0 2hCCH2OH

CCN02)2-[CH2CH2NHC02CH2CCN02)3h

46'6 61'8

125-126 96-97

N(N02)-[CH2NCOh

(N02)aCCH20H

N(N02)-[CH2NHC02CH2CCN02)a12

Quant

oil

OCNCH 2N(N02)CH2CH2NCO

(N 0 2h CCH 2OH

(N 0 0 3CCH20 2CNH CH2N(N02) CH2CH2NH C0 2CH2CCN0 2)a

65- 67

N (N0 2) - [CH 2CH 2N COh [CH 2N(N02)CH2CH2NCOh

(N02 )3CCH20 H

N( N0 2)- [CH2CH2NH C0 2CH2CCN0 2)ah

86'7 92·5

(N0 2hCCH2OH

[CH2N(N02)CH2CH2NHC02CH2CCN02)ah

(N02)3CCH20 H

N(NOz)-[CH2CCN002CH2CH2NHC02CH2C(N02)ah

N(N02)-[CH2CCN002CH2CH2NCOh

49'2 40'6 63'7 91'7 81'7

65-66 96-97 102-103 103-104 91-92 128-129

N-Nitrocarbamate

% Yield

m.p,

[(N02)3CCH2CH2N(N02)C02CH2C]2 == CH2[N( N0 2)C0 2CH2CCN00a12 CCN02h-[CH2CH2N(N00C02CH2CCN02)ah

74'3 85'7 81'2 87'2 92-8 40'5 63'5 70'0 95'0 38'4 83'7 89'4 88'9 89'7 60'0 95'0 85-8

39-40 50-51 46-47 103-104 70-72 107-108 140-141 94-95 56-58 127-129 71-72 96-97 117-118 94-96 115-116 112-113 151-152

N(N02)-[CH2N(N02)C02CH2CCN02h12

CHaN(N02)C02CH2CCN00a C2HsN(N02)C02CH2CCN003 C2Hs02CCH2N(N02)C0 2CH2CCN02)3 CHaN(N00CH2CH2N(N00C02CH2CCN02)a CHaCCN002CH2CH2N(N02)C02CH2CCN02)2CHa CHaCCN02)2CH2CH2N(N00C02CH2CCN02)a CHaCCN02)2CH2N(N02)CH2N(N02)C02CH2C(N02)a (N02)aCCH2CH:iN(N02)C02C2Hs (N02)aCCH2CH2N(N02)C02C6Hll (N02)aCCH2CH2N(N02)C02C6H4N02 (N02)aCCH2CH2N(N00C02CH2CCN02)2CHa (N02hCCH2CH2N(N00C02CH2CCN02)a [CHaCCN02)2CH2CH2N(N00C02CH2h-CCN02)2 [(N02hCCH2CH2NCN02)C02CH212-CCN02)2

62'3

185-186

(N 02)3CCH202CN(N02)CH2N(N00CH2CH2N(N02)C02CH2CCN02)3

62-8

130-131

N(N02)-[CH2CH2N(N00C02CH2CCN00ah

86'3

113-114 120-122

85'7

156-158

[CH2N(N0 2)CH2CH2N(N0 0 C0 2CH2CCN 0 2)a]2

87-8

127-128

91'3

157-159

N(N02)-[CH2CCN02)2CH2CH2N(N02)C02CH2CCN02)3h

93'3

150-151

Synthesis and reactions of trinitromethyl compounds

in the presence of base, the condensations were carried out by adding portionwise an equivalent amount of base to an aqueous solution of the amine hydrochloride and the nitroalcohol. The product immediately separated from the aqueous solution. The trinitromethyl amines that were prepared are summarized in Table 4. All of these secondary amines were nitrated to the corresponding nitramines, The reaction of 2,2-dinitro-l,3-propanediol with 3,3,3-trinitropropylamine and formaldehyde gave a 40·8 % yield of 1,3-bis(3',3',3'-trinitropropyl)-5,5-dinitroperhydropyrimidine, m.p. 119-121°. The condensation of 3,3,3-trinitropropylamine with formaldehyde gave a quantitative yield of 1,3,5-tris-(3', 3', 3'-trinitropropyl)-perhydro1,3,5-triazine, m.p, 121-123°. A series of 2,2,2-trinitroethyl esters were prepared according to the procedure of Hill, 6 by treating the acid chlorides with 2,2,2-trinitroethanol in the presence of a catalytic amount of aluminium chloride. 4,4,6,6,8,8hexanitroundecanedioic acid was esterified with 2,2,2-trinitroethanol using 100% sulfuric acid as the ionizing solvent. The results are summarized in Table 5. ~cknowledgement

- We are indebted to the Office of Naval Research for the financial support of this work.

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