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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a new synthesis for sulfonyl semicarbazides (sulfonyldiazanecarboxamides) and sulfonyl-1,2-diazanediacarboxyamide which are a class of thermally labile compounds some currently finding use as blowing agents.
2. Description of the Prior Art
Sulfonyl semicarbazides are presently produced by reacting the corresponding sulfonyl hydrazide with a source of cyanic acid as exemplified in U.S. Pat. No. 3,152,176-Hunter. Another method for synthesizing sulfonyl semicarbazides is disclosed in assignee's copending application Ser. No. 490,039, filing date July 19, 1974, entitled A Method for Producing Sulfonyl Semicarbazides by John E. Herweh.
SUMMARY OF THE INVENTION
The process involved is the reaction of sulfinic acid salts with alpha-carbonyl azo compounds in particular with 1,1' azobisformamide and other substituted 1,2-diazenecarboxamides. The yields of the sulfonyl semicarbazides are high, in some cases essentially quantitative, and offer economical advantages over presently used preparatory routes for which the yields described in the literature are considerably smaller.
According to this invention there is provided a process for the manufacture of sulfonyl dicarboxamides of the formula ##STR1## wherein R and R' may be the same or different and are C.sub.1 to C.sub.8 alkylamino, di C.sub.1 to C.sub.8 alkylamino, phenylamino, diphenylamino, C.sub.1 to C.sub.8 alkyl substituted phenylamino, di C.sub.1 to C.sub.8 alkyl substituted phenylamino, naphthylamino or dinaphthylamino; R" is selected from the group consisting of C.sub.1 to C.sub.8 alkyl, phenyl, C.sub.1 to C.sub.8 alkyl substituted phenyl and naphthyl, which comprises reacting either in water or in an inert aprotic dipolar solvent a diazenedicarboxamide of the formula R'CN.dbd.NCR with an organosulfinic acid salt of the formula R"SO.sub.2 M wherein R, R' and R" is defined above and M is potassium, sodium, zinc or ammonium and recovering the sulfonyl dicarboxamide.
Also, according to this invention there is provided sulfonyl dicarboxamides of the formula ##STR2## wherein R and R' are the same or different and are selected from the group consisting of C.sub.1 to C.sub.8 alkylamino, di C.sub.1 to C.sub.8 alkylamino, phenylamino, diphenylamino, C.sub.1 to C.sub.8 alkyl substituted phenylamino, naphthylamino, and dinaphthylamino; and R" is selected from the group consisting of C.sub.1 to C.sub.8 alkyl, phenyl, C.sub.1 to C.sub.8 alkyl substituted phenyl and naphthyl.
DESCRIPTION OF THE PREFERRED EMBODIMENT
When dimethyl sulfoxide solutions of equimolar amounts of 1,1' azobisformamide or other 1,2-diazenecarboxamides and zinc, sodium, potassium or ammonium salts of organosulfinic acids are combined at room temperature, an immediate reaction occurs, as evidenced by the rapid disappearance of the yellow-orange color associated with diazenedicarboxamide. Addition of the reaction mixtures to water causes the corresponding sulfonyldiazanecarboxamides and sulfonyl-1,2-diazanedicarboxyamide (sulfonyl semicarbazides) to precipitate as white solids in high yields and in a relative pure state. It should be noted that hereafter the term sulfonyl semicarbazides will be referred to in the more generally acceptable nomenclature as sulfonyldiazane carboxamides. Similarly, the older term sulfonyl-1,2-hydrazodicarboxamide is hereinafter referred to as the sulfonyl-1,2-diazanedicarboxamide. This reaction is greatly facilitated by solvation of the particular metal cation of the sulfinate salt in dimethyl sulfoxide or other similar dipolar aprotic solvent.
The reaction of 1,2-substituted diazenedicarboxamides with salts of organic sulfinic and may be expressed by the following general formula: ##STR3## where R" signifies C.sub.1 to C.sub.8 alkyl, phenyl, C.sub.1 to C.sub.8 alkyl substituted phenyl or naphthyl, M is selected from the group consistng of zinc, sodium, potassium or ammonium, R and R' are the same or different and are NH.sub.2, C.sub.1 to C.sub.8 alkylamino, di C.sub.1 to C.sub.8 alkylamino, phenylamino, diphenylamino, substituted phenylamino, di substituted diphenylamino, naphthyl amino or dinaphthylamino.
Examples of 1,2-diazenedicarboxamides which can be used for the purpose of this invention are:
1,1' azobisformamide (1,2-diazenedicarboxamide)
N,n-dimethyl 1,2 diazenedicarboxamide
N,n-diethyl 1,2 diazenedicarboxamide
N,n-dipropyl 1,2-diazenedicarboxamide
N,n-dibutyl 1,2-diazenedicarboxamide
N,n-dioctyl 1,2-diazenedicarboxamide
N,n-diphenyl 1,2-diazenedicarboxamide
N,n-di(4-methylphenyl) 1,2-diazenedicarboxamide
N,n'-dimethyl-1,2-diazenedicarboxamide
N,n'-diethyl-1,2-diazenedicarboxamide
N,n'-dibutyl-1,2-diazenedicarboxamide
N,n'-dioctyl-1,2-diazenedicarboxamide
N,n'-diphenyl-1,2-diazenedicarboxamide
N,n'-di(4-methylphenyl)-1,2-diazenedicarboxamide
N,n'-dinaphthyl-1,2-diazenedicarboxamide
The organosulfinic acid salt will have the formula R"SO.sub.2 M where R" is alkyl having from 1 to 8 carbon atoms, phenyl, lower alkyl substituted phenyl, or naphthyl, and M is zinc, sodium, potassium or ammonium.
Examples of sulfinic acid salts which can be used for the purpose of this invention are:
zinc bis (p-toluenesulfinate)
zinc bis (benzenesulfinate)
sodium p-toluenesulfinate
sodium benzenesulfinate
ammonium p-toluenesulfinate
zinc dipentanesulfinate
potassium xylenesulfinate
The reactions are carried out in dipolar aprotic solvents inert to the starting ingredients. The role of such solvent is to dissolve, at least in part, one or more of the reactants without effecting any change in chemical composition of the reactant species. Solvents of this type found useful in this invention include tetrahydrothiophene 1,1-dioxide, tetramethyl urea, hexamethyl phosphoryl triamide, dimethyl sulfoxide, dimethylformamide and the like. Mixtures of these solvents are also useful in reacting this invention. The two most commonly used are dimethylsulfoxide and dimethylformamide. The former is the most preferred dipolar aprotic solvent for use in these reactions.
Water may also be used in these systems when it does not react with either of the two reactants and dissolves at least in part one of them. For instance, a water suspension of 1,1' azobisformamide can be reacted with a water solution of sodium benzenesulfinate or sodium p toluenesulfinate which results in an alkaline reaction mixture that requires neutralization to completely separate out the sulfonyl semicarbazide. Similarly, when a dipolar aprotic solvent suspension of substituted 1,2-diazenedicarboxamide is reacted with a dipolar aprotic solvent solution of sodium p-toluenesulfinate, neutralization of the resulting alkaline reaction mixture is required to recover the sulfonyl semicarbazide completely.
The reaction should be carried out in a temperature range from approximately 20.degree. C. to 80.degree. C. and preferably in the range of 45.degree. C. to 50.degree. C. when water is the solvent of choice, and 25.degree. C. to 35.degree. C. when an aprotic solvent is used.
The concentration of the reactants in the inert solvent should be in the range of 5% to 50% by weight of the solvent and preferably in the range of from 8% to 12% by weight of the solvent when water is used and from 5% to 50% by weight when an aprotic solvent is utilized. Generally, the concentration of the reactant will depend on the so of the reactant in the solvent.
The reaction may be carried out in any convenient manner utilizing suitable vessels or containers. One of the outstanding advantages of the present process is its simplicity, requiring mere mixing of the reactive solutions, and separating out the product.
In many cases the yields of sulfonyl semicarbazides are near quantitative and the materials are analytically pure after appropriate washing and drying.
The following examples illustrate several embodiments of the invention.
EXAMPLE 1
General Procedure for Reaction of 1,2-diazenedicarboxamides with Metal Organosulfinates in Dimethyl Sulfoxide
1,2-diazenedicarboxamide (e.g. 1,1' azobisformamide, 0.01 mol) and the metal organosulfinate (molar amount depending on metal cation) are dissolved in a suitable amount of dimethyl sulfoxide (typically 25 ml per 0.01 mol for both 1,1' azobisformamide and the sulfinate). When the two solutions are combined, the yellow to orange color due to 1,2-diazenedicarboxamide fades almost immediately. The color is usually completely discharged after several minutes. Typically, the reaction mixture is left at room temperature overnight prior to workup.
The relatively clear, colorless reaction mixture is added to excess water (about 300 ml per 50 ml of reaction mixture) and cooled to ice both temperatures. The white solid precipitate is filtered, washed with fresh cold water and dried in a vacuum (in presence of P.sub.2 O.sub.5).
The procedure followed when dimethyl formamide is used, as the solvent is identical to that described above.
The results from a number of reactions are summarized in the following table:
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Reaction of 1,2-diazenedicarboxamide (0.01 Mol) with Metal
Organosulfinates in Dipolar Aprotic Solvents
Sulfonyl-
diazane-
Metal Reaction carboxamide
Organo- Time, Solvent.sup.a %
sulfinte Mol Minutes (ml) Mol Yield
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Dimethyl
Sulfoxide
Zn bis Approx.
(p-toluene-
.005 3 min. 65.sup.b
.0088 88
sulfinate)
Zn bis Approx.
(p-toluene-
.005 3 min. 50 .0090 90
sulfinate)
Zn bis Approx.
(benzene-
.005 3 min. 50 .0086 86
sulfinate).sup.c
Na Approx.
p-toluene-
.01 3 min. 40 .0081 81
sulfinate
Dimethyl
Formamide
Zn bis Approx.
(benzene-
.005 3 min. 75 .0079 79
sulfinate)
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.sup.a Total volume
.sup.b t-butyl alcohol (20 ml) also present
.sup.c Dihydrate
EXAMPLE 2
General Procedure for Reaction of 1,2-diazenedicarboxamides with Metal Organosulfinates in Water
A solution of sodium organosulfinate (0.05 mol) in 50 ml of water is added rapidly to a stirred suspension of 1,1' azobisformamide (0.05 mol) in 100 ml of water. No apparent reaction occurs and the reaction mixture is quickly heated to 45.degree. C. to 50.degree. C.
The reaction mixture is maintained at 45.degree. C. to 50.degree. C. for a varied period of time until the suspended solid phase became white. After cooling to room temperature, the alkaline reaction mixture is neutralized with 3N hydrochloric acid and the filer-cake is washed thoroughly with water and dried in a vacuum (in presence of P.sub.2 O.sub.5). The reaction product was identified as sulfonyl diazanecarboxamides by elemental analysis, molecular weight, melting point, infrared and nuclear magnetic resonance spectroscopy.
The results from a number of reactions are summarized in the following table:
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Reaction of 1,1'Azobisformamide (0.05 Mol) with
Sodium Organosulfinates (0.05 Mol) in Water
Sulfonyl
Reaction
Semicarbazide
Sodium Time, %
No. Organosulfinate
Minutes Mol Yield
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1 benzenesulfinate
90 .046 92
2 p-toluenesulfinate
75 .049 98
3 p-toluenesulfinate
45 .050 99
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EXAMPLE 3
General Procedure for the Reaction of Substituted Diazenedicarboxamides with Metal Organosulfinates
The substituted diazenedicarboxamides (0.01 mol), dissolved in 25 ml of Me.sub.2 SO, were combined with solutions of the sulfinate (0.01 mol) in 25 ml of Me.sub.2 SO and the reaction mixtures were worked up in a manner similar to that described for 1,2-diazenedicarboxamide (Example 1). Addition of the reaction mixtures to water gave weakly basic solutions. In the case of the N,N'-diethyl- and N,N,N',N'-tetramethyldiazenedicarboxamides the basic solutions remained clear, but solid reaction products precipitated upon acidification (see the following table). When added to water, reaction mixtures containing the substituted N-phenyl derivatives gave milky basic reaction mixtures; acidifications gave the products shown in the table.
In the case of N,N'-diphenyl-1,2-diazenedicarboxamide the crude reaction product was resolved into its two components by treatment with cold aqueous 5% sodium hydroxide. 1-p-toluenesulfonyl-N,N-diphenyl-1,2-diazanedicarboxamide is insoluble in the cold alkali and can be purified by repeated recrystallization from benzene. The aqueous alkali solubles were acidified to precipitate the I component; repeated recrystallization from acetic acid afforded analytically pure product.
The results obtained from these reactions are summarized below. ##STR4## where R"SO.sub.2 M = sodium p-toluene sulfinate
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Product
R' R Type.sup.a
% Yield
MP.degree. C.
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EtNH EtNH II 39 199-200.degree. DEC.sup.b
Me.sub.2 N
Me.sub.2 N
I 77 197-198.degree. DEC.sup.c
H.sub.2 N
Ph.sub.2 N
II 98 186-188.degree. DEC.sup.d
PhN PhN I & II 33 & 27
180-182.5 DEC &
210-211 DEC
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.sup.a Satisfactory elemental analyses and molecular weight determination
were recorded for all compounds.
.sup.b Recrystallized from chloroform
.sup.c Recrystallized from 1:4 carbon tetrachloride:chloroform
.sup.d Recrystallized from abs. alcohol
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