Chemical Agents

This invention relates to the synthesis of new toxic chemical compounds which are useful as chemical warfare agents. More particularly, our invention is concerned with novel compounds produced by means of a quaternizing reaction.

The chemical agents act mostly on the peripheral cholinergic nervous system which includes the motor nerves, the proganglionic fibers, the ganglia, the postganglionic parasympathetic fibers, and neuromuscular functions. The transmission of impulses along a nerve or from nerve fibers to muscle fibers or secretory coils or from one nerve fiber to another across synapses in ganglia is thought to involve chemical changes either directly or as the source of potential differences.

Quaternary ammonium compounds in general are known to be physiologically active materials. Mainly because of their positively charged "onium" centers they are attracted by anionic sites in animal tissues, particularly those situated at cell surfaces and interfaces. They can induce physiological responses that mimic or antagonize the action of acetylcholine as a result of their interaction with the various physiological receptor sites of acetylcholine, especially those at membranes of muscle cells. They also combine with enzymes such as acetylcholinesterase, other esterases, acetylcholineacetylase, etc., thus inhibiting their participation in the biological processes.

One of the significant anatomical differences between the neuromuscular junctions and other acetylcholine receptive sites is the absence of a membrane barrier or a sheath such as envelops the ganglia. The comparative case of accessibility of the neuromuscular junctions to "onium" compounds contributes to their relatively fast onset of action and partly explains why in many instances relatively small doses suffice to evoke physiological actions that modify or interrupt normal neuromuscular impulse transmission.

Depending on their chemical structures different quaternary compounds interfere with the mechanism of impulse transmission in different manners and the final physiological effects can vary considerably. Some quaternary ammonium compounds are used as therapeutic agents, others are known to be lethal. The magnitude, accessibility, and distribution of the positive charges in quaternary compounds are believed to be the key factors in the determination of specificity of action. Recognition of these facts explains the strikingly different physiological behavior so often observed when structurally very closely related compounds are compared. The nature of the groups attached to the quaternary nitrogens influences the distribution of the cationic charges. The length and branching of aliphatic chains and the volume and configuration of aromatic and alicyclic rings have a bearing on the ease or difficulty of approach to the specific receptor sites. Electrophilic and nucleophilic centers in the molecule will insert their inductive effects on the positive charges and can also aid in the interaction with the "esteratic sites" of various enzymes. These sites are believed to be located in close vicinity to the anionic sites of the active centers. Substitution of different functional groups influence association and hydration and may considerably change the solubilities in physiological media. In bis-quaternary and polyquaternary compounds, the distance between the electric charges must be considered. These factors contribute to govern the rate and reversibility of the chemical reactions involved, and contribute to determine the final physiological responses.

Our chemical agents interfere with the normal process of neuromuscular impulse transmission and thus disrupt the propagation of impulses from nerves to muscles. We have also found these compounds to be extremely toxic at relatively low dose levels in various animals.

The object of this invention is to synthesize new lethal agents useful in chemical warfare in high yields wherein said products are well suited for industrial scale manufacture.

Our compounds may be employed in any munition suitable for handling a relatively non-volatile toxic agent such as bombs, shells, spray tanks, rockets, missiles, aerosol generators, and others.

Other objects of and uses for the invention will in part be obvious and will in part appear hereinafter in the following detailed description thereof.

In accordance with our invention the tertiary function of a tertiary aminoester was quaternized with N-(10-bromodecyl)-N-(3-dimethylcarbamoxy-.alpha.-picolinyl)-N,N-dimethylam monium bromide under reflux conditions in a solvent such as acetonitrile. Reflux was maintained for 9-24 hours. The solvent was then evaporated, the oily residue stirred in boiling acetone or ethyl acetate, and the solvent decanted. The remaining gummy material was dissolved in a solvent such as acetonitrile or chloroform and the solution treated with decolorizing charcoal. The purified solution was concentrated to a few milliliters and the concentrate evaporated under reduced pressure. The solid material that remained constitutes new compounds of the present invention which may be represented by the following generic formula: ##STR2##

wherein x is one equivalent of a monovalent or polyvalent anion; R and R' are methyl or ethyl radicals; R.sub.1, R.sub.1 ', R.sub.2, R.sub.2 ' are hydrogen or a methyl radical; and Z is a radical selected from the group consisting of methyl, ethyl, propyl, butyl, and pentyl.

The procedure used for the preparation of the new toxic materials is schematically shown below: ##STR3##

wherein X is a halide ion, preferably bromide; R, R', R.sub.1, R.sub.1 ', R.sub.2, R.sub.2 ', and Z as defined above.

If compounds are desired in which X is other than a halide ion, the above quaternary compounds are treated with the desired acid by simple exchange reactions as set forth below.

N-(10-bromodecyl)-N-(3-dimethylcarbamoxy-.alpha.-picolinyl)-N,N-dimethylamm onium bromide (1.05 g) and .beta.-dimethylaminoisopropyl acetate (0.73 g) were dissolved in about 10 ml of acetonitrile and the solution was refluxed for about 9 hours. The solution was concentrated to about 3-4 ml and on addition of ethyl acetate a viscous oily material separated. The solvent was decanted and the remaining gummy material was dissolved in acetonitrile and treated with decolorizing charcoal. After the charcoal was removed by filtration the filtrate was concentrated at normal pressure to a few milliliters and the concentrate placed in an apparatus which was kept under reduced pressure (about 1 mm) at room temperature overnight. Thus, 1 g of the product, 1-[N,N-dimethyl-N-(2-acetoxy-2-methylethyl)ammonio]-10-[N-(3-dimethylcarba moxy-.alpha.-picolinyl)-N,N-dimethylammonio]decane dibromide, was obtained as a white deliquescent solid. Because of its deliquescency a sample of the compound was converted to and analyzed as the tetraphenylboronate salt. The dibromide salt was dissolved in water and to this solution an aqueous solution of sodium tetraphenylboron (in molar excess) was added. The solid that formed was separated by filtration, washed a few times with water and then dried, m.p. 65.degree.-67.degree. C.

Analysis for C.sub.76 H.sub.92 B.sub.2 N.sub.4 O.sub.4 Calcd: C, 79.6; H, 8.1; N, 4.9. Found: C, 79.5; H, 8.2; N, 4.9.

N-(10-bromodecyl)-N-(3-dimethylcarbamoxy-.alpha.-picolinyl)-N,N-dimethylamm onium dibromide (1.05 g) and .beta.-dimethylaminoethyl butyrate (0.8 g) were dissolved in 10 ml of acetonitrile and refluxed for 24 hours. The mixture was allowed to cool to room temperature and upon addition of acetone (50 ml) an oily material separated. The solvent was decanted and the remaining viscous oil stirred in about 50 ml of boiling acetone for 10 minutes after which time the acetone was decanted. The gummy residue was dissolved in chloroform and treated with decolorizing charcoal. After the charcoal was removed by filtration the filtrate was concentrated at normal pressure to a few milliliters and the concentrate placed for 4 hours in an apparatus which was kept under reduced pressure (about 1 mm) at about 78.degree. C. Thus, about 0.95 g of the product, 1-[N,N-dimethyl-N-(2-butyroxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.al pha.-picolinyl-N,N-dimethylammonio]decane dibromide, was obtained as a white hygroscopic solid.

Analysis for C.sub.29 H.sub.54 N.sub.4 O.sub.4 Br.sub.2 Calcd: C, 51.0; H, 8.0; Br, 23.4. Found: C, 50.9; H, 8.1; Br, 22.8.

A solution of 62.3 g of 2-dimethylaminomethyl-3-dimethylcarbamoxypyridine and 251 g of 1,10 dibromodecane was refluxed for about 7 days in 1 liter of anhydrous ether. The product that formed was collected on a filter, washed with two 100 ml. portions of anhydrous ether, and dissolved in 1 liter of acetone. The acetone solution was treated with decolorizing carbon and filtered. The filtrate was concentrated under reduced pressure to approximately 200 ml. Ether was added until the solution became turbid. The mixture was then sealed and chilled overnight. The resultant crystalline product was collected and further purified by recrystallization from ethyl acetate. The pure product was dried in vacuo for 2 hours, yielding 76 g of material, m.p. 90.degree.-92.degree. C.

Analysis for C.sub.21 H.sub.37 Br.sub.2 N.sub.3 O.sub.2 Calcd: C, 48.2; H, 7.1; Br.sup.- (ionic), 15.3; O, 6.1. Found: C, 48.2; H, 7.0; Br.sup.- (ionic), 15.2; O, 6.2.

The compounds that are representative of our invention are listed below by name and chemical structure.

1-[N,N-dimethyl-N-(2-acetoxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.alph a.-picolinyl)-N,N-dimethylammonio]decane dibromide. ##STR4##

1-[N,N-dimethyl-N-(2-acetoxy-2-methylethyl)ammonio]-10-[N-(3-dimethylcarbam oxy-.alpha.-picolinyl)-N,N-dimethylammonio]decane dibromide. ##STR5##

1-[N,N-dimethyl-N-(1-methyl-2-acetoxyethyl)ammonio]-10-[N-(3-dimethylcarbam oxy-.alpha.-picolinyl)-N,N-dimethylammonio]decane dibromide. ##STR6##

1-[N,N-diethyl-N-(2-acetoxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.alpha .-picolinyl)-N,N-dimethylammonio]decane dibromide. ##STR7##

1-[N,N-dimethyl-N-(2-propionoxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.a lpha.-picolinyl)-N,N-dimethylammonio]decane dibromide. ##STR8##

1-[N,N-diethyl-N-(2-propionoxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.al pha.-picolinyl)-N,N-dimethylammonio]decane dibromide. ##STR9##

1-[N-methyl-N-ethyl-N-(2-propionoxyethyl)ammonio]-10-[N-(3-dimethylcarbamox y-.alpha.-picolinyl)-N,N-dimethylammonio]decane dibromide. ##STR10##

1-[N,N-dimethyl-N-(2-butyroxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.alp ha.-picolinyl)-N,N-dimethylammonio]decane dibromide. ##STR11##

1-[N,N-dimethyl-N-(2-valeroxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.alp ha.-picolinyl)-N,N-dimethylammonio]decane dibromide. ##STR12##

1-[N,N-dimethyl-N-(2-caproxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.alph a.-picolinyl)-N,N-dimethylammonio]decane dibromide. ##STR13##

We have shown preferred compounds in which the anion is limited to the halogen moiety, in particular the bromide, since the bromoalkanes are good quaternizing agents. In general, however, it is only necessary that the anions merely have to meet the requirement of being capable of forming a stable salt with the quaternary nitrogen. Thus the halogen ions can be exchanged with other anions of relatively strong monovalent or polyvalent acid by conventional methods. For example, if X.sup.- is a bromide in the final product, a solution of the compound can be treated with a basic ion exchange resin or mixed with silver oxide and subsequently the desired acid is added to the quaternary hydroxide solution. Anions other than the halogens may also be obtained by metathesis with the halide form of the quaternary ammonium compound. Suitable as representations of X.sup.- are the anions hydrogen oxalate, perchlorate, nitrate, tetraphenylboronate, and hydrogen sulfate. Representative examples of these additional endproducts are:

1-[N,N-dimethyl-N-(2-butyroxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.alp ha.-picolinyl)-N,N-dimethylammonio]decane di(hydrogen oxalate).

1-[N,N-dimethyl-N-(2-butyroxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.alp ha.-picolinyl)-N,N-dimethylammonio]decane diperchlorate.

1-[N,N-dimethyl-N-(2-butyroxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.alp ha.-picolinyl)-N,N-dimethylammonio]decane dinitrate.

1-[N,N-dimethyl-N-(2-butyroxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.alp ha.-picolinyl)-N,N-dimethylammonio]decane di(tetraphenylboronate).

1-[N,N-dimethyl-N-(2-butyroxyethyl)ammonio]-10-[N-(3-dimethylcarbamoxy-.alp ha.-picolinyl)-N,N-dimethylammonio]decane di(hydrogen sulfate).