Pyrrolinium iodide

Ethyl-2-methyl-3-(10,11) -dihydro-5H-dibenzo [a,d] cycloheptene-5-ylidene)-1 -pyrrolinium iodide (4.7 g) was dissolved in 7 cc of methanol. To this solution there were added 1.4 g of sodium boron hydride within about 80 minutes with stirring and stirring of the solution was continued for two hours to complete the reaction. The reaction mixture was acidified with 10% aqueous hydrochloric acid solution and then the methanol was distilled off. The residual solution was alkalized with 20% aqueous sodium hydroxide solution and extracted with ether. The ether layer was dried over magnesium sulfate and the ether was distilled off. The resulting residue was further distilled under reduced pressure to yield 2.0 g of 1-ethyl-2-methyl-3-(10,11 ) dihydro-5H-dibenzo[a,d]cycloheptene-5-ylidene)pyrrolidine (boiling point 167°C/4 mm Hg.). 

B. 2-Methylmercapto-N-methyl-A l-pyrrolinium iodide. N-MethyI-2-pyrrolidinethione (310 g., 2.69 moles) is dissolved with stirring in 1.1 1. of anhydrous ether in a 2-1. three-necked flask equipped with a mechanical stirrer, a reflux condenser fitted with a drying tube, and a dropping funnel. To this solution is added ca. 5 g. of the product as seed crystals (Note 4) to prevent initial deposition of the iodide as an oil that suddenly crystallizes with considerable evolution of heat. Methyl iodide (520 g., 3.66 moles) is then added rather rapidly. The solution becomes turbid after a short time, and separation of the salt begins with heat evolution. After 12 hours the hygroscopic, crystalline paste is filtered and dried in a desiccator yield 663 g. (96%). 

C. 2-Methylmercapto-N-methyl-A 2-pyrroline. 2-MethyImer-capto-N-methyl-A -pyrrolinium iodide (662 g., 2.57 moles) is suspended in 1.25 1. of anhydrous ether in a 4-1. three-necked flask equipped with a mechanical stirrer and a reflux condenser with a segment-shaped paddle. Potassium f-butoxide (448 g., 4.0 moles) is added in one batch to this suspension with vigorous stirring. The mixture warms up a little, and later the solid becomes fine-grained and more mobile as a result of separation of potassium iodide. After being stirred for 1.5 hours at room temperature, the mixture is treated with 1.81. of anhydrous ether and boiled under reflux on a water bath for 5 hours. 

The method described for the preparation of 2-methylmercapto-N-methyl-A -pyrrolinium iodide is based on the general procedure of several authors.2,7-9 Its preparation has not been described previously the corresponding methyl sulfate has been obtained as a noncrystalline, viscous mass.4,10... 

To 3.8 g of 2-methyl-3-(10,ll-dihydro-5H-dibenzo[a,d]cycloheptene-5-ylidene)-l-pyrroline, there were added 8 g of ethyl iodide. This mixture was placed into a closed vessel and heated at 80°C in a water-bath for one hour. After completing the reaction, the reaction mixture was cooled and the unreacted ethyl iodide was distilled off to yield 5.5 g of l-ethyl-2methyl-3-(10,ll-dihydro-5H-dibenzo[a,d]cycloheptene-5-ylidene)-l-pyrrolinium iodide in the form of yellow crystals. These crystals were recrystallized from a mixture of acetone and ether to yield yellow needles of the melting point 223°C. 

Cyclocondensation of l,4-diarylpyridazino[4,5-d]pyridazines with a ketene A,5-acetal, generated in situ by treatment of 2-methylthiol-l -methyl- 1-pyrrolinium iodide with DBU, proceeded smoothly... 

A pyrrolinium iodide has been obtained via the reaction of 2-methyl-2-alkynyl-oxirane with dimethylhydrazine (e.g., Eq. 203). ... 

Although several systems have been evaluated to determine the structure of the ring formed in cyclopolymerization, very little work has been reported on the original cyclopolymer reported by Butler ( 7) that was obtained from N,N-dimethyldiallyl-ammonium bromide or the chloride. Consequently, we undertook a study of a five-membered quaternary ammonium polymer, poly(l,l, 3,4-tetramethyl-3-pyrrolinium bromide) as a model system. N,N-dimethyl-3,4-dimethylenepyrrolidinium bromide (6 ) was prepared by reacting dimethylamine with 2,3-bis(bromomethyl)-l,3-butadiene (5). In addition to the bromide salt (6), the iodide salt was also prepared by reacting 2,3-bis(bromomethyl)-l,3-butadiene... 

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