BRIEFS Summary of papers published in this month's research quarterly, I@EC Product Research and Development
REACTIONS
OF ALPHA-OLEFINS
The reactions of a wide molecular weight range of a-olefins are reviewed and divided into two classes. Class I reactions are not affected by increased chain length of a-olefins. The high solubility of the reagents involved allows the olefin itself to be the medium for the 10 reactions listed. Experimental studies on the free-radical addition of HBr to a-olefins are described as an example of this class. Class I1 reactions show a marked decrease in reaction rate or yield with increased chain length of a-olefins. In this case, the reagents involved are not readily soluble in aolefins, especially olefins of higher molecular weight. For this class, yield and rate optimization studies of the free radical "4HSOa and the ionic addition of HzSOr to a-olefins are reported. The isomer distribution of the product alcohols from addition of HzSOd to dodecene is reported in detail.
RESOLUTIONS OF d/-2,3-DICHLORO-2-METHYLPROPlONIC ACID
Sodium 2,3-dichloro-2-methylpropionatehas been shown by McRae to be an effective gametocide. Since this biological activity is related to enzymatic action, it was of interest to resolve this compound into its optical isomers in order to determine the stereospecificity of its biological action. Resolution was accomplished by three bases-quinine, cinchonine, and d-a-methylbenzylamine. All three gave the levorotatory isomer of 2,3dichloro-2-methylpropionic acid, [ a ] 15 (methanol). The biological activity of the 1-isomer was nearly identical to the activity of the racemic acid.
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Charles E. Glassick and W. E. Adcock, Research Laboratories, Rokm Haas Co., Bristol, Pa. IND.ENG.CHEM.PROD.RES.DEVELOP. 3, 14-15 (1964)
E. Clippinper, California Research Corp., Richmond, Calif. IND.ENG.CHEM.PROD. RES.DEVELOP. 3, 3-7 (1964) SYNTHESIS OF PYRAZINES. ALKANOLAMINES
CYCLOAMINATION OF
Liquid- and vapor-phase continuous processes for converting isopropanolamine (1-amino-2-propanol) to 2,5-dimethylpyrazine and 2,5-dimethylpiperazine were investigated. A liquid-phase process employing a supported 6570 nickel catalyst resulted in a combined conversion to 2,5-dimethylpiperazine and 2'5-dimethylpyrazine of about 70%, but could not be controlled to give either product consistently as the major product. At low temperatures, while the catalyst was relatively fresh, 2,5-dimethylpiperazine was the major product; at higher temperatures and/or with older catalyst, 2,5-dimethylpyrazine was the major product. Several commercial fixed-bed catalysts were evaluated for converting isopropanolamine to 2,5-dimethylpyrazine. Copper chromite was selected for further study. A commercially feasible vapor-phase process based on copper chromite as the catalyst consistently gave about 65% conversion of isopropanolamine to 2,5-dimethylpyrazine and 10% to 2,5-dimethylpiperazine.
W. K. Langdon, W. W. Levis, Jr., D. R. Jackson, Moses Cenker, and G. E. Baxter, Wyandotte Chemicals Corp., Wyandotte, Mick.
PREPARATION OF SUBSTITUTED STYRENES BY CRACKING OF DIARYLETHANES
The synthesis of unsaturated compounds via vapor phase cracking of diarylalkanes is described. The feasibility of the method has been demonstrated with a wide variety of 1,l-diarylalkanes to give the corresponding substituted styrenes. I t is also an excellent route to a- and 8-methyl-substituted styrenes by cracking of 2,2and 1,l -diaryl-substituted propanes, respectively. Applicability in the preparation of butenes and cyclohexenes has been demonstrated. There is reason to expect that a wide variety of other aryl substituted olefins can be prepared by this route, but not highly negatively substituted styrenes. Side reactions involving dealkylation of side chains which themselves form fairly stable carbonium ions may be expected. Some data on isomer distribution are included, with a comparison of reported physical properties of the substituted styrenes.
E. M . Smolin, Ken Matsuda, and D. S. Hoffenberg, American Cyanamid Go., Stamford, Conn.
IND. ENG.CHEM.PROD.RES.DEVELOP. 3,16-19(1964)
IND.ENG.CHEM.PROD.RES. DEVELOP. 3,8-11 (1964) SYNTHESIS OF PYRAZINES. OF PIPERAZINES
VAPOR-PHASE DEHYDROGENATION
2-Methylpiperazine is dehydrogenated to methylpyrazine in 89 yo yield in a continuous vapor-phase process using a prereduced 80% Cu0:20% CrnOa catalyst at 350" C. The conversion to methylpyrazine initially is 85 to 87% and drops to approximately 5070 after 100 hours' operation. Activity of the catalyst can be restored by air oxidation and hydrogen reduction. Incorporation of alkaline or acidic materials in the catalyst results in a less effective catalyst. Increased feed rates tend to depress the conversion. Operation at moderate pressure allows the use of higher feed rates with high conversion. Piperazine, 2-ethylpiperazine, 2,6-dimethylpiperazine, and 2,3,5,6-tetramethylpiperazine are dehydrogenated to the corresponding pyrazines in conversions of 79 to 89% by the same process.
A NOVEL SYNTHESIS OF HIGHER ALUMINUM ALKYLS
Addition of diethylaluminum hydride to higher alpha-olefins gives alkyldiethylaluminum, which disproportionates to higher aluminum alkyls and triethylaluminum. Triethylaluminum is removed by use of a wiped-film distillation apparatus to yield higher aluminum alkyls. The product retains ca. 15 to 25 mole % (less than 10 weight yo)ethylaluminum groups. The method is economically superior to the diisobutylaluminum hydride method if by-product triethylaluminum values can be recovered and ethylaluminum groups in product can be tolerated.
C. M . Starks, D. D. Krehbiel, M . T. Atwood, and G. C. Feighner, Research and Development Defiartment, Continental Oil Co., Ponca City, Okla. IND.END.CHEM.PROD.RES. DEVELOP. 3, 19-20 (1964)
Moses Cenker, D. R. Jackson, W. K. Langdon, W. W. Levis, Jr., S. D. Tarailo, and G. E. Baxter, Wyandotte Chemicals Corp., Wyandotte, Mich.
IND.ENG.CHEM.PROD.RES.DEVELOP. 3,ll-14 (1964)
(Continued on page 83) VOL. 5 6
NO. 3
MARCH 1964
81
