| [Visitor (113.218.*.*)]answers [Chinese ] | Time :2024-01-19 | | Human arithmetic uses the decimal system, which may have something to do with the fact that humans have ten fingers. Aristotle claimed that the universal use of the decimal system is simply the result of the anatomical fact that the vast majority of people are born with 10 fingers. In fact, in the written notation system independently developed in the ancient world, almost all of them were decimal except for the wedge-shaped numerals of the Babylonian civilization, which had a decimal system, and the Mayan numerals, which had a base of 20. However, these decimal notation systems are not bit-based. |
| [Visitor (113.218.*.*)]answers [Chinese ] | Time :2024-01-19 |  Undecylenal
【Structure or Molecular Formula】
[Relative molecular weight or atomic weight] 168.28
【Density】0.8496(20°C)
[Melting point (°C)]7
【Boiling Point(°C)】235;103(1.333E3Pa)
【Flash Point(°C)】100;92(Closed)
[refractive index] 1.4427
【Character】
Colorless to light yellow oily liquid, with a greasy smell when thick, and a strong rose and citrus aroma after dilution.
【Dissolution】
Almost insoluble in water and glycerol, soluble in ethanol, propylene glycol and most organic solvents.
【Applications】
Spices, preparation of citrus fruity flavors, used in food, preparation of rose, lily of the valley and other floral flavors, used in cosmetics, polymerization monomers.
【Preparation or Source】
(1) Ethyl undecylenate is used as raw material, reduced to undecylenol with sodium metal, and then oxidized with dichromatic acid (or dehydrogenated with cuprous); (2) Undecynoyl chloride is dissolved in benzene, and lead-barium sulfate is used as a catalyst for hydrogenation, and the filtrate is distilled under reduced pressure after the catalyst is filtered out; (3) Undecylenic acid is used as raw material, manganese dioxide and zeolite are used as catalysts, and formic acid is used for solid-phase catalytic reaction.
[Others]
It is easy to polymerize in air and unstable in acidic and alkaline media. |
|
