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As benzene is ubiquitous in gasoline and hydrocarbon fuels that are in use everywhere, human exposure to benzene is a global health problem. Benzene targets the liver, kidney, lung, heart and brain and can cause DNA strand breaks and chromosomal damage, hence is teratogenic and mutagenic. Benzene causes cancer in animals including humans.
One might summarize the timeline in the following way: the first 50 years were focused on the internal combustion engine and on refinery operations and, post 1970, emphasis has been placed on safety and automobile emissions. [19] 1900-1910 invention of spray carbeurator allowed use of "straight run gasoline" with vehicles.
This system of chemical notation—in which the elements were given simple written labels, such as O for oxygen, or Fe for iron, with proportions denoted by numbers—is the same basic system used today. The only difference is that instead of the subscript number used today (e.g., H 2 O), Berzelius used a superscript (H 2 O).
An image from John Dalton's A New System of Chemical Philosophy, the first modern explanation of atomic theory.. This timeline of chemistry lists important works, discoveries, ideas, inventions, and experiments that significantly changed humanity's understanding of the modern science known as chemistry, defined as the scientific study of the composition of matter and of its interactions.
The C 3-benzenes are a class of organic aromatic compounds which contain a benzene ring and three other carbon atoms. For the hydrocarbons with no further unsaturation, there are four isomers. The chemical formula for all the saturated isomers is C 9 H 12.
[6] [7] Due to the two step nature, the Raschig–Hooker process can be used to produce either chlorobenzene or phenol. Reaction scheme of the Raschig-Hooker process. The Raschig–Hooker process's ability to make phenol makes it comparable to other methods, such as the Dow and Bayer process, which also converts benzene into phenol. In fact ...
1928 - Kathleen Lonsdale used x-rays to determine that the structure of benzene is a flat hexagonal ring. [85] 1928 - Paul Niggli introduced reduced cells for simplifying structures using a technique now known as Niggli reduction. [86]
c. 520 BC – Alcmaeon of Croton distinguished veins from arteries and discovered the optic nerve. c. 450 BC – Sushruta wrote the Sushruta Samhita, redacted versions of which, by the third century AD, describe over 120 surgical instruments and 300 surgical procedures, classify human surgery into eight categories, and introduce cosmetic surgery.