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Anonymous users2024-02-07In two cases, one is that there is a hydroxyl group, and the alpha carbon, which is the adjacent carbon of the hydroxyl carbon, can be eliminated by hydrogen for a long time, and it can be dehydrated, and many alcohols can do this, in concentrated sulfuric acid.
180 degrees Celsius.
conditions. One is hydroxyl acid, which can form cycloesters and is also intramolecular dehydration, under the condition that concentrated sulfuric acid is heated, which is a reversible reaction, and generally saturated sodium carbonate is also required.
Purification. By the way, intramolecular dehydration refers to the dehydration of a molecule by itself, and there is also an intermolecular dehydration of the pure substance itself, which is the dehydration of two molecules in the pure substance, which is different in concept but sometimes easy to confuse.
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Anonymous users2024-02-06A few examples would be nice: 1Intramolecular dehydration: ethanol to ethylene ethanol is CH3CH2OH, a molecule of water is removed to obtain C2H4 (ethylene), this reaction needs to be heated to 170 degrees with concentrated H2SO4 2
Intermolecular dehydration: ethanol to ether is the same, and concentrated H2SO4 is heated to 140 degrees, ethanol will undergo intermolecular dehydration, that is, two ethanol molecules lose one molecule of water to form ether (CH3CH2OCH2CH3) 3Intermolecular dehydration:
Amino acid dehydration and condensation: The amino and carboxyl groups between different amino acids are dehydrogenated and hydroxyl groups are combined into water at the same time, and the amino acids are condensed into peptides (very important!). That's how proteins are formed).
Ethanol can undergo dehydration reactions catalyzed by concentrated sulfuric acid and high temperatures, and the products vary with different temperatures.
1) Eliminate (intramolecular dehydration) to make ethylene (170 concentrated sulfuric acid), and when producing, add broken porcelain pieces (or zeolite) to the flask to avoid boiling.
c2h5oh→ch2=ch2↑+h2o
2) Condensation (intermolecular dehydration) to ether (130 -140 concentrated sulfuric acid).
2C2H5OH C2H5OC2H5 + H2O (this is a substitution reaction).
dehydrogenation; When the vapor of ethanol passes through a dehydrogenation catalyst such as copper, silver, nickel or copper-chromium oxide at high temperatures, it is dehydrogenated to form aldehydes
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Anonymous users2024-02-05Question analysis: C2
H5OH has only one structure, intramolecular dehydration yields one product, and intermolecular dehydration yields one product, C3
H6OH has two structures, intramolecular dehydration yields one product, and intermolecular dehydration yields three products, C2
H5OH and C3
Two products can be obtained by intermolecular dehydration of H6OH, so 8 products can be obtained.
Comments: When giving the molecular formula, pay attention to whether there are isomers.
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Absorb water because blue alum is inorganic.
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