1,3-pentadiene reacts with HBr. When the double bond at the 3-position reacts, the hydrogen attaches to the 4-carbon, thus forming an allylic carbocation with delocalized electrons. This carbocation has another resonance structure. Because there are equal amounts of diene and hydrogen bromide, in which molecule only one of the double bonds reacts. Which of the following correctly describes this new resonance structure? a) It has a double bond between carbons 3 and 4 b) It has a positive charge on carbon 2 c) It has a positive charge on carbon 4 d) It has a double bond between carbons 2 and 3
Reactions of Ethers
Ethers (R-O-R’) are compounds formed by replacing hydrogen atoms of an alcohol (R-OH compound) or a phenol (C6H5OH) by an aryl/ acyl group (functional group after removing single hydrogen from an aromatic ring). In this section, reaction, preparation and behavior of ethers are discussed in the context of organic chemistry.
Epoxides
Epoxides are a special class of cyclic ethers which are an important functional group in organic chemistry and generate reactive centers due to their unusual high reactivity. Due to their high reactivity, epoxides are considered to be toxic and mutagenic.
Williamson Ether Synthesis
An organic reaction in which an organohalide and a deprotonated alcohol forms ether is known as Williamson ether synthesis. Alexander Williamson developed the Williamson ether synthesis in 1850. The formation of ether in this synthesis is an SN2 reaction.
1,3-pentadiene reacts with HBr. When the double bond at the 3-position reacts, the hydrogen attaches to the 4-carbon, thus forming an allylic carbocation with delocalized electrons. This carbocation has another resonance structure. Because there are equal amounts of diene and hydrogen bromide, in which molecule only one of the double bonds reacts.
Which of the following correctly describes this new resonance structure?
a) It has a double bond between carbons 3 and 4
b) It has a positive charge on carbon 2
c) It has a positive charge on carbon 4
d) It has a double bond between carbons 2 and 3
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