作业帮请教二道化学题（AP）
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请教二道化学题（AP）
(1)What is a reaction mechanism and how does it differ from a balanced chemical equation?
(2)Define the following general types of chemical reactions:
a.Addition;
b.Elimination;
b-1.Beta Elimination;
b-2.Alpha Elimination;
b-3.other than alpha- or beta-;
c.Displacement / Substitution;
d.Rearrangement;
e.Oxidation-Reduction.
(1)What is a reaction mechanism and how does it differ from a balanced chemical equation?
(2)Define the following general types of chemical reactions:
a.Addition;
b.Elimination;
b-1.Beta Elimination;
b-2.Alpha Elimination;
b-3.other than alpha- or beta-;
c.Displacement / Substitution;
d.Rearrangement;
e.Oxidation-Reduction.
(1)What is a reaction mechanism and how does it differ from a balanced chemical equation?
Ans :
A reaction mechanism provides a detailed step by step description of a reaction.
A balanced equation provides the number of moles of both reactants and products but does not show how the reaction proceeds.
2)Define the following general types of chemical reactions:
a.Addition:
Ans:
Two reactants combine to yield one product.Addition frequently occurs with organic compounds at double ortriple bonds and occasionally at small-sized rings.
b.Elimination:
Ans:
Elimination (Decomposition) is the reverse of addition because two or more atoms or groups are removed from one molecules.
b-1.Beta Elimination:
Ans:
Beta elimination involves removal from adjacent atoms and always leads to an increase in multiple bonding.
b-2.Alpha Elimination:
Ans:
Alpha elimination is the removal from same atom and produces a carbene if this atom is carbon.
b-3.other than alpha- or beta-;
Ans:
If elimination is other than from adjacent atoms or the same atom,a ring results.e.g.Removal from atom once removed (gamma-elimination) affords a three-membered ring.
Decomposition,a kind of elimination,is the energy-catalyzed
breakdown of a molecule into at least two molecule without the
intervention of any other reagent.
c.Displacement / Substitution:
Ans:
This is the replacement of one group by another.When an H is displaced,the reaction is called substitution.
d.Rearrangement:
Ans:
Bonds are scrambled to form an isomer.
e.Oxidation-Reduction.
Ans:
Redox involves transfer to electrons or change in oxidation number.Oxidation of a C is signaled by a decreased in the number of its bonded H's or an increase in its number of bonds to other atoms such as C,O,N,Cl,Br,F,and S.
All these names refer only to the net reaction as given by the cemical equation.For multistep mechanisms,individul steps may be of different types.
Ans :
A reaction mechanism provides a detailed step by step description of a reaction.
A balanced equation provides the number of moles of both reactants and products but does not show how the reaction proceeds.
2)Define the following general types of chemical reactions:
a.Addition:
Ans:
Two reactants combine to yield one product.Addition frequently occurs with organic compounds at double ortriple bonds and occasionally at small-sized rings.
b.Elimination:
Ans:
Elimination (Decomposition) is the reverse of addition because two or more atoms or groups are removed from one molecules.
b-1.Beta Elimination:
Ans:
Beta elimination involves removal from adjacent atoms and always leads to an increase in multiple bonding.
b-2.Alpha Elimination:
Ans:
Alpha elimination is the removal from same atom and produces a carbene if this atom is carbon.
b-3.other than alpha- or beta-;
Ans:
If elimination is other than from adjacent atoms or the same atom,a ring results.e.g.Removal from atom once removed (gamma-elimination) affords a three-membered ring.
Decomposition,a kind of elimination,is the energy-catalyzed
breakdown of a molecule into at least two molecule without the
intervention of any other reagent.
c.Displacement / Substitution:
Ans:
This is the replacement of one group by another.When an H is displaced,the reaction is called substitution.
d.Rearrangement:
Ans:
Bonds are scrambled to form an isomer.
e.Oxidation-Reduction.
Ans:
Redox involves transfer to electrons or change in oxidation number.Oxidation of a C is signaled by a decreased in the number of its bonded H's or an increase in its number of bonds to other atoms such as C,O,N,Cl,Br,F,and S.
All these names refer only to the net reaction as given by the cemical equation.For multistep mechanisms,individul steps may be of different types.