Draw the products of Claisen condensation of (a) ethyl propanoate; (b) ethyl-3-methylbutanoate; (c) ethyl pentanoate. For each,
the base used is sodium ethoxide and the solvent is ethanol.
1 answer:
Answer:
Structures of products has been shown below
Explanation:
- In claisen condensation, two ester molecules combines with each other through nucleophilic acyl substitution resulting formation of a
-ketoester.
- At first, one ester molecule gets deprotonated in presence of a strong base e.g. NaOEt yielding a carbanion.
- The carbanion then gives nucleophilic acyl substitution reaction with another ester molecule to replace alkoxy group present in ester group
- General reaction mechanism of claisen condensation along with products of given esters are shown below.
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Answer:
E₁ ≅ 28.96 kJ/mol
Explanation:
Given that:
The activation energy of a certain uncatalyzed biochemical reaction is 50.0 kJ/mol,
Let the activation energy for a catalyzed biochemical reaction = E₁
E₁ = ??? (unknown)
Let the activation energy for an uncatalyzed biochemical reaction = E₂
E₂ = 50.0 kJ/mol
= 50,000 J/mol
Temperature (T) = 37°C
= (37+273.15)K
= 310.15K
Rate constant (R) = 8.314 J/mol/k
Also, let the constant rate for the catalyzed biochemical reaction = K₁
let the constant rate for the uncatalyzed biochemical reaction = K₂
If the rate constant for the reaction increases by a factor of 3.50 × 10³ as compared with the uncatalyzed reaction, That implies that:
K₁ = 3.50 × 10³
K₂ = 1
Now, to calculate the activation energy for the catalyzed reaction going by the following above parameter;
we can use the formula for Arrhenius equation;
If &
E₁ ≅ 28.96 kJ/mol
∴ the activation energy for a catalyzed biochemical reaction (E₁) = 28.96 kJ/mol
Answer:
29Si has a natural abundance of 4.68%.
30Si has a relative atomic mass of 29.99288 and a natural abundance of 3.09%.
Explanation:
The atomic mass of silicon is given by:
Si=Si²⁸×A₁+Si²⁹×A₂+Si³⁰×A₃
Where:
Si: atomic mass of silicon (28.086)
Si²⁸: relative atomic mass of 28Si (27.97693)
A₁: natural abundance of 28Si (92.23%)
Si²⁹: relative atomic mass of 29Si (28.97649)
A₂: natural abundance of 29Si
Si³⁰: relative atomic mass of 30Si
A₃: natural abundance of 30Si
We also know that 30Si natural abundance is in the ratio of 0.6592 to that of 29Si.
We have to set up a system of three equations in three unknowns:
Si=Si²⁸×A₁+Si²⁹×A₂+Si³⁰×A₃
A₃=0.6592×A₂
A₁+A₂+A₃=1
First, we find substitute the value of A₃ in the third equation and solv teh value of A₂:
A₁+A₂+0.6592×A₂=1
A₁+1.6592×A₂=1
1.6592×A₂=1-A₁
A₂==0.0468
Then, we find the value of A₃:
A₃=0.6592×A₂
A₃=0.6592×0.0468=0.0309
Finally, we find the value of Si³⁰ in the first equation:
Si=Si²⁸×A₁+Si²⁹×A₂+Si³⁰×A₃
28.086=27.97693×0.9223+28.97649×0.0468+Si³⁰×0.0309
28.086=27.15922+Si³⁰×0.0309
28.086-27.15922=Si³⁰×0.0309
=Si³⁰
Si³⁰=29.99288