Propose a mechanism to account for the formation of a cyclic acetal from 4-hydroxypentanal and one equivalent of methanol. If th
e carbonyl oxygen of 4-hydroxypentanal is enriched with oxygen-18, do you predict that the oxygen label appears in the cyclic acetal or in the water
1 answer:
Answer:
If carbonyl oxygen of 4-hydroxypentanal is enriched with , then the oxygen label appears in the water .
Explanation:
- In the first step, -OH group at C-4 gives intramolecular nucleophilic addition reaction at carbonyl center to produce a cyclic hemiacetal.
- Then, one equivalent of methanol gives nucleophilic substitiution reaction by substituting -OH group in cyclic hemiacetal to produce cyclic acetal.
- If carbonyl oxygen of 4-hydroxypentanal is enriched with
, then the oxygen label appears in the water produced at the end of reaction.
- Full reaction mechanism has been shown below.
You might be interested in
<h3>The density of H₂ = 0.033 g/L</h3><h3>Further explanation</h3>
In general, the gas equation can be written
where
P = pressure, atm , N/m²
V = volume, liter
n = number of moles
R = gas constant = 0.082 l.atm / mol K (P= atm, v= liter),or 8,314 J/mol K (P=Pa or N/m², v= m³)
T = temperature, Kelvin
n = N / No
n = mole
No = Avogadro number (6.02.10²³)
n = m / MW
m = mass
MW = molecular weight
For density , can be formulated :
P = 327 mmHg = 0,430263 atm
R = 0.082 L.atm / mol K
T = 48 ºC = 321.15 K
MW of H₂ = 2.015 g/mol
The density :