How long will it take for 100 grams of a substance with a half-life of 2 years to decay to a mass of 50 grams?
1 answer:
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Answer:
Four possible isomers (1–4) for the natural product essramycin. The structure of compound 1 was attributed to essramycin by 1H NMR, 13C NMR, HMBC, HRMS, and IR experiments.
Explanation:
Three synthetic routes were used to prepare all four compounds (Figure 2A). All three reactions utilize 2-(5-amino-4H-1,2,4-triazol-3-yl)-1-phenylethanone (5) as the precursor, whereas each uses different esters (6–8) to construct the pyrimidinone ring. Isomer 1 was prepared by reaction A, which used triazole 5 and ethyl acetoacetate (6) in acetic acid. This was the reaction used in syntheses of essramycin by the Cooper and Moody laboratories.3,4 Reaction B produced compound 2 (minor product) and compound 3 (major product), which were separated chromatographically. This reaction allowed reagent 5 to react with ethyl 3-ethoxy-2-butenoate (7) in the presence of sodium in methanol, under reflux for 24 h. Compound 4 was prepared by reaction C, which was obtained by reflux of 5 and methyl 2-butynoate (8) in n-butanol.
Answer : The value of is, 0.5 and
= positive.
Explanation :
The unimolecular reaction is:
In unimolecular reaction, the starting material is 2 times to the product.
.........(1)
As we know that:
...........(2)
Now substitute equation 1 in 2, we get:
Now we have to calculate the value of at 298 K.
where,
= standard Gibbs free energy = ?
R = gas constant = 8.314 J/mol.K
T = temperature = 298 K
= equilibrium constant = 0.5
Now put all the given values on the above formula, we get:
Thus, the value of at 298 K is, 1717.32 J/mol
As we know that:
= +ve, reaction is non spontaneous
= -ve, reaction is spontaneous
= 0, reaction is in equilibrium
Thus, the = +ve. So, the reaction is non spontaneous.