Question

Draw all the possible noncyclic structural isomers of \(\mathrm{C}_{5} \mathrm{H}_{10}\) Name each compound.

Short answer

The six possible noncyclic structural isomers of C5H10 are: 1. Pent-1-ene: C=C-C-C-C 2. Pent-2-ene: C-C=C-C-C 3. 3-methylbut-1-ene: C=C-C(C)-C 4. 2-methylbut-2-ene: C-C=C(C)-C 5. 2-methylbut-1-ene: C-C(C=C)-C 6. 3-methylbut-1-ene: C-C(C)-C=C

Step-by-step solution

Calculate the degree of unsaturation

To find the index of hydrogen deficiency/degree of unsaturation, we use the formula: IHD = (2 * Number_of_carbon + 2 - Number_of_hydrogen) / 2 For C5H10: IHD = (2 * 5 + 2 - 10) / 2 IHD = (10 + 2 - 10) / 2 IHD = 1 We have a degree of unsaturation of 1, which means there is one double bond or ring in each of our isomers. Since we are specifically looking for noncyclic structural isomers, each of our isomers will have one double bond.

Identify the initial structures

We'll start by identifying the initial structures of the isomers without including the double bond yet. We'll have a linear structure (5 carbons in a line) and several branched structures (branches starting from the 2nd or 3rd carbon in the chain). They are as follows: 1. Linear: C-C-C-C-C 2. Branched: (C-C(C)-C-C) 3. Branched: (C-C-C(C)-C)

Add the double bonds and draw the isomers

Now, we'll add the double bond to each structure, making sure we only have one double bond per isomer. 1. For the linear structure (C-C-C-C-C): Add the double bond at different positions: i. C=C-C-C-C ii. C-C=C-C-C 2. For the branched structure (C-C(C)-C-C): Add the double bond at different positions: i. C=C-C(C)-C ii. C-C=C(C)-C iii. C-C(C=C)-C iv. C-C(C)-C=C 3. For the branched structure (C-C-C(C)-C): Add the double bond at different positions: i. C=C-C(C)-C ii. C-C=C(C)-C In total, we have six different isomers of C5H10.

Name each compound

Now let's name each of the isomers using IUPAC rules: 1. C=C-C-C-C: Pent-1-ene 2. C-C=C-C-C: Pent-2-ene 3. C=C-C(C)-C: 3-methylbut-1-ene 4. C-C=C(C)-C: 2-methylbut-2-ene 5. C-C(C=C)-C: 2-methylbut-1-ene 6. C-C(C)-C=C: 3-methylbut-1-ene Thus, the six possible noncyclic structural isomers of C5H10 are: pent-1-ene, pent-2-ene, 3-methylbut-1-ene, 2-methylbut-2-ene, 2-methylbut-1-ene, and 3-methylbut-1-ene.