# Question #45498

Mar 14, 2017

Here's what I get.

#### Explanation:

3-Ethyl-2-methylnonane

(a) Structural formula

The parent alkane is nonane.

Draw chain of 9 carbon atoms.

Number the carbons from 1 to 9 (the direction doesn't matter, although I numbered from left to right).

Put an ethyl group on carbon-3 and a methyl group on carbon-2.

(b) Condensed structural formula

You write the substituent groups in parentheses immediately after the carbon atom to which they are attached.

${\text{CH"_3"CH"("CH"_3)"CH"("CH"_2"CH"_3)"CH"_2"CH"_2"CH"_2"CH"_2"CH"_2"CH}}_{3}$

4-Methylhept-2-ene

(a) Structural formula

The hept tells you that the parent hydrocarbon contains seven carbon atoms.

Draw a 7-carbon chain.

Number the carbon atoms from 1 to 7.

The 2-ene tells you that there is a $\text{C=C}$ double bond between carbons 2 and 3.

Now, attach a methyl group to carbon 4.

(b) Condensed structural formula

You can omit single bonds, but you can't omit double bonds.

The condensed structural formula is

${\text{CH"_3"CH"_2"CH"_2"CH"("CH"_3)"CH=CHCH}}_{3}$

5,6-Dimethyl-2-octane

There is no compound with this name.

1,3-Diethylhexane

This is an incorrect name.

Add ethyl groups at carbons 1 and 3.

We see that the longest continuous chain consists of 8 carbon atoms.

The correct name is 4-ethyloctane.

(b) Condensed structural formula

${\text{CH"_3"CH"_2"CH"_2"CH"_2"CH"("CH"_2"CH"_3)"CH"_2"CH"_2"CH}}_{3}$