Question

draw a skeletal (\line\) structure of this molecule:
$\ce{ch3 - c(=o) - ch(ch(ch3)ch3) - ch2 - c(=o) - ch3}$

Explanation:

Step1: Identify Carbon Atoms and Functional Groups

First, we analyze the given molecular formula. The molecule has carbonyl groups (\(C=O\)) and various carbon - carbon bonds. Let's list the carbon atoms:

• The first carbonyl carbon: \(C\) in \(CH_3 - C(=O)-\)
• Then the carbon chain: \( - CH - CH_2 - C(=O)-CH_3\), and there is a branch at the second carbon (from the left carbonyl) with \(CH - CH_3\) and \(CH_3\) attached.

Step2: Draw the Skeletal Structure Basics

In skeletal (line) structure, we represent carbon atoms as vertices (or the ends of lines). We start by drawing the main carbon chain.

• The main chain has carbon atoms: from the first carbonyl (\(C = O\)) carbon, then a \(CH\) (with a branch), then a \(CH_2\), then a carbonyl \(C = O\), then a \(CH_3\).
• The branch at the second carbon (after the first carbonyl) has a \(CH\) (attached to \(CH_3\)) and another \(CH_3\) attached to that \(CH\).

Step3: Add Functional Groups and Branches

• Draw the two carbonyl groups (\(C = O\)) as double - bonded \(O\) to the appropriate carbon atoms.
• For the branch: at the carbon between the two carbonyl groups (the second carbon in the main chain, counting from the left carbonyl), we attach a branch with two \(CH_3\) groups (one directly on the \(CH\) and one on the adjacent \(CH\) in the branch).

The skeletal structure should look like this:

First, draw the main chain:

\(O=\) (attached to a carbon), then a line (representing \(CH\)) with a branch. The branch has a line (representing \(CH\)) with a \(CH_3\) at the end and another \(CH_3\) on the \(CH\) of the branch. Then a \(CH_2\) line, then \(O=\) (attached to a carbon), then a \(CH_3\).

In more precise terms, the skeletal structure is:

    CH3
    |
O   |   O
||  |   ||
C - C - C - C - C - CH3
    |   |
    CH3 CH2

Wait, let's re - elaborate. Let's number the carbons:

1. Carbon 1: \(C = O\) (attached to \(CH_3\))
2. Carbon 2: \(CH\) (with a branch)
3. Carbon 3: \(CH_2\)
4. Carbon 4: \(C = O\) (attached to \(CH_3\))

Branch on Carbon 2: Carbon 2 is bonded to a \(CH\) (Carbon 2a) which is bonded to \(CH_3\) (Carbon 2b) and another \(CH_3\) (on Carbon 2a).

So the skeletal structure:

    CH3
    |
O   |   O
||  |   ||
C - C - C - C - CH3
    |
    CH - CH3
    |
    CH3

Wait, no, let's correct the carbon numbering. Let's start from the left - most carbon:

• Left - most carbon: \(C\) in \(CH_3 - C(=O)-\) (Carbon 1)
• Carbon 2: \(CH\) (between Carbon 1 and Carbon 3)
• Carbon 3: \(CH_2\)
• Carbon 4: \(C(=O)\) (in \( - C(=O)-CH_3\))
• Carbon 5: \(CH_3\) (attached to Carbon 4)

Branch on Carbon 2: Carbon 2 is bonded to a \(CH\) (Carbon 6) which is bonded to \(CH_3\) (Carbon 7) and \(CH_3\) (Carbon 8) is bonded to Carbon 6.

So the skeletal structure:

    CH3 (Carbon 8)
    |
    C (Carbon 6) - CH3 (Carbon 7)
    |
O   |   O
||  |   ||
C (1) - C (2) - C (3) - C (4) - CH3 (5)

In a more standard skeletal drawing:

    CH3
    |
O   |   O
||  |   ||
C - C - C - C - CH3
    |
    C - CH3
    |
    CH3

Wait, actually, the correct skeletal structure is:

We can represent it as:

    CH3
    |
O   |   O
||  |   ||
C - C - C - C - CH3
    |
    CH - CH3
    |
    CH3

But to draw it properly, the key is to show the carbonyl groups, the main carbon chain, and the branch with two methyl groups.

Answer:

The skeletal (line) structure of the molecule is:

    CH₃
    |
O   |   O
║   |   ║
C - C - C - C - CH₃
    |
    CH - CH₃
    |
    CH₃

(Or in a more compact and standard drawing:

    CH3
    |
O   |   O
||  |   ||
C - C - C - C - CH3
    |
    C - CH3
    |
    CH3

where the double lines (\(||\)) represent the carbon - oxygen double bond, and the lines represent carbon - carbon bonds, with the \(CH_3\) groups as branches.)