Question

Draw the structural formula, showing all \(\mathrm{C}\) and \(\mathrm{H}\) atoms, for 6 -methyl-4-propyl-2octene.

Short answer

The final structure of 6-methyl-4-propyl-2-octene is: ``` CH_3 CH_3-CH_2-CH_3 | | CH_3-CH_2-C=CH-CH_2-CH(CH_3)-CH_2-CH_3 ``` In this structure, the main chain has 8 carbon atoms, with a double bond between the second and third carbons. The methyl group is attached to the sixth carbon and the propyl group is attached to the fourth carbon.

Step-by-step solution

Identify the main chain

The main chain has the prefix "oct-" which indicates that it is composed of 8 carbons.

Identify the double bond position

The "ene" suffix indicates the presence of a double bond. The number "2" in 2-octene indicates that the double bond is between the second and third carbon atoms in the main chain.

Identify the positions of the substituent groups

The substituent groups are 6-methyl and 4-propyl. The "6-methyl" means there is a methyl group (CH_3) attached to the sixth carbon atom on the main chain. Similarly, the "4-propyl" means there is a propyl group (C_3H_7) attached to the fourth carbon atom on the main chain.

Draw the main chain with the double bond

Draw a straight chain of 8 carbon atoms and number them from 1 to 8. Put a double bond between the second and third carbon atoms.

Add the substituent groups

Attach a methyl group (CH_3) to the sixth carbon atom and a propyl group (C_3H_7) to the fourth carbon atom.

Add the hydrogen atoms

Attach hydrogen atoms to each carbon atom, such that each carbon forms 4 bonds in total. Remember that carbon atoms with a double bond should have one less hydrogen atom. The final structure of 6-methyl-4-propyl-2-octene is: ``` CH_3 CH_3-CH_2-CH_3 | | CH_3-CH_2-C=CH-CH_2-CH(CH_3)-CH_2-CH_3 ``` In this structure, the main chain has 8 carbon atoms, with a double bond between the second and third carbons. The methyl group is attached to the sixth carbon and the propyl group is attached to the fourth carbon.

Key concepts

Structural Formula

In organic chemistry, understanding how to represent and interpret structural formulas is essential, as they provide a clear visualization of the molecular structure of a compound. A structural formula displays not only the number of atoms but also their arrangement in space, showing how they are bonded to each other. Take, for example, the molecule 6-methyl-4-propyl-2-octene. To accurately represent this molecule, you must first identify the main chain, which is an octane structure indicating eight carbon atoms are bonded in a long chain.

Next, we decode the molecular name to map the specific structure. The term '2-octene' points to a double bond located between the second and third carbon atoms. The prefix '6-methyl' and '4-propyl' denote branches (also known as substituent groups) attached to the main chain at the sixth and fourth carbons, respectively. The structural formula becomes a practical roadmap, showing how the chains and branches are linked together to create the complete molecule. Without such structural clarity, understanding the properties and behavior of organic molecules would be much harder.

Alkenes

Alkenes play a pivotal role in organic chemistry and are characterized by the presence of at least one carbon-carbon double bond, represented by \(C=C\). This bond is key to the molecule's reactivity and properties. In naming alkenes, the suffix '-ene' indicates the presence of this double bond. In the context of our molecule, 6-methyl-4-propyl-2-octene, the '2-octene' segment informs us that we are dealing with an eight-carbon alkene and the double bond is specifically between the second and third carbon atoms.

Alkenes are known for their ability to undergo addition reactions, where atoms or groups are added to the carbon atoms of the double bond, breaking the \(C=C\) and creating new single bonds. This reaction tendency makes alkenes very useful in creating a wide variety of compounds in organic synthesis.

Substituent Groups

In organic molecules, substituent groups are atoms or groups of atoms attached to the main carbon chain, and they play a significant role in defining the molecule's overall structure and properties. There are a variety of substituents, from simple ones like methyl (\(CH_3\)) and ethyl (\(C_2H_5\)) to more complex ones like propyl (\(C_3H_7\)) in 6-methyl-4-propyl-2-octene.

The position of these groups is indicated by numbers corresponding to the carbon atom they are attached to within the main chain. In this case, 6-methyl-4-propyl tells us that a methyl group is bonded to the sixth carbon and a propyl group is attached to the fourth carbon. These substituent groups can drastically influence the molecule's physical and chemical behavior, such as its boiling point, solubility, and reactivity patterns, making accurate placement on the main chain crucial for predicting its characteristics and reactions.