Question

How many structural isomers are there for a fivemember straight carbon chain with one double bond? For a six-member straight carbon chain with two double bonds?

Short answer

There are 4 structural isomers for a 5-member carbon chain with one double bond, and 6 structural isomers for a 6-member carbon chain with two double bonds.

Step-by-step solution

Find isomers for a 5-member carbon chain with 1 double bond

To find the number of structural isomers for the five-member carbon chain with one double bond, we can start by writing down the molecular formula for this compound. The molecular formula would be C5H10, given that there are 5 carbon atoms, and with a single double bond, the hydrogen count would be 2(n-1)+2 = 2(4)+2 = 10. Now, we need to find the possible positions for the double bond in the chain: 1. 1st and 2nd carbon atoms 2. 2nd and 3rd carbon atoms 3. 3rd and 4th carbon atoms 4. 4th and 5th carbon atoms These four possibilities represent the four possible structural isomers for a 5-member chain with one double bond.

Find isomers for a 6-member carbon chain with 2 double bonds

Next, we need to find the number of structural isomers for the six-member carbon chain containing two double bonds. The molecular formula of this compound would be C6H10, given that there are 6 carbon atoms, and two double bonds. Now, we need to find the possible positions for the double bonds in the chain: 1. 1st and 2nd carbon atoms, 3rd and 4th carbon atoms (non-conjugated) 2. 1st and 2nd carbon atoms, 4th and 5th carbon atoms (non-conjugated) 3. 1st and 2nd carbon atoms, 5th and 6th carbon atoms (non-conjugated) 4. 2nd and 3rd carbon atoms, 4th and 5th carbon atoms (conjugated) 5. 2nd and 3rd carbon atoms, 5th and 6th carbon atoms (non-conjugated) 6. 3rd and 4th carbon atoms, 5th and 6th carbon atoms (non-conjugated) These six possibilities represent the six possible structural isomers for a 6-member carbon chain with two double bonds. In conclusion, there are 4 structural isomers for a 5-member carbon chain with one double bond and 6 structural isomers for a 6-member carbon chain with two double bonds.

Key concepts

Organic Chemistry

Organic chemistry is a branch of chemistry that centers around the study of carbon-containing compounds. Carbon, due to its ability to form up to four covalent bonds, is the key element that allows the diversity in organic molecules. In this field, we explore myriad compounds and interactions, but the core focus is on understanding how carbon atoms bond with other elements, especially hydrogen, oxygen, and nitrogen.

One of the fundamental aspects is the study of hydrocarbons, which are compounds made solely of carbon and hydrogen. Understanding the structures, mechanisms, and reactions involving these molecules gives insight into various chemistries that power biological processes, industrial applications, and synthetic organic chemistry.

Overall, organic chemistry is all about how carbon forms the backbone of compounds. It establishes the basis for an array of molecules, enabling a plethora of chemical features and reactions to arise from relatively simple building blocks.

Carbon Chains

Carbon chains refer to sequences of carbon atoms that are linked together. These chains form the foundation of organic molecules. Depending on how the atoms are arranged, these chains can vary tremendously in shape and size.

Carbon can bond in various ways to form chains that are:

• Straight (linear)
• Branched
• Cyclic (rings)

Length and branching can significantly influence the properties of the compounds. Linear chains usually have different chemical behaviors than branched ones. For example, the boiling and melting points might differ based on the structure and chain length.

When considering just carbon and hydrogen, these chains are the simplest example of hydrocarbons. The basic alkane series represents carbon chains with only single bonds, while more complex chains include double or even triple bonds, adding new layers of understanding to how these structures behave and interact.

Double Bonds

Double bonds are a type of covalent bond where two pairs of electrons are shared between two atoms. In the context of organic chemistry, this often occurs between carbon atoms. Double bonds play a pivotal role in determining the nature and reactivity of organic molecules.

They not only affect the physical properties like boiling and melting points but also impact the chemical reactivity of compounds. Double bonds are more reactive than single bonds due to the higher electron density. They can participate in reactions such as addition, where atoms or groups of atoms are added to the carbon atoms forming the bond.

Another notable feature is that double bonds restrict the rotation around the bond axis, giving rise to different isomeric forms when other groups are attached to the carbons involved in the double bond. This rigidity is a critical factor in the study of geometrical isomerism, where the spatial arrangement of atoms affects the overall properties of the compounds.

Isomerism

Isomerism is a concept that underscores the structural diversity of organic compounds. Isomers are molecules that have the same molecular formula but different structural arrangements, leading to different properties. The most relevant to our topic is structural isomerism, where the connectivity of atoms differs.

In structural isomerism:

• The order in which atoms are bonded can change.
• Isomers may have different branching in carbon chains.
• They may include differences in the location of functional groups or double bonds.

These variations cause significant layout changes, which influence the compound's physical and chemical properties. For example, position isomers change the position of the double bond within the carbon chain, affecting properties such as reactivity and boiling points.

Analyzing structural isomers is crucial when determining possible variants of a molecule with a given formula, as seen in exercises involving carbon chains with double bonds, where various positions lead to unique isomeric compounds.