Question

Write the condensed structural formula for each of the following compounds: (a) 2 -pentanol, (b) 1,2-propanediol, (c) ethyl acetate, (d) diphenyl ketone, (e) methyl ethyl ether.

Short answer

The condensed structural formulas for the given compounds are: (a) 2-pentanol: CH3CH2CH(OH)CH2CH3 (b) 1,2-propanediol: CH2(OH)CH2(OH)CH3 (c) ethyl acetate: CH3COOCH2CH3 (d) diphenyl ketone: (C6H5)2CO (e) methyl ethyl ether: CH3OCH2CH3

Step-by-step solution

(a) 2-pentanol

First, let's analyze the name "2-pentanol": - "Pent" indicates that the compound has 5 carbon atoms. - "an" indicates that it's an alkane, meaning it has single bonds between the carbon atoms. - "ol" indicates the presence of an alcohol group (-OH) attached to the carbon atom. - "2" indicates the position (numbering starts from 1) of the carbon atom to which the -OH group is attached. Putting all the pieces together, the condensed structural formula for 2-pentanol is CH3CH2CH(OH)CH2CH3.

(b) 1,2-propanediol

Analyze the name "1,2-propanediol": - "Prop" represents 3 carbon atoms. - "an" indicates that it's an alkane. - "diol" indicates the presence of two alcohol groups (-OH). - "1,2" indicates the position of the carbon atoms to which the -OH groups are attached. The condensed structural formula for 1,2-propanediol is CH2(OH)CH2(OH)CH3.

(c) ethyl acetate

Analyze the name "ethyl acetate": - "Ethyl" represents an ethyl group (CH3CH2-). - "acetate" is the ester (R-COO-R') deriving from acetic acid (CH3COOH). The condensed structural formula for ethyl acetate is CH3COOCH2CH3.

(d) diphenyl ketone

Analyze the name "diphenyl ketone": - "Di" indicates the presence of two phenyl groups (C6H5-). - "ketone" represents a carbonyl group (C=O) attached to an alkyl or aryl group. The condensed structural formula for diphenyl ketone is (C6H5)2CO.

(e) methyl ethyl ether

Analyze the name "methyl ethyl ether": - "Methyl" represents a methyl group (CH3-). - "ethyl" represents an ethyl group (CH3CH2-). - "ether" indicates the presence of an oxygen atom between the two alkyl groups. The condensed structural formula for methyl ethyl ether is CH3OCH2CH3.

Key concepts

Organic Chemistry

Organic chemistry is the fascinating branch of science that focuses on compounds primarily composed of carbon. These compounds form the foundation of various life forms on Earth. In organic chemistry, hydrocarbons serve as the backbone, mingling with other elements such as hydrogen, oxygen, nitrogen, and more to create diverse molecules.

Organic compounds can include functional groups which define their chemical characteristics and reactions. These functional groups are important because they dictate how the molecules behave and react under different conditions. Some common functional groups include alcohols, ethers, and esters, which we'll explore further.

• Hydrocarbons – Molecules consisting of only carbon and hydrogen.
• Functional groups – Specific groups of atoms within molecules that have their characteristic properties.
• Carbon's ability to form stable bonds allows for a vast array of organic compounds.

Understanding the structure and reactivity of these compounds is crucial in many aspects of chemical, biological, and environmental sciences.

Alcohols

Alcohols are organic compounds characterized by a hydroxyl group (-OH) bonded to a carbon atom. They are named by replacing the "-e" ending of the parent hydrocarbon with "-ol," reflecting their identity as alcohols. The position of the -OH group is significant and is usually indicated by numbering the carbon chain.

Saegol, from "2-pentanol" to "1,2-propanediol", alcohols can vary in complexity. Let's look at examples:

• 2-pentanol: A five-carbon chain (pent-) with an -OH on the second carbon. Formula: CH3CH2CH(OH)CH2CH3.
• 1,2-propanediol: A three-carbon chain (prop-) with -OH groups on the first and second carbons. Formula: CH2(OH)CH2(OH)CH3.

The presence of an alcohol group gives these compounds certain physical characteristics, such as higher boiling points compared to similar hydrocarbons due to hydrogen bonding.

Ethers

Ethers are a class of organic compounds that feature an oxygen atom singly bonded to two alkyl or aryl groups. This unique structure results in ethers often being more polar than hydrocarbons but less so than alcohols. Unlike alcohols, ethers do not contain an -OH group.

The naming of ethers generally involves citing the names of the attached groups in alphabetical order followed by "ether." For example, in methyl ethyl ether:

• "Methyl" (from CH3-) and "ethyl" (from CH3CH2-) represent the two alkyl groups.
• This compound has the structural formula CH3OCH2CH3.

Ethers are notable for their relatively low reactivity compared to other organic compounds, which makes them excellent solvents in laboratory settings.

Esters

Esters are organic compounds derived from the reaction between an alcohol and an acid. This reaction removes water (a process called esterification) and results in a molecule featuring a characteristic -COO- linkage.

Ethyl acetate, for instance, is formed by combining ethyl alcohol (ethanol) and acetic acid. Its condensed structural formula is CH3COOCH2CH3, where the acid fragment (CH3CO-) comes from acetic acid, and the alcohol part (CH2CH3) derives from ethanol.

Esters are known for their pleasant, often fruity odors, making them valuable in the fragrance industry. They also play significant roles in biochemistry and some industrial applications.

• Appearance: Typically colorless liquids or solids with characteristic pleasant odors.
• Applications: Used in making artificial flavors or fragrances, solvents, and plastics.

Ketones

Ketones are a distinct category of organic compounds, characterized by the presence of a carbonyl group (C=O) bonded to two carbon atoms. This structure can be seen in molecules with varying degrees of complexity. A typical naming convention for ketones involves identifying the parent hydrocarbon and changing the suffix to "-one."

Diphenyl ketone (commonly known as benzophenone) is an example where the carbonyl group is flanked by two phenyl rings (C6H5-). Its formula can be written as (C6H5)2CO. This ketone is particularly significant in the perfume industry due to its use in making some fragrances.

The simplicity and reactivity of ketones make them vital in various chemical reactions and processes:

• Reactivity: The carbonyl group is highly reactive, making ketones crucial in organic synthesis.
• Applications: Frequently used as solvents, in perfumery, and in the production of pharmaceuticals.

Understanding ketones' structure and function can significantly broaden one's grasp of organic chemistry's roles in everyday materials and industry.