Question

Draw a condensed structure to correspond to each of the following names. (a) methylbutane; (b) cyclohexene; (c) 2 -methyl- 3 -hexyne; (d) 2 -butanol; (e) ethyl isopropyl ether; (f) propanal

Short answer

The condensed structures are (a) Methylbutane: \(\CH_3CH(CH_3)CH_2CH_3\), (b) Cyclohexene: \( \CH_2CH=CHCH_2CH_2CH_2\), (c) 2 -methyl- 3 -hexyne: \( \CH_3CH(C≡C)CH_2CH_2CH_3\), (d) 2 -butanol: \( \CH_3CH(OH)CH_2CH_3\), (e) Ethyl isopropyl ether: \( \CH_3CH_2OCH(CH_3)_2\), (f) Propanal: \( \CH_3CH_2CHO\).

Step-by-step solution

Drawing Methylbutane

Methylbutane consists of a butane chain, which is a four-carbon alkane, and a methyl group located anywhere along the chain except the ends (as this would result in a longer alkane). Thus, the condensed structure is \(\ CH_3CH(CH_3)CH_2CH_3 \).

Drawing Cyclohexene

Cyclohexene consists of a hexene ring, which is a six-carbon ring with a double bond. No other groups or parameters are mentioned, so the condensed structure is \(\CH_2CH=CHCH_2CH_2CH_2 \).

Drawing 2 -methyl- 3 -hexyne

This compound has a six-carbon chain (hex-) with a triple bond (-yne) at the third carbon and a methyl group (-methyl) at the second carbon. Thus, the condensed structure is \(\CH_3CH(C≡C)CH_2CH_2CH_3 \).

Drawing 2 -butanol

This compound consists of a butane chain, which is a four-carbon alkane, with an alcohol group (-ol) at the second carbon. Thus, the condensed structure is \(\CH_3CH(OH)CH_2CH_3 \).

Drawing Ethyl isopropyl ether

This compound has an ether function group (an oxygen linked to two alkyl groups) between an ethyl and isopropyl groups. Thus, the condensed structure is \(\CH_3CH_2OCH(CH_3)_2 \).

Drawing Propanal

This compound consists of a propane chain, which is a three-carbon alkane, with an aldehyde group (-al) at the end of the chain. Thus, the condensed structure is \(\CH_3CH_2CHO \).

Key concepts

Organic Chemistry

Organic chemistry is the branch of chemistry that deals with the structure, properties, and reactions of compounds that contain carbon. These compounds are vital to life on Earth. Organic chemistry is fundamental for creating the substances that form the basis of various industries, including pharmaceuticals, petrochemicals, and agriculture.

One reason organic chemistry is such an expansive field is the ability of carbon to form stable bonds with other carbon atoms and a variety of different elements. This creates endless possibilities for forming compounds with both simple and complex structures. Understanding how these compounds form and interact is key to learning how materials behave and are transformed through chemical reactions.

In organic chemistry, condensed molecular structures are a shorthand notation that helps chemists represent molecules in a more compact format. This type of notation is particularly useful when discussing or drawing organic molecules since it focuses on connectivity rather than the layout of atoms.

Functional Groups

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. A functional group can include parts of molecules like double bonds, alcohol groups, or more complex arrangements of anti-chemical groups, such as esters or ethers.

Functional groups define the chemical reactivity and properties of organic compounds. For instance, in the exercise provided, the alcohol group (-OH) in 2-butanol signifies that this compound is likely to engage in reactions typical of alcohols, such as dehydration or oxidation. Ethyl isopropyl ether contains an ether group, characterized by an oxygen atom connected to two alkyl or aryl groups, depicting ethers' functionality.

Recognizing functional groups helps predict how a compound will react in different conditions, pinpoints its affinity for energy exchange, and allows chemists to synthesize new compounds with desired properties.

Alkanes

Alkanes are the simplest type of organic compounds composed entirely of carbon and hydrogen atoms arranged in a tree structure, with single bonds only. They are also known as paraffins and are saturated hydrocarbons because each carbon atom forms four single covalent bonds.

Alkanes follow the general formula \H_{2n+2} where \(n\) is the number of carbon atoms. For example, in the exercise above, "methylbutane" is a derivate of "butane" - a four-carbon alkane. The methyl group in methane (\(CH_4\)) can be seen as the simplest alkane, while longer chains like propane (\(C_3H_8\)) and butane (\(C_4H_10\)) build on this format. They are typically nonreactive under normal conditions but can undergo reactions like combustion, halogenation, and cracking.

Alkanes are important in chemistry and everyday life. They serve as fuels and lubricants and are used to synthesize other compounds.

Chemical Nomenclature

Chemical nomenclature is the system of naming chemical compounds based on their structure and composition. It's a universal language that chemists have developed for clarity and consistency in communication. IUPAC (International Union of Pure and Applied Chemistry) nomenclature is the most widely used system for naming organic compounds.

Guidelines for nomenclature take into account the type of compound and its structure. For instance, the names like "methylbutane" or "propanal" provide specific information about the molecule’s structure. "Propanal" indicates an aldehyde with a three-carbon alkyl chain, while "cyclohexene" implies a cyclic structure with a double bond.

Each name follows a set of rules to avoid ambiguity. Understanding the rules of chemical nomenclature helps in identifying the type of compound and predicting its properties by interpreting its name. For students, mastering these naming conventions is an invaluable skill and often the first step toward deeper chemistry insight.