Naming Alcohols - IUPAC Nomenclature

The Organic Chemistry Tutor
21 Apr 201810:42
EducationalLearning
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TLDRThis chemistry lesson focuses on the nomenclature of alcohols, starting with common names like methanol and ethanol, and moving on to IUPAC naming conventions. It explains the process of naming alcohols with various substituents, including multiple hydroxyl groups and functional groups like halides. The lesson also covers the naming of alcohols on rings, emphasizing the importance of providing clear and specific information to uniquely identify each molecule.

Takeaways
  • 🧪 The common name for CH3OH is methyl alcohol or methanol, highlighting the importance of recognizing basic alcohol structures.
  • 🍶 Ethyl alcohol, also known as ethanol, is another fundamental alcohol with the chemical formula CH3CH2OH.
  • 🔍 Isopropyl alcohol is differentiated from other alcohols by its isopropyl group attached to the OH group.
  • 🌟 Tert-butyl alcohol is a unique alcohol with a tertiary butyl group, emphasizing the variety in alcohol structures.
  • 📝 The IUPAC nomenclature for alcohols is based on the position of the OH group and the length of the carbon chain, as seen in 2-propanol.
  • 🔢 In the case of multiple substituents, the alcohol group takes priority in naming, followed by the substituents in alphabetical order.
  • 🔄 When naming alcohols with multiple hydroxyl groups, the molecule is referred to as a 'diol', such as 3,4-hexanediol.
  • 🌐 For cyclic alcohols, the position of the OH group is crucial, and the naming reflects the substituents' positions, like in 3-ethyl cyclohexanol.
  • 📐 The direction of counting in the IUPAC nomenclature can affect the substituents' numbering, aiming for the lowest possible numbers.
  • 🌿 Condensed structures need to be expanded into line structures for proper IUPAC naming, as demonstrated with the methoxy and hydroxy groups.
  • 📚 Understanding the IUPAC nomenclature rules for alcohols is essential for accurately naming and identifying different alcohol molecules.
Q & A

  • What is the common name for the molecule CH3OH?

    -The common name for CH3OH is methyl alcohol, and it is also known as methanol.

  • What is the common name for the alcohol with the molecular formula CH3CH2OH?

    -The common name for the alcohol CH3CH2OH is ethyl alcohol, also known as ethanol.

  • What is the IUPAC name for the alcohol with an isopropyl group attached to the OH group?

    -The IUPAC name for the alcohol with an isopropyl group attached to the OH group is 2-propanol.

  • How is the alcohol with a tertiary butyl group attached to the OH group named according to IUPAC nomenclature?

    -The alcohol with a tertiary butyl group attached to the OH group is named 2-methyl-2-propanol according to IUPAC nomenclature.

  • What is the difference between naming an alcohol and an alkyl halide in IUPAC nomenclature?

    -In IUPAC nomenclature, the alcohol is given priority over the alkyl halide when naming a molecule, as the alcohol determines the parent chain and the position of the hydroxyl group.

  • How do you name a molecule with two hydroxyl groups?

    -A molecule with two hydroxyl groups is named as a diol, and the positions of the hydroxyl groups are indicated in the name, such as 3,4-hexanediol.

  • What is the IUPAC name for the molecule with a hydroxyl group on carbon 1 and a bromine atom on carbon 4 of a five-carbon chain?

    -The IUPAC name for this molecule is 4-bromo-1-pentanol.

  • When numbering a molecule with multiple substituents, what should be done to ensure the correct IUPAC name?

    -When numbering a molecule with multiple substituents, the direction that gives the lowest possible numbers for the substituents should be chosen, and the substituents should be listed in alphabetical order in the name.

  • How do you name an alcohol with a methoxy group and a hydroxyl group on a four-carbon chain?

    -The alcohol with a methoxy group on carbon 4 and a hydroxyl group on carbon 1 of a four-carbon chain is named 4-methoxy-1-butanol.

  • What is the naming convention for an alcohol with a hydroxyl group on a cycloalkane ring?

    -An alcohol with a hydroxyl group on a cycloalkane ring is named by adding the prefix 'cyclo' followed by the number of carbons in the ring and the suffix '-anol', such as cyclopentanol.

  • How do you name a molecule with two substituents on a cycloalkane ring, such as an ethyl group and a hydroxyl group?

    -A molecule with two substituents on a cycloalkane ring is named by numbering the ring to give the lowest possible numbers to the substituents and then listing them in alphabetical order, such as 3-ethylcyclohexanol.

Outlines
00:00
🧪 Basic Alcohol Nomenclature

This paragraph introduces the basics of naming alcohols with common examples. Methyl alcohol (CH3OH) and ethyl alcohol (CH3CH2OH) are highlighted, along with their common names, methanol and ethanol, respectively. The paragraph also covers the IUPAC nomenclature for isopropyl alcohol (2-propanol) and tert-butyl alcohol, explaining how to number the carbon chain and assign the correct suffixes.

05:06
🔍 Advanced Alcohol Nomenclature and Ring Systems

This paragraph delves into more complex alcohol nomenclature, including alcohols with multiple substituents and those on ring structures. It explains the process of naming alcohols with two hydroxyl groups as diols, such as 3,4-hexanediol, and how to prioritize functional groups over other substituents, exemplified by 4-bromo-1-pentanol. The paragraph also addresses the nomenclature of alcohols with multiple substituents, emphasizing the importance of alphabetical order and numbering for clarity. Additionally, it covers how to name alcohols in condensed structures and ring systems, including cycloalkanol and examples with multiple substituents on a ring, such as 2-ethyl-5-methylcyclohexanol.

Mindmap
Keywords
💡Alcohols
Alcohols are a class of organic compounds characterized by the presence of one or more hydroxyl (-OH) groups attached to a carbon atom. In the context of the video, alcohols are the main focus, with various examples provided to demonstrate their nomenclature and structural features. The script discusses the naming conventions for different alcohols, such as methyl alcohol and ethyl alcohol, which are essential for understanding the chemistry of these compounds.
💡Methyl Alcohol
Methyl alcohol, also known as methanol, is a simple alcohol with one carbon atom in its carbon chain. It is used as a basic example in the video to illustrate the common naming conventions for alcohols. Methyl alcohol is a key concept as it sets the stage for more complex alcohol structures and their names discussed later in the video.
💡Ethyl Alcohol
Ethyl alcohol, or ethanol, is a common alcohol with two carbon atoms in its chain. It is widely known as the type of alcohol found in alcoholic beverages. In the video, ethyl alcohol serves as another fundamental example, highlighting how the increase in carbon chain length affects the naming of alcohols.
💡Isopropyl Alcohol
Isopropyl alcohol is an alcohol with an isopropyl group attached to the hydroxyl group. It is distinguished from other alcohols by its branched structure. The video uses isopropyl alcohol to demonstrate how branched alcohols are named, emphasizing the importance of the position of the hydroxyl group in determining the alcohol's name.
💡Tert-Butyl Alcohol
Tert-butyl alcohol is a specific type of alcohol where the hydroxyl group is attached to a tertiary carbon atom within a butane molecule. The term 'tert' indicates that the carbon is attached to three other carbon atoms. In the video, tert-butyl alcohol is used to illustrate the naming of tertiary alcohols and the significance of carbon chain numbering.
💡IUPAC Nomenclature
IUPAC (International Union of Pure and Applied Chemistry) nomenclature is a systematic method of naming chemical compounds. The video script delves into IUPAC nomenclature rules for alcohols, such as 2-propanol and 2-methyl-2-propanol, to show how the position of the hydroxyl group and any substituents dictate the alcohol's name.
💡Hydroxyl Group
The hydroxyl group is a functional group consisting of an oxygen atom bonded to a hydrogen atom (-OH). It is central to the definition of alcohols and is the basis for their nomenclature. The script explains how the position of the hydroxyl group on the carbon chain influences the naming of alcohols, as seen with 2-propanol and 3,4-hexanediol.
💡Substituents
Substituents are atoms or groups of atoms that replace hydrogen atoms in a hydrocarbon molecule. In the context of the video, substituents such as methyl or ethyl groups are attached to the main carbon chain of the alcohol, affecting its name. The script uses examples like 2-bromo-4-chloro-3-pentanol to explain how substituents are named and ordered in IUPAC nomenclature.
💡Condensed Structure
A condensed structure is a shorthand way of representing organic molecules where carbon-carbon single bonds are omitted for simplicity. The video script mentions converting a condensed structure into a line structure for easier naming, as seen with the example of 1-butanol with a methoxy group.
💡Cyclohexanol
Cyclohexanol is an alcohol with a ring structure consisting of six carbon atoms. The video uses cyclohexanol to explain how alcohols with ring structures are named, emphasizing the importance of numbering to indicate the position of substituents, such as in 3-ethyl cyclohexanol.
💡Functional Group Priority
In organic chemistry, functional groups determine the priority in naming compounds. The video script explains that the hydroxyl group, being the functional group of alcohols, takes precedence over other substituents like halogens when naming, as illustrated with the example of 4-bromo-1-pentanol.
Highlights

Introduction to naming alcohols using basic examples.

Common name for CH3OH is methyl alcohol, also known as methanol.

Common name for CH3CH2OH is ethyl alcohol, also known as ethanol.

Isopropyl alcohol has an isopropyl group attached to the OH group.

tert-Butyl alcohol nomenclature and structure.

Introduction to IUPAC nomenclature for isopropyl alcohol: 2-propanol.

IUPAC naming for tert-butyl alcohol: 2-methyl-2-propanol.

Naming alcohols with five carbon chains and the OH group on carbon 2: 2-pentanol.

Naming molecules with two hydroxyl groups: diols, such as 3,4-hexanediol.

Priority of functional groups in naming: alcohol over alkyl halide.

Naming alcohols with additional substituents: 2-bromo-4-chloro-3-pentanol.

Converting condensed structures to line structures for naming.

Example of naming 1-butanol with a methoxy group: 4-methoxy-1-butanol.

Naming alcohols on a ring structure: cyclopentanol.

Numbering substituents on ring structures for naming: 3-ethylcyclohexanol.

Example of naming a compound with multiple substituents on a ring: 2-ethyl-5-methylcyclohexanol.

Transcripts

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Alcohol NomenclatureIUPAC RulesChemical NamesMethyl AlcoholEthanolIsopropyl AlcoholTert-Butyl AlcoholOrganic ChemistryEducational GuideNaming MoleculesChemical Education