Senyawa Karbon Turunan Alkana • Part 8: Tatanama Alkil Halida / Haloalkana

Summary

In this educational video, the speaker discusses the IUPAC and common naming conventions for alkyl halides, a key topic in organic chemistry. The video explores the principles of naming these compounds, including how halogen atoms (chlorine, bromine, fluorine, iodine) are treated as branches in the molecule's structure. It covers the steps of selecting the longest chain, numbering atoms to give halogens the lowest possible numbers, and applying prefixes like 'chloro', 'bromo', 'fluoro', and 'iodo'. Detailed examples are provided to clarify the process, helping viewers better understand and apply these rules in practice.

Takeaways

• 😀 Understanding Alkyl Halides: Alkyl Halides (haloalkanes) are derived from alkanes with a halogen (Cl, Br, F, I) replacing a hydrogen atom.
• 😀 Two Naming Systems: There are two main naming conventions for alkyl halides: IUPAC and common naming. IUPAC names involve 'haloalkanes,' while common names use simpler terms like methyl chloride or ethyl bromide.
• 😀 IUPAC Nomenclature: The IUPAC system requires the halogen to be considered a branch, and the longest carbon chain attached to the halogen becomes the main chain.
• 😀 Common Nomenclature: In common names, alkyl groups are named first (e.g., methyl, ethyl), followed by the halogen (e.g., chlorine, bromine).
• 😀 Branch Naming: For more complex alkyl halides, identifying and naming the alkyl branches (e.g., methyl, ethyl, isobutyl) is crucial.
• 😀 Halogen Naming: In IUPAC, halogens are named as fluoro (F), chloro (Cl), bromo (Br), and iodo (I), depending on the halogen attached to the molecule.
• 😀 Prioritizing the Halogen: When numbering the carbon chain, priority is given to the halogen. The carbon attached to the halogen must have the smallest number possible.
• 😀 Multiple Halogens: If there are multiple halogen substituents, they are named in alphabetical order (e.g., 'fluoro' before 'chloro' even though F is earlier in the alphabet than C in the English language).
• 😀 Numbering the Carbon Chain: When multiple substituents (alkyl or halogen groups) are present, numbering should ensure the smallest possible numbers for all attached groups.
• 😀 Example Naming: The IUPAC name for a complex alkyl halide involves a detailed step-by-step approach, such as naming the main chain, identifying the halogen groups, and applying correct prefixes for multiple halogen atoms.

Q & A

What is the basic concept of IUPAC naming for alkyl halides?

In IUPAC naming, alkyl halides are named by identifying the longest carbon chain as the main chain and numbering it to give the halogen the lowest possible number. The halogen is treated like a branch, named as fluoro, chloro, bromo, or iodo, depending on the halogen present.

What is the difference between IUPAC and common names for alkyl halides?

IUPAC names follow systematic rules for naming based on the longest chain and position of substituents, while common names are simpler and often based on the alkyl group and halogen (e.g., methyl chloride instead of chloromethane).

How do you determine the longest chain in an alkyl halide molecule?

The longest continuous chain of carbon atoms is identified as the main chain. This chain should include the carbon attached to the halogen. Other possible chains or branches should be considered only as substituents.

What is the priority order for numbering the carbon chain in alkyl halides?

The chain should be numbered such that the halogen (fluoro, chloro, bromo, or iodo) gets the lowest possible number. If multiple halogens are present, prioritize fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) in that order.

How are multiple halogen substituents handled in the IUPAC naming system?

If there are multiple halogen substituents, each halogen is listed with a prefix (e.g., di-, tri-) and the positions are numbered. The halogens are named alphabetically in the final name, regardless of their order in the structure.

Why is 'chloro' written with a 'C' in the IUPAC naming convention, even though it starts with 'K' in Indonesian?

In IUPAC nomenclature, 'chloro' is considered an English term, where it starts with 'C'. Despite the Indonesian usage of 'kloro' with a 'K', the proper IUPAC term starts with 'C' for alphabetical ordering.

What is the rule for naming alkyl groups attached to the main chain in alkyl halides?

Alkyl groups attached to the main chain are named as simple alkyl groups (e.g., methyl, ethyl, propyl) and are numbered based on their position on the chain. If there are multiple alkyl groups, their names are listed alphabetically.

How are multiple halogen atoms of the same type (e.g., two chlorines) named in IUPAC nomenclature?

When multiple halogen atoms of the same type are present, the prefix 'di-' is used to indicate two halogen atoms, 'tri-' for three, and so on. For example, two chlorines would be called 'dichloro'.

What should you do when naming an alkyl halide with both alkyl and halogen branches?

In cases with both alkyl and halogen branches, the numbering starts by prioritizing halogens (F > Cl > Br > I). After the halogens are numbered, alkyl groups are named and numbered, and the final name is written following the order of prefixes for halogens and alkyl groups.

Can you explain how to name a complex alkyl halide using the IUPAC system with multiple substituents?

To name a complex alkyl halide, first identify the longest chain of carbon atoms as the main chain. Number the chain to give halogen atoms the lowest possible numbers. Then, name and number the alkyl and halogen substituents, ensuring alphabetical order for multiple types of substituents. For example, '2-bromo-3-chloro-4-methylpentane'.