How many alkyl substituents does -ethyl- -methylaniline have? Explain the following substituents briefly and choose correct one.
Select one:
A. One.
B. two.
C. three.
D. eight.
E. none.
The Correct Answer and Explanation is:
Let’s carefully analyze the compound name ethyl-methylaniline and determine how many alkyl substituents it contains.
Step 1: Understand the compound name
- Aniline is the base compound here. Aniline is a benzene ring with an amino group (-NH₂) attached.
- Ethyl- and methyl- are substituents attached to the benzene ring.
- The name ethyl-methylaniline suggests the benzene ring has two alkyl substituents: one ethyl group (-CH₂CH₃) and one methyl group (-CH₃), along with the amino group (-NH₂).
Step 2: Define what is an alkyl substituent
- An alkyl substituent is a side chain derived from an alkane by removal of one hydrogen atom. Common alkyl groups include:
- Methyl (–CH₃)
- Ethyl (–CH₂CH₃)
- Propyl, butyl, etc.
- These are carbon-based substituents attached to the parent compound.
Step 3: Identify alkyl substituents in ethyl-methylaniline
- Ethyl group is an alkyl substituent.
- Methyl group is another alkyl substituent.
- The amino group (-NH₂) is not an alkyl substituent; it is an amine substituent.
Thus, the compound contains two alkyl substituents: ethyl and methyl.
Explanation of substituents briefly:
- Ethyl (-CH₂CH₃): A two-carbon alkyl group derived from ethane by removing one hydrogen atom. It is larger than methyl and adds more steric bulk to the molecule.
- Methyl (-CH₃): The simplest alkyl substituent, derived from methane. It is a one-carbon group attached to the benzene ring.
- Amino (-NH₂): Not an alkyl substituent; it is a functional group containing nitrogen, characteristic of aniline.
Conclusion:
Since ethyl-methylaniline has two alkyl substituents (ethyl and methyl), the correct answer is:
B. two.
Further explanation (300 words):
In organic chemistry, the naming of compounds (IUPAC nomenclature) helps us identify how many and what types of substituents are attached to a parent structure. Here, the parent compound is aniline, which is benzene with an amino group (-NH₂). When we see the name ethyl-methylaniline, it indicates that two other substituents—ethyl and methyl—are attached to the benzene ring along with the amino group.
The key to answering the question about how many alkyl substituents exist is to understand what qualifies as an alkyl substituent. Alkyl groups are hydrocarbon chains or branches derived from alkanes by removing one hydrogen atom. Common alkyl groups include methyl (-CH₃), ethyl (-CH₂CH₃), propyl (-CH₂CH₂CH₃), and so forth.
In ethyl-methylaniline, the ethyl group consists of two carbon atoms attached as a side chain, and the methyl group is a single carbon attached directly to the ring. Both are classic alkyl substituents. On the other hand, the amino group (-NH₂), which defines aniline, is not an alkyl substituent but an amine functional group with nitrogen. Therefore, it does not count towards the number of alkyl substituents.
Since only the ethyl and methyl groups qualify, there are two alkyl substituents in this compound.
To summarize:
- Ethyl = 1 alkyl substituent
- Methyl = 1 alkyl substituent
- Amino = not alkyl
Total alkyl substituents = 2
Thus, the correct choice is B. two.
If you’d like, I can help further with similar nomenclature or more complex substituent explanations!