Q.(A) Write the structure of phenylmethanamine.

$(CH_3)_3C-NH_2$ (tert-butylamine) is named 2-methylpropan-2-amine by IUPAC rules.

To name an amine by IUPAC substitutive nomenclature, the longest carbon chain containing the carbon bearing the $-NH_2$ group is selected as the parent, and the suffix '-amine' is added with a locant, while other substituents are cited as prefixes with their own locants.

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CH₂=CH–CH₂–NH–CH₃ is named as a propene chain bearing an amine at C1 and an N-methyl substituent, giving N-methylprop-2-en-1-amine.

Structure: CH₂=CH–CH₂–NH–CH₃

1. Identify the parent chain: the longest carbon chain containing the –NH– nitrogen's point of attachment is the 3-carbon allyl chain, CH₂=CH–CH₂–, which as a substituted amine is named as prop-2-en-1-amine (double bond between C2–C3, amine at C1).
2. The nitrogen carries an extra methyl substituent (–CH₃) instead of a second hydrogen, so this substituent is cited with the italic locant N- to show it is on nitrogen, not on the carbon chain: N-methyl.
3. Combine: N-methylprop-2-en-1-amine. …

N,N-dimethylethanamine: $CH_3CH_2-N(CH_3)_2$ (both N-H's of ethanamine replaced by methyl groups).

'Ethanamine' is the IUPAC name for ethylamine, $CH_3CH_2-NH_2$. The prefix 'N,N-dimethyl' means two methyl groups replace the two hydrogens on the nitrogen atom itself:

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Name the longest carbon chain bearing the -NH- group as the parent "...amine", and cite the second alkyl group on nitrogen with an italic N- locant.

Structure: CH$_3$–CH(CH$_3$)–NH–CH$_3$, i.e. (CH$_3$)$_2$CH–NH–CH$_3$ — this is a secondary amine: an isopropyl group and a methyl group both attached to the same nitrogen.

IUPAC naming for secondary/tertiary amines:

1. Identify the parent chain carrying the nitrogen with the longest carbon skeleton directly bonded to N: here that's the 3-carbon isopropyl fragment, CH$_3$–CH(NH...)–CH$_3$, named as propan-2-amine (amine group on C-2 of propane). …

CH3-CH(NH2)-CH3 is a 3-carbon chain with -NH2 on C2 → propan-2-amine.

The compound CH3-CH(NH2)-CH3 has a parent chain of three carbons (propane) with an amino group -NH2 on the central carbon (position 2). The IUPAC name is formed as propan-2-amine (the -e of propane is dropped before …

The longest carbon chain attached to N (ethyl, 2 carbons) is chosen as the parent 'ethanamine'; the two remaining methyl groups on N are cited as N,N-dimethyl substituents.

C₂H₅–N(CH₃)–CH₃ is a tertiary amine with three groups on nitrogen: one ethyl and two methyl groups. IUPAC naming of amines picks the longest carbon chain bonded to the nitrogen as the parent chain (here, the 2-carbon ethyl group, giving the parent 'ethanamine'), and cites every other group atta …

Pick the longest carbon chain running through the carbon attached to nitrogen, number to give the amine (and thus the N-substituent carbon) the lowest locant, and cite the branch and the two N-methyls as substituents.

The amine nitrogen is bonded to two methyl groups and to a carbon (call it C*) that itself carries: a methyl group, an ethyl group, and continues into a -CH₂-CH₃ chain.

To find the parent chain, take the longest carbon chain running through C* (the carbon bearing the amino group): combining the ethyl branch on one side with the -CH₂-CH₃ continuation on the other side through C* gives a 5-carbon chain (pentane): $CH_3-CH_2-C^*(CH_3)(NMe_2)-CH_2-CH_3$, with C* as carbon 3 of that chain (the methyl group on C* becomes a 3-methyl substituent, and the shorter methyl-only branch is …

CH3–CH(NH2)–CH2–CHO is a 4-carbon chain named as a butanal with an amino substituent, giving 3-aminobutanal.

Since the aldehyde group (–CHO) is the senior (principal) characteristic group, the chain is numbered from the CHO carbon as C1: C1(CHO)–C2(CH2)–C3(CH–NH2)–C4(CH3). The parent chain is b …

The nitrogen carries two ethyl groups and one propyl group attached through its terminal (C1) carbon, giving N,N-diethylpropan-1-amine (written N,N-diethylpropanamine).

C2H5–N(C2H5)–CH2CH2CH3 is a tertiary amine. The longest chain attached to N through a single bond at its end carbon is propyl (3 carbons), so the parent name is propanamine (locant 1 is the default/implied positi …

Number the 3-carbon allyl chain from the end bearing the $-NH-$ group; the double bond is at C2–C3.

The compound is $CH_2{=}CH{-}CH_2{-}NH{-}CH_3$. The parent chain is the 3-carbon chain carrying the principal characteristic group ($-NH-$), i.e. propene: $C1(H_2N\text{-attached})-C2{=}C3$. Numbering to give the amine-bearing carbon the lowest locant: C1 bears the $NHCH_3$ group, and the double bond runs between C2 and C3, so the parent is prop-2-en-1-amine. The extra methyl group on nitrogen is indicated by the italic locant N: N-methyl. …