Nitrogen (One atom N only)

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aci-nitro compounds: See azinic acids; see also aci-nitro compounds following nitro compounds.


Imines derived from aldehydes : RCH=NR. GNOC Recom. R-5.4.3. E.g. EtCH=NH, PhCH=NMe.


Oximes of aldehydes: RCH=NOH. GNOC Recom. R-


O-Alkyl hydroxylamines (with or without substitution on N) : R'ONR2 (R' not equal to H). NOC Rules C-841.2, C-841.4.

alkylideneamino carbenes: See under nitrile ylides.

alkylideneaminoxyl radicals:

Radicals having the structure R2C=N-O.. Synonymous with iminoxyl radicals.

alkylideneaminyl radicals:

Radicals having the structure R2C=N.. Synonymous with iminyl radicals.

amic acids:*

Carbamoyl carboxylic acids, i.e. compounds containing a carboxy and a carboxamide group. E.g. 5-carbamoylnicotinic acid.

Note. In systematic nomenclature replacement of the "-ic" suffix of a dicarboxylic acid by "-amic" is limited to dicarboxylic acids that have a trivial name. NOC C-431. E.g. HOC(=O)CH2C(=O)NH2 malonamic acid (2-carbamoylacetic acid).


1. Derivatives of oxoacids RkE(=O)l(OH)m (l not equal to 0) in which an acidic hydroxy group has been replaced by an amino or substituted amino group. Chalcogen replacement analogues are called thio-, seleno- and telluro-amides. Compounds having one, two, or three acyl groups on a given nitrogen are generically included and may be designated as primary, secondary and tertiary amides, respectively. See also e.g. carboxamides , lactams, peptides, phosphoramides, sulfonamides. NOC Rule C-821. E.g. PhC(=O)NH2 benzamide, CH3S(=O)2NMe2 N,N-dimethylmethanesulfonamide, [RC(=O)]2NH secondary amides (see imides), [RC(=O)]3N tertiary amides, PhP(=O)(OH)NH2 phenylphosphonamidic acid.

Note 1. Amides with -NH2, -NHR, and -NR2 groups should not be distinguished by means of the terms primary, secondary, and tertiary. NOC Rule C-824, footnote.

Note 2. Derivatives of certain acidic compounds RnE(OH)m, where E is not carbon (e.g. sulfenic acids, RSOH, phosphinous acids, R2POH) having the structure RnE(NR2)m may be named as amides but do not belong to the class amides proper. NOC Rules C-641.8, D-5.21. E.g. CH3CH2SNH2 ethanesulfenamide or ethylsulfanylamine.

2. The term applies also to metal derivatives of ammonia and amines, in which a cation replaces a hydrogen atom on nitrogen. Such compounds are also called azanides. RNRI Rule RC-83.1.5. E.g. LiN(i-Pr)2 lithium diisopropylamide, synonym lithium diisopropylazanide.


Compounds formally derived from ammonia by replacing one, two, or three hydrogen atoms by hydrocarbyl groups, and having the general structures RNH2 (primary amines), R2NH (secondary amines), R3N (tertiary amines). NOC Rule C-811.2.

amine oxides:*

Compounds derived from tertiary amines by the attachment of one oxygen atom to the nitrogen atom: R3N+-O-. NOC Rule C-843. By extension the term includes the analogous derivatives of primary and secondary amines.

amine ylides: Synonymous with ammonium ylides.

aminimides: An undesirable synonym for amine imides. See under ylides.

aminium ions:

Cations HR3N+ formed by hydronation of an amine R3N. RNRI Rule RC- "Non-quaternary ammonium ions" is a synonymous term. E.g. prolinium, PhN+HMe 2 N,N-dimethylanilinium.

Note. If a class X can be hydronated to Xium ions the class Xium ions commonly includes the derivatives formed by the replacement of the added hydron with a hydrocarbyl group. Aminium ions form an exception, made possible by the availability of the class name ammonium ions. See also onium compounds.

aminiumyl radical ions:

Radicals cations, R3N.+, derivable from aminium ions, R3NH+, by removal of a hydrogen atom. Aminiumyl radical ions are, except for H3N.+, synonymous with the ammoniumyl radical ions. As the term ammonium is well known, ammoniumyl radical ions is the more desirable class name. Cf. ammoniumyl radical ions. RNRI Rule RC-85-3.1.

amino radicals: A non-IUPAC term for aminyl radicals.

aminooxyl radicals:

A spelling for aminoxyl radicals used in NOC (NOC Rules C-841.2, C-81.1). Aminoxyl radicals is now preferred. RNRI Rule RC-81.2.4.


The anion H2N-O-, aminoxide, and its N-hydrocarbyl derivatives R2N-O-; formally derived from hydroxylamines, R2NOH, by removing a hydron from the hydroxy group. RNRI Rule RC- E.g. (CH3)2N-O- dimethylaminoxide.

aminoxyl radicals:*

Compounds having the structure R2NO. [2head arrow] R2N.+-O- ; they are radicals derived from hydroxylamines by removal of the hydrogen atom from the hydroxy group, and are in many cases isolable. RNRI Rule RC-81.2.4. The synonymous terms "nitroxyl radicals" and "nitroxides" erroneously suggest the presence of a nitro group; their use is not desirable. E.g. (ClCH2)N-O. bis(chloromethyl)aminoxyl.

aminyl oxides: Obsolete term for aminoxyl radicals.

aminyl radicals:*

The nitrogen-centered radical H2N., formally derived by the removal of a hydrogen atom from ammonia, and its hydrocarbyl derivatives R2N.. NOC Rule C-81.1. RNRI Rule RC-81.1.2.

aminylenes:* See nitrenes.

aminylium ions:* See nitrenium ions.

ammonium compounds: See onium compounds.

ammonium ylides:

1,2-Dipolar compounds of general structure R3N+-C-R2. See also ylides.

ammoniumyl radical ions:

H3N.+ and its hydrocarbyl derivatives. RNRI RC-85.2. E.g. (CH3)3 N.+ trimethylammoniumyl, PhN.+H2 phenylammoniumyl or benzenaminiumyl.


A term for the subclass of Schiff bases R2C=NR', where R' = N-phenyl or substituted phenyl group. Thus N-phenyl imines.


1. Compounds derived from oxoacids RkE(=O)l(OH) m (l not equal to 0) by replacing an -OH group by the -NHPh group or derivative formed by ring substitution; N-phenyl amides. NOC Rule C-641.8. See amides. E.g. CH3C(=O)NHPh acetanilide.

2. Salts formed by replacement of a nitrogen-bound hydron of aniline by a metal or other cation. E.g. NaNHPh sodium anilide.

azinic acids:*

Derivatives of the parent structure H2N+(O-)OH, (GNOC Recom. R-5.3.2) of which the alkylidene derivatives, R2C=N+(O-)OH (tautomers of nitroalkanes), are the most commonly encountered. The alkylideneazinic acids are known as nitronic acids or, synonymously as aci-nitro compounds. E.g. CH2=N+(O-)OH methylideneazinic acid.

azo ylides: See azomethine imides.


Compounds having the structure RN=CR2 (R not equal to H). NOC Rule C-815.3. Many consider the term to include the compounds RN=CRH (R not equal to H), thus making azomethines synonymous with Schiff bases. Cf. imines.

azomethine oxides: Synonymous with nitrones.

azomethine ylides:

1,3-Dipolar compounds having the structure R2C--N+(R)=CR2 [2head arrow] R2C=N+(R)C-R2. See also ylides.

azonic acids:*

N-Hydrocarbyl derivatives of the parent structure HN+(O-)(OH)2. GNOC Recom. R-3.3, Table VII. Cf. phosphonic acids.


Salts or esters of carbamic acid, H2NC(=O)OH, or of N-substituted carbamic acids: R2NC(=O)OR', (R' = hydrocarbyl or a cation). The esters are often called urethanes or urethans, a usage that is strictly correct only for the ethyl esters.

carbinolamines: An obsolete term for hemiaminals.


In systematic nomenclature, the suffix -carbonitrile is used to name compounds RC[triple bond]N where the suffix includes the carbon atom of the -CN. NOC Rule C-832.2. However carbonitrile is not a class name for nitriles.

carbonyl imides:

1,3-Dipolar compounds having the structure R2C=O+-N-R [2head arrow] R2C+-O-N-R. See also oxonium ylides (2).

carbonyl imines: An undesirable synonym for carbonyl imides . See under ylides.


Amides of carboxylic acids, having the structure RC(=O)NR2. The term is used as a suffix in systematic name formation to denote the -C(=O)NH2 group including its carbon atom. NOC Rule C-821.1.

carbylamines: An obsolete term, which should not be used, for isocyanides. NOC Rule C-833.1.


Salts and esters of cyanic acid, HOC[triple bond]N. NOC Rule C-833.1. E.g. KOCN potassium cyanate, PhOCN phenyl cyanate. Cf. isocyanates.


Salts and C-organyl derivatives of hydrogen cyanide, HC[triple bond]N. NOC Rule C-831.1. GNOC Recom. R- See also isocyanides, nitriles, carbonitriles . E.g. CH3C[triple bond]N methyl cyanide (acetonitrile), NaCN sodium cyanide, PhC(=O)CN benzoyl cyanide.


Alcohols substituted by a cyano group, most commonly, but not limited to, examples having a cyano and a hydroxy group attached to the same carbon atom, formally derived from aldehydes or ketones by the addition of hydrogen cyanide. An individual cyanohydrin can systematically be named as a hydroxy nitrile. See under halohydrins. E.g. (CH3)2C(OH)C[triple bond]N 'acetone cyanohydrin' (2-hydroxy-2-methylpropanenitrile), HOCH2CH2C[triple bond]N 'ethylene cyanohydrin' (3-hydroxypropanenitrile).


Compounds having two acyl groups substituted on ammonia or a primary amine: acyl-NR-acyl. They are also known as secondary amides and, especially the cyclic examples derived from diacids, as imides. NOC Rule C-826. E.g. [RC(=O)]2NR, RS(=O) 2NHC(=O)R.


Alkenylamines; by usage the term refers specifically to vinylic amines, which have the structure R2 NCR=CR2.


1. Compounds having the structure RON=C:. NOC Rule C-833.1; GNOC Recom. R- So called because fulminic acid (actually HC[triple bond]N+-O- formonitrile oxide) was previously considered to be HON=C:.

2. Salts of fulminic acid. E.g. Na+[-C[triple bond]N+-O-].


[alpha]-Amino alcohols, improperly called carbinolamines (the adducts of ammonia, or of primary or secondary amines to the carbonyl group of aldehydes and ketones): R2C(OH)(NR2) . Compounds of structure R2C(OR')NR2 (R' not equal to H) are hemiaminal ethers, or [alpha]-amino ethers. See alcohols, aminals, ethers.

hydroxamic acids:*

Compounds, RC(=O)NHOH, derived from oxoacids RkE(=O)l(OH)m (l not equal to 0) by replacing -OH by -NHOH, and hydrocarbyl derivatives thereof. NOC Rule 451.3. Specific examples are preferably named as N-hydroxy amides. NOC Rules C-841.3, C-841.4; GNOC Recom. R-

hydroximic acids:*

Compounds derived from oxoacids RkE(=O)l (OH)m (l not equal to 0) by replacing =O by =NOH (=NOR), as in carbohydroximic acids, RC(OH)=NOH, (NOC Rule C-451.1) and sulfonohydroximic acids, RS(=O)(=NOH)OH. GNOC Recom. R- Table 14.


Hydroxylamine, H2N-OH, and its hydrocarbyl derivatives. NOC Rule C-841. See also hydroxamic acids, oximes.


1. Diacyl derivatives of ammonia or primary amines, especially those cyclic compounds derived from diacids. NOC Rule C-827. E.g.

2. In additive nomenclature, in which imide is analogous to oxide, the term is used to name compounds of the type R3Y+-N-R (Y = N, P) and R2Z+-N-R (Z = O, S, Se, Te), which are the products of formal attachment of an RN= group to N, P, O, S, Se, Te. E.g. amine imides, azomethine imides.

3. Salts having the anion RN2-. RNRI Rule RC-

imidic acids:*

Compounds derived from oxoacids RkE(=O)l(OH)m (l not equal to 0) by replacing =O by =NR; thus tautomers of amides. In organic chemistry an unspecified imidic acid is generally a carboximidic acid, RC(=NR)OH. NOC Rule C-451.1; GNOC Recom. R-5.7.2. E.g. RS(=NH)2OH a sulfonodiimidic acid. Cf. imino acids.


Analogues of cyclic acid anhydrides in which =O has been replaced by =NR and -O- by -NR-. Cf. diamidides.


A non-IUPAC term for nitrenes used in the Chemical Abstracts Service index nomenclature. RNRI RC-, footnote.

imidonium ions: A term, which is not recommended, for nitrenium ions. GTPOC

imidoyl carbenes:

Carbenes having the structure RC(=NR)C:-R. Imidoyl is a shortened but imprecise term for carboximidoyl, RC(=NH)-.


1. Compounds having the structure RN=CR2 (R = H, hydrocarbyl). Thus analogues of aldehydes or ketones, having NR doubly bonded to carbon; aldimines have the structure RCH=NR, ketimines have the structure R'2C=NR (R' not equal to H). Imines include azomethines and Schiff bases. Imine is used as a suffix in systematic nomenclature to denote the C=NH group excluding the carbon atom. NOC Rule C-815.3. GNOC Recom. R-5.4.3. See also azomethines, Schiff bases.

2. An obsolete term for azacycloalkanes.

iminium compounds:*

Salts in which the cation has the structure R2C=N+R2. Thus N-hydronated imines and their N-substituted derivatives. RNRI Rule RC- The synonymous terms imonium compounds and immonium compounds are irregularly formed and should not be used. Cf. quaternary ammonium compounds.

imino acids:

1. An obsolete term, which should not be used, for imidic acids .

2. Any carboxylic acid having an imino substituent, HN=, replacing two hydrogens. A shortened form of imino carboxylic acid.

3. Obsolescent term for azaalkanoic acids and azacycloalkane-2-carboxylic acids. E.g. proline

imino carbenes:

This term systematically means carbenes bearing an imino or N-substituted imino group, RN=, somewhere in the molecule. E.g. R-C:-CH2C(=NR)R. It is listed here in order to warn against its misuse for alkylideneamino carbenes. Cf. carbenes, nitrile ylides.

iminooxy/iminoxy radicals:

This term has improperly been used for alkylideneaminoxyl radicals, also called iminoxyl radicals: R2C=N-O.. Its use is strongly discouraged. Cf. aminoxyl radicals, iminyl radicals.

iminoxyl radicals:*

Synonymous with alkylideneaminoxyl radicals. The term can be regarded as a contraction of iminyloxyl radicals. RNRI RC-81.2.4.

iminyl carbenes: See under nitrile ylides.

iminyl radicals:

Radicals having the structure R2C=N. . A contraction of alkaniminyl radicals. A synonymous term is alkylideneaminyl radicals. RNRI Rule RC- Cf. aminyl radicals . E.g. MeCH=N. ethaniminyl.

iminylium ions:

Cations having the structure R2C=N+. A contraction of alkaniminylium ions. Alkylideneaminylium ions is a synonymous term. RNRI Rule RC- A subclass of nitrenium ions.


The isocyanic acid tautomer, HN=C=O, of cyanic acid, HOC[triple bond]N and its hydrocarbyl derivatives: RN=C=O. NOC Rule C-833.1.


The isomer HN+[triple bond]C- of hydrocyanic acid, HC[triple bond]N, and its hydrocarbyl derivatives: RNC (RN+ [triple bond]C-). NOC Rule C-833.1.

isonitriles: An obsolete term, which should not be used, for isocyanides. NOC Rule C-833.1.

isonitroso compounds:

An obsolete term for oximes, based on the fact that compounds with a nitroso group, -N=O, bonded to a -CR2H group readily tautomerise to oximes.


The imidic acid tautomer of urea, H2NC(=NH)OH, and its hydrocarbyl derivatives. NOC Rule C-972.


Compounds having the structure R2C=C=NR. Thus imino analogues of ketenes.


Compounds having the structure R2C=NR' (R not equal to H). GNOC Recom. R-5.4.3. See imines.


Oximes of ketones, R 2C=NOH (R not equal to H). GNOC Recom. R-


Cyclic amides of amino carboxylic acids, having a 1-azacycloalkan-2-one structure, or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring. NOC Rule C-475.1. E.g.


Tautomeric forms of lactams, having an endocyclic carbon-nitrogen double bond. Thus, cyclic carboximidic acids. NOC Rule C-475.1. E.g.


1. The neutral compound HN: having univalent nitrogen, and its derivatives RN:. Aminylenes is a recognised but less widely used synonym. RNRI Rule RC- NOC Rule C-81.2. Other names that have been used include aminediyls, imidogens, azenes. They may exist in either a singlet or a triplet electronic state (four spin-paired electrons, or two spin-paired and two with parallel spins, respectively). Cf. carbenes. E.g. CH3N: methylnitrene.

2. Until the 1960s, nitrenes had a totally different meaning: analogues of nitrones in which the double-bonded oxygen is replaced by double-bonded carbon, thus azomethine ylides.

nitrenium ions:*

The cation H2N:+ and its N-hydrocarbyl derivatives R2N:+, in which the nitrogen has a positive charge, and two unshared electrons. A synonymous but less widely used term is aminylium ions. RNRI Rule RC- The alkylidene derivatives of H2N:+ , R2C=N:+ , still belong to the class nitrenium ions, but are more precisely designated by the term iminylium ions .


Compounds having the structure RC[triple bond]N; thus C-substituted derivatives of hydrocyanic acid, HC[triple bond]N. NOC Rule C-831. In systematic nomenclature, the suffix nitrile denotes the triply bound [triple bond]N atom, not the carbon atom attached to it. NOC Rule C-832.1. GNOC Recom. R- See also, carbonitriles, cyanides, isocyanides.

nitrile oxides:*

Ylides having the structure RC[triple bond]N+-O- [2headed arrow] RC-=N+=O. NOC Rule C-834.1. See also dipolar compounds.

nitrile sulfides:

Sulfur analogues of nitrile oxides: RC[triple bond]N+-S- [2headed arrow] RC-=N+=S. See also dipolar compounds.

nitrile ylides:

1,3-Dipolar compounds having the structure RC[triple bond]N+-C-R2 [2headed arrow] RC-=N+=CR2 [2headed arrow] RC+=NC-R2 [2headed arrow] RC:-N=CR2. The uncharged canonical form C:-N=CR2 is called an alkylidene- (or hydrocarbylidene-) amino carbene; the name iminyl carbene is incorrect because iminyl is not a recognised prefix for -N=CR2. See also carbenes, dipolar compounds.

nitrilium betaines:

Derivatives of nitriles having the general structure R-C[triple bond]N+-Y-. A subclass of 1,3-dipolar compounds including nitrile imides, nitrile oxides, nitrile sulfides and nitrile ylides.

nitrilium ions:*

Cations derived formally by attachment of one hydron to the nitrogen atom of a nitrile and hydrocarbyl derivatives thereof. E.g. PhC[triple bond]N+H [2headed arrow] PhC+=NH benzonitrilium. RNRI Rule RC-

nitro compounds:*

Compounds having the nitro group, -NO2 (free valence on nitrogen), which may be attached to carbon, nitrogen (as in nitramines), or oxygen (as in nitrates), among other elements (in the absence of specification, C-nitro compounds are usually implied). NOC Rule C-852.1. See also dipolar compounds.

aci-nitro compounds:

A class name for hydrocarbylideneazinic acids, R2C=N+(-O-)OH. The use of aci-nitro as a prefix in systematic nomenclature to name specific compounds (NOC Rule C-852.2) is abandoned. GNOC Recom. R-5.3.2, footnote. See also azinic acids.

nitrogen mustards: See mustards.

nitrogen ylides: See ylides.


The N-oxides of imines, that have the structure R2C=N+(O-)R' (R' not equal to H). NOC Rule C-842.3. Synonymous with azomethine oxides. N-Oxides R2C=N+(O-)H may be included. See also dipolar compounds.

nitronic acids: See azinic acids.

nitroso compounds:*

Compounds having the nitroso group, -NO, attached to carbon, or to another element, most commonly nitrogen or oxygen. See nitrosamines. NOC Rule C-851.

nitrosolic acids:

Compounds having the structure RC(=NOH)NO.


Nitroxide is the parent name used by Chemical Abstracts Service for H2N-O.. E.g. (ClCH2)2N-O. bis(chloromethyl) nitroxide. The IUPAC name is bis(chloromethyl)aminoxyl. Nitroxides should not be used as a class name for aminoxyl radicals. See aminoxyl radicals.

nitroxyl radicals: See aminoxyl radicals.

oxime O-ethers:*

O-Hydrocarbyl oximes R2C=NOR' (R' not equal to H). NOC Rule C-842.2.


Compounds of structure R2C=NOH derived from condensation of aldehydes or ketones with hydroxylamine. NOC Rule C-842.1. GNOC Recom. R- Oximes from aldehydes may be called aldoximes; those from ketones may be called ketoximes.

pseudoureas: An obsolescent synonym for isoureas.

quaternary ammonium compounds:*

Derivatives of ammonium compounds, NH4+ Y-, in which all four of the hydrogens bonded to nitrogen have been replaced with hydrocarbyl groups. Compounds having a carbon-nitrogen double bond (i.e. R2C=N+R2 Y-) are more accurately called iminium compounds. See under onium compounds. E.g. [(CH3)4N]+ OH- tetramethylammonium hydroxide.

quinonimines/quinone imines:*

Imines derived from quinones by replacement of one or both oxygens by =NR. The term may include both types unless the infix mono or di is included. NOC Rule C-815.3 E.g.o-benzoquinone diimine


Mono- or dioximes of quinones; quinone monooximes are tautomeric with nitrosophenols. Cf. oximes.

Schiff bases, Schiff's bases:*

Imines bearing a hydrocarbyl group on the nitrogen atom: R 2C=NR' (R' not equal to H). NOC Rule C-815.3. Considered by many to be synonymous with azomethines. See also azomethines.


N-Acyl or N,N'-diacyl ureas. NOC Rule C-971.2.

urethanes (urethans):

An alternative term for the compounds R2NC(=O)OR' (R' not equal to H), esters of carbamic acids, R2NC(=O)OH, in strict use limited to the ethyl esters, but widely used in the general sense. E.g. 'polyurethane resins'. Cf. carbamates


N,N-Disubstituted alk-1-yn-1-amines, RC[triple bond]CNR2. By usage, restricted to this type of acetylenic amine. Cf. enamines.

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