Functional group

In organic chemistry, functional groups are specific substituents or moieties within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction(s) regardless of the size of the molecule it is a part of.[1][2] This allows for systematic prediction of chemical reactions and behavior of chemical compounds and design of chemical syntheses. Furthermore, the reactivity of a functional group can be modified by other functional groups nearby. In organic synthesis, functional group interconversion is one of the basic types of transformations.

Functional groups are groups of one or more atoms of distinctive chemical properties no matter what they are attached to. The atoms of functional groups are linked to each other and to the rest of the molecule by covalent bonds. For repeating units of polymers, functional groups attach to their nonpolar core of carbon atoms and thus add chemical character to carbon chains. Functional groups can also be charged, e.g. in carboxylate salts (–COO), which turns the molecule into a polyatomic ion or a complex ion. Functional groups binding to a central atom in a coordination complex are called ligands. Complexation and solvation are also caused by specific interactions of functional groups. In the common rule of thumb "like dissolves like", it is the shared or mutually well-interacting functional groups which give rise to solubility. For example, sugar dissolves in water because both share the hydroxyl functional group (–OH) and hydroxyls interact strongly with each other. Plus, when functional groups are more electronegative than atoms they attach to, the functional groups will become polar, and the otherwise nonpolar molecules containing these functional groups become polar and so become soluble in some aqueous environment.

Combining the names of functional groups with the names of the parent alkanes generates what is termed a systematic nomenclature for naming organic compounds. In traditional nomenclature, the first carbon atom after the carbon that attaches to the functional group is called the alpha carbon; the second, beta carbon, the third, gamma carbon, etc. If there is another functional group at a carbon, it may be named with the Greek letter, e.g., the gamma-amine in gamma-aminobutyric acid is on the third carbon of the carbon chain attached to the carboxylic acid group. IUPAC conventions call for numeric labeling of the position, e.g. 4-aminobutanoic acid. In traditional names various qualifiers are used to label isomers, for example, isopropanol (IUPAC name: propan-2-ol) is an isomer of n-propanol (propan-1-ol).

Benzyl acetate - functional groups and moieties
Benzyl acetate has an ester functional group (in red), an acetyl moiety (circled with dark green) and a benzyloxy moiety (circled with light orange). Other divisions can be made.

Table of common functional groups

The following is a list of common functional groups.[3] In the formulas, the symbols R and R' usually denote an attached hydrogen, or a hydrocarbon side chain of any length, but may sometimes refer to any group of atoms.

Hydrocarbons

Functional groups, called hydrocarbyl, that contain only carbon and hydrogen, but vary in the number and order of double bonds. Each one differs in type (and scope) of reactivity.

Chemical class Group Formula Structural Formulae Prefix Suffix Example
Alkane Alkyl R(CH2)nH Alkyl alkyl- -ane Ethan Keilstrich
Ethane
Alkene Alkenyl R2C=CR2 Alkene alkenyl- -ene ethylene
Ethylene
(Ethene)
Alkyne Alkynyl RC≡CR' alkynyl- -yne
Acetylene
(Ethyne)
Benzene derivative Phenyl RC6H5
RPh
Phenyl phenyl- -benzene Cumene-2D-skeletal
Cumene
(Isopropylbenzene)

There are also a large number of branched or ring alkanes that have specific names, e.g., tert-butyl, bornyl, cyclohexyl, etc. Hydrocarbons may form charged structures: positively charged carbocations or negative carbanions. Carbocations are often named -um. Examples are tropylium and triphenylmethyl cations and the cyclopentadienyl anion.

Groups containing halogen

Haloalkanes are a class of molecule that is defined by a carbon–halogen bond. This bond can be relatively weak (in the case of an iodoalkane) or quite stable (as in the case of a fluoroalkane). In general, with the exception of fluorinated compounds, haloalkanes readily undergo nucleophilic substitution reactions or elimination reactions. The substitution on the carbon, the acidity of an adjacent proton, the solvent conditions, etc. all can influence the outcome of the reactivity.

Chemical class Group Formula Structural Formula Prefix Suffix Example
haloalkane halo RX halo- alkyl halide Chloroethane-skeletal
Chloroethane
(Ethyl chloride)
fluoroalkane fluoro RF fluoro- alkyl fluoride Fluoromethane
Fluoromethane
(Methyl fluoride)
chloroalkane chloro RCl chloro- alkyl chloride Chloromethane
Chloromethane
(Methyl chloride)
bromoalkane bromo RBr bromo- alkyl bromide Methyl bromide
Bromomethane
(Methyl bromide)
iodoalkane iodo RI iodo- alkyl iodide Iodomethane
Iodomethane
(Methyl iodide)

Groups containing oxygen

Compounds that contain C-O bonds each possess differing reactivity based upon the location and hybridization of the C-O bond, owing to the electron-withdrawing effect of sp-hybridized oxygen (carbonyl groups) and the donating effects of sp2-hybridized oxygen (alcohol groups).

Chemical class Group Formula Structural Formula Prefix Suffix Example
Alcohol Hydroxyl ROH
Hydroxyl
hydroxy- -ol methanol
Methanol
Ketone Carbonyl RCOR' Ketone -oyl- (-COR')
or
oxo- (=O)
-one Butanone
Butanone
(Methyl ethyl ketone)
Aldehyde Aldehyde RCHO Aldehyde formyl- (-COH)
or
oxo- (=O)
-al acetaldehyde
Acetaldehyde
(Ethanal)
Acyl halide Haloformyl RCOX Acyl halide carbonofluoridoyl-
carbonochloridoyl-
carbonobromidoyl-
carbonoiodidoyl-
-oyl halide Acetyl chloride
Acetyl chloride
(Ethanoyl chloride)
Carbonate Carbonate ester ROCOOR' Carbonate (alkoxycarbonyl)oxy- alkyl carbonate triphosgene
Triphosgene
(bis(trichloromethyl) carbonate)
Carboxylate Carboxylate RCOO
Carboxylate

Carboxylate

carboxy- -oate Sodium acetate
Sodium acetate
(Sodium ethanoate)
Carboxylic acid Carboxyl RCOOH Carboxylic acid carboxy- -oic acid Acetic acid
Acetic acid
(Ethanoic acid)
Ester Ester RCOOR' Ester alkanoyloxy-
or
alkoxycarbonyl
alkyl alkanoate Ethyl butyrate
Ethyl butyrate
(Ethyl butanoate)
Methoxy Methoxy ROCH3 Methoxy methoxy- Anisole
Anisole
(Methoxybenzene)
Hydroperoxide Hydroperoxy ROOH Hydroperoxy hydroperoxy- alkyl hydroperoxide tert-Butyl hydroperoxide
tert-Butyl hydroperoxide
Peroxide Peroxy ROOR' Peroxy peroxy- alkyl peroxide Di-tert-butyl peroxide
Di-tert-butyl peroxide
Ether Ether ROR'
Ether
alkoxy- alkyl ether Diethyl ether
Diethyl ether
(Ethoxyethane)
Hemiacetal Hemiacetal RCH(OR')(OH) Hemiacetal alkoxy -ol -al alkyl hemiacetal
Hemiketal Hemiketal RC(ORʺ)(OH)R' Hemiketal alkoxy -ol -one alkyl hemiketal
Acetal Acetal RCH(OR')(OR") Acetal dialkoxy- -al dialkyl acetal
Ketal (or Acetal) Ketal (or Acetal) RC(ORʺ)(OR‴)R' Ketal dialkoxy- -one dialkyl ketal
Orthoester Orthoester RC(OR')(ORʺ)(OR‴) Orthoester trialkoxy-
Heterocycle Methylenedioxy PhOCOPh Methylenedioxy chemical structure. methylenedioxy- -dioxole 1,3-Benzodioxole
1,2-Methylenedioxybenzene
(1,3-Benzodioxole)
Orthocarbonate ester Orthocarbonate ester C(OR)(OR')(ORʺ)(OR″) Orthocarbonate ester tetralkoxy- tetraalkyl orthocarbonate Tetramethylorthocarbonat
Tetramethoxymethane
Organic acid anhydride Carboxylic anhydride R(CO)O(CO)R' Carboxylic anhydride anhydride Butyric anhydride
Butyric anhydride

Groups containing nitrogen

Compounds that contain nitrogen in this category may contain C-O bonds, such as in the case of amides.

Chemical class Group Formula Structural Formula Prefix Suffix Example
Amide Carboxamide RCONR2 Amide carboxamido-
or
carbamoyl-
-amide acetamide
Acetamide
(Ethanamide)
Amines Primary amine RNH2 Primary amine amino- -amine methylamine
Methylamine
(Methanamine)
Secondary amine R2NH Secondary amine amino- -amine dimethylamine
Dimethylamine
Tertiary amine R3N Tertiary amine amino- -amine trimethylamine
Trimethylamine
4° ammonium ion R4N+ Quaternary ammonium cation ammonio- -ammonium choline
Choline
Imine Primary ketimine RC(=NH)R' Imine imino- -imine
Secondary ketimine Imine imino- -imine
Primary aldimine RC(=NH)H Imine imino- -imine Ethanimine
Ethanimine
Secondary aldimine RC(=NR')H Imine imino- -imine
Imide Imide (RCO)2NR' Imide imido- -imide Succinimide
Succinimide
(Pyrrolidine-2,5-dione)
Azide Azide RN3 Organoazide azido- alkyl azide Phenyl azide
Phenyl azide
(Azidobenzene)
Azo compound Azo
(Diimide)
RN2R' Azo.pngl azo- -diazene Methyl orange
Methyl orange
(p-dimethylamino-azobenzenesulfonic acid)
Cyanates Cyanate ROCN Cyanate cyanato- alkyl cyanate Methyl cyanate
Methyl cyanate
Isocyanate RNCO Isocyanate isocyanato- alkyl isocyanate Methyl isocyanate
Methyl isocyanate
Nitrate Nitrate RONO2 Nitrate nitrooxy-, nitroxy-

alkyl nitrate

Amyl nitrate
Amyl nitrate
(1-nitrooxypentane)
Nitrile Nitrile RCN cyano- alkanenitrile
alkyl cyanide
Benzonitrile
Benzonitrile
(Phenyl cyanide)
Isonitrile RNC isocyano- alkaneisonitrile
alkyl isocyanide

Methyl isocyanide
Nitrite Nitrosooxy RONO Nitrite nitrosooxy-

alkyl nitrite

Amyl nitrite
Isoamyl nitrite
(3-methyl-1-nitrosooxybutane)
Nitro compound Nitro RNO2 Nitro nitro-   Nitromethane
Nitromethane
Nitroso compound Nitroso RNO Nitroso nitroso- (Nitrosyl-)   Nitrosobenzene
Nitrosobenzene
Oxime Oxime RCH=NOH Oxime   Oxime Acetone oxime
Acetone oxime
(2-Propanone oxime)
Pyridine derivative Pyridyl RC5H4N

4-pyridyl group
3-pyridyl group
2-pyridyl group

4-pyridyl
(pyridin-4-yl)

3-pyridyl
(pyridin-3-yl)

2-pyridyl
(pyridin-2-yl)

-pyridine Nicotine
Nicotine
Carbamate ester Carbamate RO(C=O)NR2 Carbamate (-carbamoyl)oxy- -carbamate Chlorpropham
Chlorpropham
(Isopropyl (3-chlorophenyl)carbamate)

Groups containing sulfur

Compounds that contain sulfur exhibit unique chemistry due to their ability to form more bonds than oxygen, their lighter analogue on the periodic table. Substitutive nomenclature (marked as prefix in table) is preferred over functional class nomenclature (marked as suffix in table) for sulfides, disulfides, sulfoxides and sulfones.

Chemical class Group Formula Structural Formula Prefix Suffix Example
Thiol Sulfhydryl RSH Sulfhydryl sulfanyl-
(-SH)
-thiol Ethanethiol
Ethanethiol
Sulfide
(Thioether)
Sulfide RSR' Sulfide group substituent sulfanyl-
(-SR')
di(substituentsulfide
Dimethyl sulfide

(Methylsulfanyl)methane (prefix) or
Dimethyl sulfide (suffix)
Disulfide Disulfide RSSR' Disulfide substituent disulfanyl-
(-SSR')
di(substituentdisulfide
Dimethyl disulfide

(Methyldisulfanyl)methane (prefix) or
Dimethyl disulfide (suffix)
Sulfoxide Sulfinyl RSOR' Sulfinyl group -sulfinyl-
(-SOR')
di(substituentsulfoxide DMSO
(Methanesulfinyl)methane (prefix) or
Dimethyl sulfoxide (suffix)
Sulfone Sulfonyl RSO2R' Sulfonyl group -sulfonyl-
(-SO2R')
di(substituentsulfone Dimethyl sulfone
(Methanesulfonyl)methane (prefix) or
Dimethyl sulfone (suffix)
Sulfinic acid Sulfino RSO2H Sulfinic-acid-2D sulfino-
(-SO2H)
-sulfinic acid Hypotaurine
2-Aminoethanesulfinic acid
Sulfonic acid Sulfo RSO3H Sulfonyl group sulfo-
(-SO3H)
-sulfonic acid Benzenesulfonic acid
Benzenesulfonic acid
Sulfonate ester Sulfo RSO3R' Sulfonic ester (-sulfonyl)oxy-
or
alkoxysulfonyl-
R' R-sulfonate Methyl trifluoromethanesulfonate
Methyl trifluoromethanesulfonate or
Methoxysulfonyl trifluoromethane (prefix)
Thiocyanate Thiocyanate RSCN Thiocyanate thiocyanato-
(-SCN)
substituent thiocyanate Phenyl thiocyanate
Phenyl thiocyanate
Isothiocyanate RNCS Isothiocyanate isothiocyanato-
(-NCS)
substituent isothiocyanate Allyl isothiocyanate
Allyl isothiocyanate
Thioketone Carbonothioyl RCSR' Thione -thioyl-
(-CSR')
or
sulfanylidene-
(=S)
-thione Diphenylmethanethione
Diphenylmethanethione
(Thiobenzophenone)
Thial Carbonothioyl RCSH Thial methanethioyl-
(-CSH)
or
sulfanylidene-
(=S)
-thial
Thiocarboxylic acid Carbothioic S-acid RC=OSH
Thioic S-acid
mercaptocarbonyl- -thioic S-acid Thiobenzoic acid
Thiobenzoic acid
(benzothioic S-acid)
Carbothioic O-acid RC=SOH
Thioic O-acid
hydroxy(thiocarbonyl)- -thioic O-acid
Thioester Thiolester RC=OSR' Thiolester S-alkyl-alkane-thioate S-methyl thioacrylate
S-methyl thioacrylate
(S-methyl prop-2-enethioate)
Thionoester RC=SOR' Thionoester O-alkyl-alkane-thioate
Dithiocarboxylic acid Carbodithioic acid RCS2H
Dithiocarboxylic acid
dithiocarboxy- -dithioic acid Dithiobenzoic acid
Dithiobenzoic acid
(Benzenecarbodithioic acid)
Dithiocarboxylic acid ester Carbodithio RC=SSR' Dithioate -dithioate

Groups containing phosphorus

Compounds that contain phosphorus exhibit unique chemistry due to their ability to form more bonds than nitrogen, their lighter analogues on the periodic table.

Chemical class Group Formula Structural Formula Prefix Suffix Example
Phosphine
(Phosphane)
Phosphino R3P A tertiary phosphine phosphanyl- -phosphane Methylpropylphosphane
Methylpropylphosphane
Phosphonic acid Phosphono Phosphono group phosphono- substituent phosphonic acid Benzylphosphonic acid
Benzylphosphonic acid
Phosphate Phosphate Phosphate group phosphonooxy-
or
O-phosphono- (phospho-)
substituent phosphate Glyceraldehyde 3-phosphate
Glyceraldehyde 3-phosphate (suffix)
Phosphocholine

O-Phosphonocholine (prefix)
(Phosphocholine)
Phosphodiester Phosphate HOPO(OR)2 Phosphodiester [(alkoxy)hydroxyphosphoryl]oxy-
or
O-[(alkoxy)hydroxyphosphoryl]-
di(substituent) hydrogen phosphate
or
phosphoric acid di(substituentester
DNA
O‑[(2‑Guanidinoethoxy)hydroxyphosphoryl]‑l‑serine (prefix)
(Lombricine)

Groups containing boron

Compounds containing boron exhibit unique chemistry due to their having partially filled octets and therefore acting as Lewis acids.

Chemical class Group Formula Structural Formula Prefix Suffix Example
Boronic acid Borono RB(OH)2
Boronic-acid-2D
Borono- substituent
boronic acid
Phenylboronic acid
Phenylboronic acid
Boronic ester Boronate RB(OR)2
Boronate-ester-2D
O-[bis(alkoxy)alkylboronyl]- substituent
boronic acid
di(substituent) ester
Borinic acid Borino R2BOH
Borinic-acid-2D
Hydroxyborino- di(substituent)
borinic acid
Borinic ester Borinate R2BOR
Borinate-ester-2D
O-[alkoxydialkylboronyl]- di(substituent)
borinic acid
substituent ester
2-Aminoethoxydiphenyl borate
Diphenylborinic acid 2-aminoethyl ester
(2-Aminoethoxydiphenyl borate)

Names of radicals or moieties

These names are used to refer to the moieties themselves or to radical species, and also to form the names of halides and substituents in larger molecules.

When the parent hydrocarbon is unsaturated, the suffix ("-yl", "-ylidene", or "-ylidyne") replaces "-ane" (e.g. "ethane" becomes "ethyl"); otherwise, the suffix replaces only the final "-e" (e.g. "ethyne" becomes "ethynyl").[4]

Note that when used to refer to moieties, multiple single bonds differ from a single multiple bond. For example, a methylene bridge (methanediyl) has two single bonds, whereas a methylene group (methylidene) has one double bond. Suffixes can be combined, as in methylidyne (triple bond) vs. methylylidene (single bond and double bond) vs. methanetriyl (three double bonds).

There are some retained names, such as methylene for methanediyl, 1,x-phenylene for phenyl-1,x-diyl (where x is 2, 3, or 4),[5] carbyne for methylidyne, and trityl for triphenylmethyl.

Chemical class Group Formula Structural Formula Prefix Suffix Example
Single bond R• Ylo-[6] -yl
Methyl group
Methyl radical
Double bond R: ? -ylidene
Methylidene
Triple bond R⫶ ? -ylidyne
Methylidyne
Carboxylic acyl radical Acyl R−C(=O)• ? -oyl
Acetyl

See also

References

  1. ^ Compendium of Chemical Terminology (IUPAC "Gold Book") functional group
  2. ^ March, Jerry (1985), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (3rd ed.), New York: Wiley, ISBN 0-471-85472-7
  3. ^ Brown, Theodore (2002). Chemistry: the central science. Upper Saddle River, NJ: Prentice Hall. p. 1001. ISBN 0130669970.
  4. ^ Moss, G. P.; W.H. Powell. "RC-81.1.1. Monovalent radical centers in saturated acyclic and monocyclic hydrocarbons, and the mononuclear EH4 parent hydrides of the carbon family". IUPAC Recommendations 1993. Department of Chemistry, Queen Mary University of London. Archived from the original on 9 February 2015. Retrieved 25 February 2015.
  5. ^ "R-2. 5 Substituent Prefix Names Derived from Parent Hydrides". IUPAC. 1993. section P-56.2.1
  6. ^ "Revised Nomenclature for Radicals, Ions, Radical Ions and Related Species (IUPAC Recommendations 1993: RC-81.3. Multiple radical centers)".

External links

Alcohol

In chemistry, an alcohol is any organic compound in which the hydroxyl functional group (–OH) is bound to a carbon. The term alcohol originally referred to the primary alcohol ethanol (ethyl alcohol), which is used as a drug and is the main alcohol present in alcoholic beverages. An important class of alcohols, of which methanol and ethanol are the simplest members, includes all compounds for which the general formula is CnH2n+1OH. It is these simple monoalcohols that are the subject of this article.

The suffix -ol appears in the IUPAC chemical name of all substances where the hydroxyl group is the functional group with the highest priority. When a higher priority group is present in the compound, the prefix hydroxy- is used in its IUPAC name. The suffix -ol in non-IUPAC names (such as paracetamol or cholesterol) also typically indicates that the substance is an alcohol. However, many substances that contain hydroxyl functional groups (particularly sugars, such as glucose and sucrose) have names which include neither the suffix -ol, nor the prefix hydroxy-.

Alcohol oxidoreductase

Alcohol oxidoreductases are oxidoreductase enzymes that act upon an alcohol functional group.They are classified under "1.1" in the EC number numbering system.

Aldehyde

An aldehyde or alkanal is an organic compound containing a functional group with the structure −CHO, consisting of a carbonyl center (a carbon double-bonded to oxygen) with the carbon atom also bonded to hydrogen and to an R group, which is any generic alkyl or side chain. The group—without R—is the aldehyde group, also known as the formyl group. Aldehydes are common in organic chemistry, and many fragrances are aldehydes.

Alpha and beta carbon

The alpha carbon (Cα) in organic molecules refers to the first carbon atom that attaches to a functional group, such as a carbonyl. The second carbon atom is called the beta carbon (Cβ),[1] and the system continues naming in alphabetical order with Greek letters.

The nomenclature can also be applied to the hydrogen atoms attached to the carbon atoms. A hydrogen atom attached to an alpha carbon atom is called an alpha-hydrogen atom, a hydrogen atom on the beta-carbon atom is a beta hydrogen atom, and so on.

This naming standard may not be in compliance with IUPAC nomenclature, which encourages that carbons be identified by number, not by Greek letter, but it nonetheless remains very popular, in particular because it is useful in identifying the relative location of carbon atoms to other functional groups.

Organic molecules with more than one functional group can be a source of confusion. Generally the functional group responsible for the name or type of the molecule is the 'reference' group for purposes of carbon-atom naming. For example, the molecules nitrostyrene and phenethylamine are very similar; the former can even be reduced into the latter. However, nitrostyrene's α-carbon atom is adjacent to the phenyl group; in phenethylamine this same carbon atom is the β-carbon atom, as phenethylamine (being an amine rather than a styrene) counts its atoms from the opposite "end" of the molecule.

Amide

An amide ( or or ), also known as an acid amide, is a compound with the functional group RnE(O)xNR′2 (R and R′ refer to H or organic groups). Most common are carboxamides (organic amides) (n = 1, E = C, x = 1), but many other important types of amides are known, including phosphoramides (n = 2, E = P, x = 1 and many related formulas) and sulfonamides (E = S, x = 2). The term amide refers both to classes of compounds and to the functional group (RnE(O)xNR′2) within those compounds.

Amide can also refer to the conjugate base of ammonia (the anion H2N−) or of an organic amine (an anion R2N−). For discussion of these "anionic amides", see Alkali metal amides.

Due to the dual use of the word 'amide', there is debate as to how to properly and unambiguously name the derived anions of amides in the first sense (i.e., deprotonated acylated amines), a few of which are commonly used as nonreactive counterions.The remainder of this article is about the carbonyl–nitrogen sense of amide.

Amine

In organic chemistry, amines (, UK also ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group (these may respectively be called alkylamines and arylamines; amines in which both types of substituent are attached to one nitrogen atom may be called alkylarylamines). Important amines include amino acids, biogenic amines, trimethylamine, and aniline; see Category:Amines for a list of amines. Inorganic derivatives of ammonia are also called amines, such as chloramine (NClH2); see Category:Inorganic amines.The substituent -NH2 is called an amino group.Compounds with a nitrogen atom attached to a carbonyl group, thus having the structure R–CO–NR′R″, are called amides and have different chemical properties from amines.

Betaine

A betaine () in chemistry is any neutral chemical compound with a positively charged cationic functional group such as a quaternary ammonium or phosphonium cation (generally: onium ions) that bears no hydrogen atom and with a negatively charged functional group such as a carboxylate group that may not be adjacent to the cationic site. A betaine thus may be a specific type of zwitterion. Historically, the term was reserved for TMG (trimethylglycine) only. Biologically, betaine is involved in methylation reactions and detoxification of homocysteine.

The pronunciation of the compound reflects its origin and first isolation from sugar beets (Beta vulgaris subsp. vulgaris), and does not derive from the Greek letter beta (β), however, it often is pronounced beta-INE or BEE-tayn.In biological systems, many naturally occurring betaines serve as organic osmolytes, substances synthesized or taken up from the environment by cells for protection against osmotic stress, drought, high salinity, or high temperature. Intracellular accumulation of betaines, non-perturbing to enzyme function, protein structure, and membrane integrity, permits water retention in cells, thus protecting from the effects of dehydration. It is also a methyl donor of increasingly recognised significance in biology.

Carboxylic acid

A carboxylic acid is an organic compound that contains a carboxyl group (C(=O)OH). The general formula of a carboxylic acid is R–COOH, with R referring to the rest of the (possibly quite large) molecule. Carboxylic acids occur widely and include the amino acids (which make up proteins) and acetic acid (which is part of vinegar and occurs in metabolism).

Salts and esters of carboxylic acids are called carboxylates. When a carboxyl group is deprotonated, its conjugate base forms a carboxylate anion. Carboxylate ions are resonance-stabilized, and this increased stability makes carboxylic acids more acidic than alcohols, along with the electron-withdrawing effect of the carbonyl bond, which makes the terminal oxygen-hydrogen bond weaker and thus makes acid dissociation more favorable (lowers pKa).

Carboxylic acids can be seen as reduced or alkylated forms of the Lewis acid carbon dioxide; under some circumstances they can be decarboxylated to yield carbon dioxide.

Heptose

A heptose is a monosaccharide with seven carbon atoms.

They have either an aldehyde functional group in position 1 (aldoheptoses) or a ketone functional group in position 2 (ketoheptoses).

Hydroxy group

A hydroxy or hydroxyl group is the entity with the formula OH. It contains oxygen bonded to hydrogen. In organic chemistry, alcohol and carboxylic acids contain hydroxy groups. The anion [OH−], called hydroxide, consists of a hydroxyl group.

According to IUPAC rules, the term hydroxyl refers to the radical OH only, while the functional group −OH is called hydroxy group.

IUPAC nomenclature of organic chemistry

In chemical nomenclature, the IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). It is published in the Nomenclature of Organic Chemistry (informally called the Blue Book). Ideally, every possible organic compound should have a name from which an unambiguous structural formula can be created. There is also an IUPAC nomenclature of inorganic chemistry.

To avoid long and tedious names in normal communication, the official IUPAC naming recommendations are not always followed in practice, except when it is necessary to give an unambiguous and absolute definition to a compound. IUPAC names can sometimes be simpler than older names, as with ethanol, instead of ethyl alcohol. For relatively simple molecules they can be more easily understood than non-systematic names, which must be learnt or looked up. However, the common or trivial name is often substantially shorter and clearer, and so preferred. These non-systematic names are often derived from an original source of the compound. In addition, very long names may be less clear than structural formulae.

Methoxy group

A methoxy group is the functional group consisting of a methyl group bound to oxygen. This alkoxy group has the formula O–CH3. On a benzene ring, the Hammett equation classifies a methoxy substituent as an electron-donating group.

Nitro compound

Nitro compounds are organic compounds that contain one or more nitro functional groups (−NO2). The nitro group is one of the most common explosophores (functional group that makes a compound explosive) used globally. The nitro group is also strongly electron-withdrawing. Because of this property, C−H bonds alpha (adjacent) to the nitro group can be acidic. For similar reasons, the presence of nitro groups in aromatic compounds retards electrophilic aromatic substitution but facilitates nucleophilic aromatic substitution. Nitro groups are rarely found in nature, being almost invariably produced by nitration reactions starting with nitric acid.

Organic redox reaction

Organic reductions or organic oxidations or organic redox reactions are redox reactions that take place with organic compounds. In organic chemistry oxidations and reductions are different from ordinary redox reactions because many reactions carry the name but do not actually involve electron transfer in the electrochemical sense of the word. Instead the relevant criterion for organic oxidation is gain of oxygen and/or loss of hydrogen Simple functional groups can be arranged in order of increasing oxidation state. The oxidation numbers are only an approximation:

When methane is oxidized to carbon dioxide its oxidation number changes from −4 to +4. Classical reductions include alkene reduction to alkanes and classical oxidations include oxidation of alcohols to aldehydes. In oxidations electrons are removed and the electron density of a molecule is reduced. In reductions electron density increases when electrons are added to the molecule. This terminology is always centered on the organic compound. For example, it is usual to refer to the reduction of a ketone by lithium aluminium hydride, but not to the oxidation of lithium aluminium hydride by a ketone. Many oxidations involve removal of hydrogen atoms from the organic molecule, and the reverse, reduction adds hydrogens to an organic molecule.

Many reactions classified as reductions also appear in other classes. For instance conversion of the ketone to an alcohol by lithium aluminium hydride can be considered a reduction but the hydride is also a good nucleophile in nucleophilic substitution. Many redox reactions in organic chemistry have coupling reaction reaction mechanism involving free radical intermediates. True organic redox chemistry can be found in electrochemical organic synthesis or electrosynthesis. Examples of organic reactions that can take place in an electrochemical cell are the Kolbe electrolysis.In disproportionation reactions the reactant is both oxidised and reduced in the same chemical reaction forming two separate compounds.

Asymmetric catalytic reductions and asymmetric catalytic oxidations are important in asymmetric synthesis.

Pentose

A pentose is a monosaccharide with five carbon atoms. Pentoses are organized into two groups: Aldopentoses have an aldehyde functional group at position 1. Ketopentoses have a ketone functional group at position 2 or 3. In the cell, pentoses have a higher metabolic stability than hexoses.

Structural isomer

A structural isomer, or constitutional isomer (per IUPAC), is a type of isomer in which molecules with the same molecular formula have different bonding patterns and atomic organization, as opposed to stereoisomers, in which molecular bonds are always in the same order and only spatial arrangement differs. There are multiple synonyms for structural isomers.

Three categories of structural isomers are skeletal, positional, and functional isomers. Positional isomers are also called regioisomers.

Substitution reaction

Substitution reaction (also known as single displacement reaction or single substitution reaction) is a chemical reaction during which one functional group in a chemical compound is replaced by another functional group. Substitution reactions are of prime importance in organic chemistry. Substitution reactions in organic chemistry are classified either as electrophilic or nucleophilic depending upon the reagent involved. There are other classifications as well that are mentioned below.

Organic substitution reactions are classified in several main organic reaction types depending on whether the reagent that brings about the substitution is considered an electrophile or a nucleophile, whether a reactive intermediate involved in the reaction is a carbocation, a carbanion or a free radical or whether the substrate is aliphatic or aromatic. Detailed understanding of a reaction type helps to predict the product outcome in a reaction. It also is helpful for optimizing a reaction with regard to variables such as temperature and choice of solvent.

A good example of a substitution reaction is halogenation. When chlorine gas (Cl-Cl) is irradiated, some of the molecules are split into two chlorine radicals (Cl.) whose free electrons are strongly nucleophilic. One of them breaks a weak C-H covalent bond and grabs the liberated proton to form the electrically neutral H-Cl. The other radical reforms a covalent bond with the CH3. to form CH3Cl (methyl chloride).

Sulfoxide

A sulfoxide is a chemical compound containing a sulfinyl (SO) functional group attached to two carbon atoms. It is a polar functional group. Sulfoxides are the oxidized derivatives of sulfides. Examples of important sulfoxides are alliin, a precursor to the compound that gives freshly crushed garlic its aroma, and dimethyl sulfoxide (DMSO), a common solvent.

Triazene

Triazene, also known as triazanylene, is an unsaturated inorganic compound having the chemical formula N3H3. It has one double bond, and is the second-simplest member of the azene class of hydronitrogen compounds, and is not found in nature. It is also the name given to the functional group consisting of an amine directly bonding to an azo group, i.e. with the linkage R1R2N-N=NR3 where R1, R2 and R3 are substituents. The functional group is also called a diazoamino group (but only one of the two substituents R1 and R3 may be hydrogen) because it is related to a diazo group.

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.