functional group

[guān néng tuán]

Atoms or atomic clusters that determine the chemical properties of organic compounds

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Functional groups are atoms or Atomic cluster 。 Common functional groups include hydroxyl 、 carboxyl , ether bond Aldehyde group 、 carbonyl Etc. Organic chemical reactions mainly occur on functional groups, which play a decisive role in the properties of organic substances. - X (X is a halogen atom, for halogenated hydrocarbons, the halogen atom can be considered as its functional group^[1] However, some textbooks believe that the carbon halogen bond is its functional group^[4] ）、-OH、-CHO、-COOH、-NO two 、-SO three H、-NH two RCO -, these functional groups determine the Halohydrocarbon , alcohol or phenol aldehyde , carboxylic acid Nitro compound Or the chemical properties of nitrite, sulfonic acid, amine and amide.

Chinese name: functional group

Foreign name: functional group
Alias: Characteristic groups^[5]

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Resulting heterogeneity

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Organic substances are classified according to composition, carbon chain, functional group and homologue Etc.

The isomeric types of organic matter are Carbon chain isomerism , functional groups Heterogeneous location And the types of functional groups. For organic compounds of the same kind Isomerism It is the position isomerism of functional groups.

For the same atomic composition, different functional groups are formed, thus forming different types of organic matter, which is the isomerism of functional groups. For example, aldehydes and ketones with the same number of carbon atoms, carboxylic acids with the same number of carbon atoms and ester , which are caused by the formation of different functional groups.^[1]

chemical property

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Functional groups play a decisive role in the properties of organic matter, - X, - OH, - CHO, - COOH, - NO two 、-SO three H、-NH two RCO -, these functional groups determine the Halohydrocarbon 、 alcohol or phenol 、 aldehyde 、 carboxylic acid 、 Nitro compound or Nitrite 、 Sulfonic acid organics 、 amine Class amide Chemical properties of the class. Therefore, learning the nature of organic matter is actually learning the nature of functional groups. The organic matter containing any functional group should have the chemical nature of this functional group, and the organic matter without this functional group does not have the chemical nature of this functional group, which is a special point to be recognized in learning organic chemistry. For example, aldehydes can Silver mirror reaction , or newly made Copper hydroxide Suspension The oxidation can be considered as a characteristic reaction of aldehydes; However, this is not unique to aldehydes, but to aldehyde groups. Therefore, all substances containing aldehyde groups, such as glucose, formic acid and formate, can undergo silver mirror reaction or be oxidized by newly prepared copper hydroxide suspension.^[2-3]

Other properties

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In organic molecules Group There is interaction between them, including functional groups Alkyl group The influence of hydrocarbon groups on functional groups, and the interaction between functional groups in materials containing multifunctional groups.

① Alcohol phenol There are hydroxyl groups in the molecules of and carboxylic acids, so both can react with sodium to release hydrogen. However, due to the different groups connected, there are differences in acidity.

R-OH is neutral and cannot be mixed with NaOH and Na two CO three Reaction; The hydroxyl group directly connected with the benzene ring becomes the phenolic hydroxyl group, which does not benzene ring The directly linked hydroxyl group becomes the alcohol hydroxyl group.

C six H five -OH is extremely weak acid, weaker than carbonic acid, but stronger than HCO three -（ Bicarbonate ）Be strong. Cannot make indicator Discoloration, can react with NaOH. Phenol can also sodium carbonate Reaction Sodium phenolate And sodium bicarbonate ；

R-COOH is weakly acidic, with the common property of acid, and can be mixed with NaOH and Na two CO three Reaction.

Obviously, in the carboxylic acid, the influence of the carbonyl group in the carboxyl group makes the hydrogen in the hydroxyl group easy to ionize.

② Both aldehydes and ketones have carbonyl groups (>C=O), but in aldehydes Carbonyl carbon The atom is connected to a hydrogen atom, and ketone The carbon atom of medium carbonyl group is connected with hydrocarbon group, so the former has reducibility, while the latter is relatively stable and is not oxidized by weak oxidant.

③ The atomic groups in the same molecule also affect each other. For example, phenol and - OH make benzene ring easy to replace (activate), phenyl Make - OH appear acidic (i.e ionization Exit H + )。 fructose Medium, polyhydroxy affects carbonyl, which may occur Silver mirror reaction 。

It can be seen from the above that we can not only determine the chemical property The functional groups contained in a substance can also be judged by its chemical properties. If glucose can undergo silver mirror reaction and be hydrogenated and reduced to six component alcohol, it can be known that it has aldehyde group; It can be esterified with acid glucose pentaacetate , indicating that it has five hydroxyl groups, so it is a polyhydroxy aldehyde.

Organic chemical reactions mainly occur on functional groups. Therefore, it is necessary to pay attention to the bond where the reaction occurs so as to write correctly Chemical equation 。

For example, the hydrogenation of aldehyde occurs on the aldehyde carbon oxygen bond, and the oxidation occurs on the Aldehyde group On the hydrocarbon bond of; The substitution of halogenated hydrocarbon occurs on the carbon halogen bond, and the elimination occurs on the carbon halogen bond and the hydrocarbon bond of adjacent carbon atoms; The esterification of alcohols is the breaking of the O-H bond in the hydroxyl group, and the substitution is the breaking of the C-O bond; Addition polymerization is a unique reaction of compounds containing carbon carbon double bonds (>C=C<) (not necessarily olefins). During polymerization, the groups on the carbon double bonds are thrown up and down, and the one bond in the double bonds is opened and connected hand in hand.^[1]

type

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Alkyl group

Hydrocarbon base composition, chemical formula

According to contained pi bond Different Alkyl group Functional groups have different properties. be careful : Alkyl group (such as methyl methylene ）It is not a functional group, but phenyl is a functional group.

classification	Name of functional group	chemical formula	English prefix	English suffix
alkane	alkyl	RH	alkyl-	-ane
olefin	Alkenyl	R two C=CR two	alkenyl-	-ene
Alkyne	Alkynyl group	RC≡CR'	alkynyl-	-yne
benzene And derivatives	phenyl	RC six H five RPh	phenyl-	-benzene
toluene And derivatives	benzyl	RCH two C six H five RBn	benzyl-	1-( substituent )toluene

Containing halogen substituent

Halogenated hydrocarbon contains carbon- halogen Bond, bond energy varies with halogen. General division Fluorohydrocarbon In addition, halogenated hydrocarbon can occur Nucleophilic substitution reaction and Extinction reaction 。

classification	Name of functional group	chemical formula	English prefix	English suffix
Haloalkane	Carbohalide bond	RX	halo-	alkyl halide
Fluoroalkane	Fluorocarbon bond	RF	fluoro-	alkyl fluoride
chloroalkane	Carbon chlorine bond	RCl	chloro-	alkyl chloride
Bromoalkane	Carbon bromine bond	RBr	bromo-	alkyl bromide
Iodoalkane	Carbon iodine bond	RI	iodo-	alkyl iodide

Oxygen content

Different carbon oxygen bonds will Hybridization There are differences in nature due to different degrees. The sp hybrid oxygen atoms are Electron absorption effect , while sp has Electron donor effect 。

classification	Name of functional group	chemical formula	English prefix	English suffix
Acyl halide	Haloformyl	RCOX	haloformyl-	-oyl halide
alcohol	hydroxyl	ROH	hydroxy-	-ol
ketone	carbonyl	RCOR'	keto-, oxo-	-one
aldehyde	Aldehyde group	RCHO	aldo-	-al
Carbonate	Carbonate	ROCOOR		alkyl carbonate
Carboxylate	Carboxylate	RCOO	carboxy-	-oate
carboxylic acid	carboxyl	RCOOH	carboxy-	-oic acid
ether	ether	ROR'	alkoxy-	alkyl alkyl ether
ester	ester	RCOOR'		alkyl alkan oate
Hydroperoxide	Hydrogen peroxide	ROOH	hydroperoxy-	alkyl hydroperoxide
peroxide	Peroxy group	ROOR	peroxy-	alkyl peroxide

Nitrogenous

classification	Name of functional group	chemical formula	English prefix	English suffix
amide	amide	RCONH two	carboxamido-	-amide
amine	Primary amine	RNH two	amino-	-amine
	Secondary amine	R two NH	amino-	-amine
	Tertiary amine	R three N	amino-	-amine
	quaternary ammonium salt Quaternary ammonium cation	R four N	ammonio-	-ammonium
Imine	Primary ketoimine	RC(=NH)R'	imino-	-imine
	Secondary ketoimine	RC(=NR )R'	imino-	-imine
	Primary aldimine	RC(=NH)H	imino-	-imine
	Secondary aldimine	RC(=NR')H	imino-	-imine
Imide	Imide	RC(=O)NC(=O)R'	imido-	-imide
Azide	Azide	RN three	azido-	alkyl azide	Azide benzene
Azo compound	Azo group	RN two R'	azo-	-diazene	Methyl yellow
Cyanate ester	Cyanate ester	ROCN	cyanato-	alkyl cyanate
Cyanate ester	Isonitrile	RNC	isocyano-	alkyl isocyanide
Isocyanate	Isocyanate	RNCO	isocyanato-	alkyl isocyanate	Methyl isocyanate
Isocyanate	Isothiocyanate	RNCS	isothiocyanato-	alkyl isothiocyanate	Allyl isothiocyanate
Nitrate ester	Nitrate ester	RONO two	nitrooxy-, nitroxy-	alkyl nitrate	N-amyl nitrate
nitrile	Cyano group	RCN	cyano-	alkane nitrile alkyl cyanide	Benzonitrile
Nitrite	Nitrite	RONO	nitrosooxy-	alkyl nitrite	Isoamyl nitrite
Nitro compound	Nitro	RNO two	nitro-		Nitromethane
Nitroso compound	nitroso group	RNO	nitroso-		Nitroso benzene
pyridine And derivatives	Pyridyl	RC five H four N	4-pyridyl (pyridin-4-yl) 3-pyridyl (pyridin-3-yl) 2-pyridyl (pyridin-2-yl)	-pyridine	nicotine

Phosphorous sulfur

Compared with nitrogen and oxygen of the same group, Organophosphorus compound and Organic sulfur compounds The heteroatoms in tend to form more bonds.

classification	Name of functional group	chemical formula	English prefix	English suffix
phosphine	phosphine	R three P	phosphino-	-phosphane
Phosphodiester	phosphate	HOPO(OR) two	phosphoric acid di( substituent ) ester	di( substituent ) hydrogenphosphate
Phosphite ester	Phosphite ester	RP(=O)(OH) two	phosphono-	substituent phosphonic acid
phosphate	phosphate	ROP(=O)(OH) two	phospho-
Thioether	Thioether	RSR'		di( substituent ) sulfide
Sulfone	Sulfonyl group	RSO two R'	sulfonyl-	di( substituent ) sulfone
sulfonic acid	Sulfonic group	RSO three H	sulfo-	substituent sulfonic acid
Sulfoxide	Sulphonyl group	RSOR'	sulfinyl-	di( substituent ) sulfoxide
mercaptan	Mercapto group	RSH	mercapto-, sulfanyl-	-thiol
Thiocyanate	Thiocyanate	RSCN	thiocyanato-	alkyl thiocyanate
Disulfide	Disulfide bond	RSSR'		alkyl alkyl disulfide

Determination of main group

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If the named compound contains multiple characteristic groups (except those that cannot be used as suffixes), only one characteristic group can be selected as the suffix, and this group is called the main group.^[5]

High order (priority) of characteristic group type (in descending order)
sequence	Type of compound by characteristic group	general classes of compounds by characteristic group
one	Free radical	radicals
two	anion	anions
three	Positive ion	cations
four	Zwitterionic compound	zwitterionic compounds
five	Carboxylic acid (COOH, C (O) O) two H， Then they are their S and Se derivatives, which are sulfonic acid, sulphite, selenic acid, phosphonic acid, arsonic acid, etc.)	acids (in the order of COOH, C(O)O two H, then their S and Se derivatives followed by sulfonic, sulfinic, selenonic acid, etc., and phosphonic, arsenic acid,etc.)
six	Acid anhydride	anhydrides
seven	ester	esters
eight	Acyl halide	acid halides
nine	amide	amides
ten	Hydrazide	hydrazides
eleven	Diimide	imides
twelve	nitrile	nitriles
thirteen	Aldehydes, followed by thioaldehydes, selenium aldehydes and telluride aldehydes	aldehydes followed by thioaldehydes, selenoaldehydes, and telluroaldehydes
fourteen	Ketone, followed by thioketone, selenoketone and tellurione	ketones followed by thioketones, selenoketones, and telluroketones
fifteen	Alcohol and phenol, followed by mercaptan, selenol and telluriol	alcohols and phenols followed by thiols, selenols, and tellurols
sixteen	Hydroperoxide, followed by thiohydroperoxide, selenium hydroperoxide and tellurium hydroperoxide	hydroperoxides followed by thiohydroperoxides, selenohydroperoxides, and tellurohydroperoxides
seventeen	amine	amines
eighteen	Imine	imines
nineteen	Hydrazine (hydrazine), phosphane (diphosphate), etc	hydrazines, phosphanes, etc.
twenty	Ether, followed by sulfide, selenide and tellurium ether	ethers followed by sulfides, selenides, and tellurides
twenty-one	Peroxide, followed by persulfide, selenide and telluride	peroxides followed by disulfides, diselenides, and ditellurides^[5]

Modification group of functional group

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Some derivatives of main characteristic groups or functional parent compounds can be named by adding the name of this modified group after their original name.^[5]

Example:

CH three —CH two - CHO propanal

→　CH three —CH two —CH(OCH three ) two Propanal dimethyl acetal;

→　CH three —CH two - CH=NOH propional oxime;

→　CH three —CH two —CH=NNH two Propanal hydrazone.

CH three —CH two - COOH propionic acid

→　CH three —CH two —COO=CH three Propionic acid methyl ester [Note] ；

→　CH three —CH two —CO—NH—NH two Propionic acid hydrazide.

[Note] The more systematic name "methyl propionate" can also be used in English, but this is the only way to name carboxylates in Chinese, which is also called "methyl propionate" at this time.^[5]

Functional group replacement

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After the oxygen atom or hydroxyl group in the structure is replaced by other atoms or groups, certain prefixes or affixes can be inserted into the names or common names of original characteristic groups, functional parent compounds to name them. For example, the characteristic groups "- thiosulfonic acid" and "- thiocarboxylic acid" after the replacement of oxygen by sulfur. Similarly, after the oxygen atom is replaced with - O-O-group, the prefix "peroxide" or "peroxide" can be added when naming, such as peroxycarboxylic acid. When oxygen atom or hydroxyl group is replaced by sulfur element or sulfur element group, use the hyphen "replace"; when other atoms or groups are replaced, use the hyphen "replace" to name.^[5]

Example:

CH three - COOH acetic acid

→　CH three - CO - SH Ethyl thio- S -Acid, Thioethyl- S -Thioacetic S -acid）；

→　CH three - CS - OH Ethyl thio- O -Acid, Thioethyl- O -Thioacetic O -acid）。

CH three —CH two —CH two —CH two - COOH valeric acid

→　CH three —CH two —CH two —CH two - CO - SH pentathio- S -Acids, Thiopene- S -Acid;

→　CH three —CH two —CH two —CH two - C (=NH) - OH amino subunit, pentamidic acid.^[5]

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