The Special Feature That Determines the Family Name and Chemical Reactivity of an Organic Compound

Functional Groups

Functional groups refer to specific atoms bonded in a sure organisation that give a chemical compound certain physical and chemical properties.

Learning Objectives

Define the term "functional group" as it applies to organic molecules

Key Takeaways

Key Points

• Functional groups are often used to "functionalize" a compound, affording it dissimilar concrete and chemical properties than information technology would have in its original form.
• Functional groups volition undergo the aforementioned blazon of reactions regardless of the chemical compound of which they are a part; however, the presence of certain functional groups within close proximity tin can limit reactivity.
• Functional groups can be used to distinguish similar compounds from each other.

Central Terms

• functional group: A specific grouping of elements that is feature of a course of compounds, and determines some properties and reactions of that course.
• functionalization: Addition of specific functional groups to afford the compound new, desirable properties.

The Office of Functional Groups

In organic chemistry, a functional group is a specific group of atoms or bonds within a chemical compound that is responsible for the characteristic chemical reactions of that compound. The same functional group will behave in a similar mode, by undergoing similar reactions, regardless of the compound of which it is a part. Functional groups too play an of import office in organic compound nomenclature; combining the names of the functional groups with the names of the parent alkanes provides a way to distinguish compounds.

The atoms of a functional group are linked together and to the residuum of the compound by covalent bonds. The commencement carbon atom that attaches to the functional group is referred to as the alpha carbon; the 2d, the beta carbon; the third, the gamma carbon, etc. Similarly, a functional group can be referred to as principal, secondary, or tertiary, depending on if it is attached to one, two, or three carbon atoms.

Classification of alcohols: Alcohols are a common functional group (-OH). They tin can exist classified every bit primary, secondary, or tertiary, depending on how many carbon atoms the central carbon is attached to.

Functional Groups and Reactivity

Functional groups play a significant office in directing and controlling organic reactions. Alkyl chains are frequently nonreactive, and the direction of site-specific reactions is difficult; unsaturated alkyl chains with the presence of functional groups allow for college reactivity and specificity. Often, compounds are functionalized with specific groups for a specific chemic reaction. Functionalization refers to the add-on of functional groups to a compound by chemical synthesis. Through routine synthesis methods, any kind of organic compound tin exist attached to the surface. In materials science, functionalization is employed to accomplish desired surface properties; functional groups can besides be used to covalently link functional molecules to the surfaces of chemic devices.

In organic chemistry, the most common functional groups are carbonyls (C=O), alcohols (-OH), carboxylic acids (CO_twoH), esters (CO₂R), and amines (NH_ii). It is of import to exist able to recognize the functional groups and the physical and chemical backdrop that they afford compounds.

Organic chemistry functional groups lesson: This video provides a great overview of the various functional groups in organic chemistry.

Alcohols

Alcohols are functional groups characterized by the presence of an -OH group.

Learning Objectives

Identify the general backdrop of the alcohol functional grouping

Key Takeaways

Key Points

• Due to the presence of an -OH group, alcohols tin hydrogen bond. This leads to higher boiling points compared to their parent alkanes.
• Alcohols are polar in nature. This is attributed to the difference in electronegativity between the carbon and the oxygen atoms.
• In chemical reactions, alcohols ofttimes cannot get out the molecule on their own; to leave, they often become protonated to water, which is a better leaving grouping. Alcohols also can become deprotonated in the presence of a stiff base.

Cardinal Terms

• alkane: Any of the saturated hydrocarbons—including marsh gas, ethane, and compounds with long carbon chain known as paraffins, etc.— that take a chemical formula of the class CnH2n+2.
• aldehyde: Whatsoever of a large class of reactive organic compounds (R·CHO) having a carbonyl functional group fastened to ane hydrocarbon radical and a hydrogen atom.
• carboxylic acid: Whatever of a form of organic compounds containing a carboxyl functional group—a carbon with a double bond to an oxygen and a single bond to another oxygen, which is in turn bonded to a hydrogen.
• leaving grouping: In organic chemical science, the species that leaves the parent molecule following a substitution reaction.

Alcohols are organic compounds in which the hydroxyl functional grouping (-OH) is bound to a carbon atom. Alcohols are an important class of molecules with many scientific, medical, and industrial uses.

Classification of Alcohols

According to the IUPAC nomenclature system, an booze is named by dropping the final "-e" of the parent carbon chain (paraffin, alkene, or alkyne in near cases) and the addition of "-ol" as the ending. If the location of the hydroxyl group must be specified, a number is inserted between the parent alkane name and the "-ol" (propan-ane-ol) or before the IUPAC name (1-propanol). If a college priority grouping is present, such as an aldehyde, ketone or carboxylic acrid, then information technology is necessary to apply the prefix "hydroxy-" instead of the ending "-ol."

Alcohols are classified every bit chief, secondary, or third, based upon the number of carbon atoms connected to the carbon atom that bears the hydroxyl group.

The alcohol functional group: Alcohols are characterized by the presence of an -OH group, which is generally in a bent shape, like that of h2o.

Structure and Concrete Backdrop of Alcohols

The structure of an alcohol is like to that of water, as it has a bent shape. This geometrical arrangement reflects the issue of electron repulsion and the increasing steric bulk of the substituents on the primal oxygen atom. Similar h2o, alcohols are polar, containing an unsymmetrical distribution of charge between the oxygen and hydrogen atoms. The high electronegativity of the oxygen compared to carbon leads to the shortening and strengthening of the -OH bail. The presence of the -OH groups allows for hydrogen bonding with other -OH groups, hydrogen atoms, and other molecules. Since alcohols are able to hydrogen bail, their humid points are higher than those of their parent molecules.

Alcohols are able to participate in many chemical reactions. They oftentimes undergo deprotonation in the presence of a strong base. This weak acid behavior results in the formation in an alkoxide salt and a water molecule. Hydroxyl groups alone are not considered proficient leaving groups. Oft, their participation in nucleophilic substitution reactions is instigated past the protonation of the oxygen atom, leading to the formation a h2o moiety—a improve leaving group. Alcohols can react with carboxylic acids to class an ester, and they tin can be oxidized to aldehydes or carboxylic acids.

Alcohols have many uses in our everyday globe. They are constitute in beverages, antifreeze, antiseptics, and fuels. They tin be used as preservatives for specimens in science, and they can exist used in industry as reagents and solvents considering they display an ability to dissolve both polar and non-polar substances.

Ethers

Ethers are a course of organic compounds characterized by an oxygen cantlet connected to 2 alkyl or aryl groups.

Learning Objectives

Define the term "ether" as information technology relates to organic compounds

Key Takeaways

Key Points

• Ethers accept relatively low boiling points due to their inability to course hydrogen bonds with each other.
• Due to the electronegativity difference between the oxygen and carbon atoms of an ether, the molecule is slightly polar.
• Although they have low reactivity overall, the ii lone pairs of electrons on the oxygen cantlet practice afford the ether molecule some reactivity; the ether molecule is subject to reacting with strong acids and serves equally a Lewis base.

Key Terms

• alkene: An unsaturated, aliphatic hydrocarbon with one or more than carbon–carbon double bail.
• ester: A compound nigh often formed by the condensation of an booze and an acid, with emptying of h2o. It contains the functional group C=O joined via carbon to another oxygen cantlet.
• ether: Compound containing an oxygen atom bonded to two hydrocarbon groups.
• amide: Any derivative of an oxoacid in which the hydroxyl grouping has been replaced with an amino or substituted amino group; particularly such derivatives of a carboxylic acid, the carboxamides.

Structure of Ethers

Ethers are a class of organic compounds that contain an ether group. An ether grouping is an oxygen atom connected to two alkyl or aryl groups. They follow the full general formula R-O-R'. The C-O-C linkage is characterized by bond angles of 104.five degrees, with the C-O distances being about 140 pm. The oxygen of the ether is more electronegative than the carbons. Thus, the alpha hydrogens are more acidic than in regular hydrocarbon chains.

Ethers: The general structure of an ether. An ether is characterized past an oxygen bonded to two alkyl or aryl groups, represented here by R and R'. The substituents can exist, but do not need to be, the same.

Nomenclature of Ethers

There are two means to name ethers. The most common style is to place the alkyl groups on either side of the oxygen atom in alphabetical order, then write "ether." For example, ethyl methyl ether is the ether that has an ethyl group and a methyl group on either side of the oxygen atom. If the two alkyl groups are identical, the ether is chosen di[alkyl] ether. For example, diethyl ether is the ether with an ethyl group on each side of the oxygen cantlet.

The other style of naming ethers is the formal, IUPAC method. This way, the form is: [short alkyl chain][oxy][long alkyl chain]. For example, the IUPAC proper name for ethyl methyl ether would exist methoxyethane.

In cyclic ethers, the stem of the compound is known equally a oxacycloalkane. The "oxa" is an indicator of the replacement of the carbon by an oxygen in the ring. An example is oxacyclopentane, a five-membered ring in which in that location are four carbon atoms and ane oxygen cantlet.

Tetrahydrofuran (THF): The common name of the circadian ether "oxacyclopentane" is tetrahydrofuran, or THF. Information technology is a common organic solvent that is miscible with water.

Backdrop of Ethers

Ethers are rather nonpolar due to the presence of an alkyl group on either side of the key oxygen. The presence of the bulky alkyl groups that are next to it means that the oxygen atom is largely unable to participate in hydrogen bonding. Ethers, therefore, have lower boiling points compared to alcohols of similar molecular weight. Even so, every bit the alkyl chain of the ethers becomes longer, the divergence in boiling points becomes smaller. This is due to the effect of increased Van der Waals interactions as the number of carbons increases, and therefore the number of electrons increases as well. The two lone pairs of electrons present on the oxygen atoms arrive possible for ethers to form hydrogen bonds with h2o. Ethers are more polar than alkenes, but not as polar as esters, alcohols or amides of comparable structures.

Reactions

Ethers have relatively depression chemic reactivity, only they are still more reactive than alkanes. Although they resist undergoing hydrolysis, they are often cleaved by acids, which results in the formation of an alkyl halide and an booze. Ethers tend to form peroxides in the presence of oxygen or air. The general formula is R-O-O-R'. Ethers can serve as Lewis and Bronsted bases, serving to donate electrons in reactions, or accept protons. Ethers can be formed in the laboratory through the dehydration of alcohols (2R-OH → R-O-R + H_iiO at high temperature), nucleophilic displacement of alkyl halides by alkoxides (R-ONa + R'-X → R-O-R' + NaX), or electrophilic addition of alcohols to alkenes (R₂C=CR₂ + R-OH → R₂CH-C(-O-R)-R₂)_.

Aldehydes and Ketones

Aldehydes and ketones are classes of organic compounds that contain a carbonyl (C=O) group.

Learning Objectives

Identify the general backdrop of ketones and aldehydes

Key Takeaways

Key Points

• The carbonyl functional group is a carbon double bonded to an oxygen. Depending on the location of the carbonyl group, it is termed differently; ketones contain the carbonyl inside the chemical compound and aldehydes contain the carbonyl at the end of the organic chemical compound.
• Ketones and aldehydes can undergo keto- enol tautomerism. This refers to the equilibrium between the two possible tautomers. The interconversion of the two forms involves the motility of a proton and the shifting of bonding electrons. This equilibrium affords the compounds more reactivity.
• Ketones and aldehydes participate in a variety of reactions. They tin undergo oxidation reactions, in which they go oxidized to the corresponding carboxylic acids.

Key Terms

• tautomerism: A form of isomerism in which a dynamic equilibrium betwixt multiple isomers exists, such as that between an enol and a ketone.
• oxidize: To increase the valence (the positive charge) of an chemical element past removing electrons.
• aldehyde: An organic compound containing a formyl group, which is a functional grouping with the structure R-CHO.
• sp2: Hybrid orbital that forms when one pi bond is required for the double bond, and just three σ bonds are formed per carbon atom. The 2s orbital is mixed with only two of the three 2p orbitals.
• ketone: A chemical compound containing an oxygen atom joined to a carbon cantlet by a double bail.

In organic chemistry, a carbonyl group is a functional group which has a carbon double bonded to an oxygen atom: C=O.

Keto-enol tautomers: There exists an equilibrium between the ketone and the enol forms, which involves a shifting of the double bond and the movement of a proton.

Ketones

When a carbonyl functional group is placed within a molecule, it is known as a ketone. Ketones are organic compounds with the structure RC(=O)R', where R and R' can be a variety of carbon-containing substituents. IUPAC nomenclature rules dictate that ketone molecules are named past changing the suffix of the parent carbon molecule to "-one." If the position of the ketone must exist specified, and so a number is placed between the parent chain name and the "-one" prefix (east.thou., propan-2-one), or at the beginning of the IUPAC name. The prefixes "oxo-" and "keto-" are used to describe the ketone functional grouping.

Ketone: A ketone is a blazon of organic chemical compound where a carbonyl group bonds to two other carbon atoms of the carbon backbone.

The ketone carbon is sp^two hybridized, and it adopts a trigonal planar geometry effectually the ketonic carbon. Equally such, the C–C–O and C–C–C bond angles are approximately 120 degrees. Due to the carbonyl group, ketones are polar and are able to collaborate with other compounds through hydrogen bonding; this hydrogen bail adequacy makes ketones more soluble in water than related methylene compounds. Ketones are not usually hydrogen bail donors, and they tend not to exhibit intermolecular attractions with other ketones. As a result, ketones are often more volatile than alcohols and carboxylic acids of comparable molecular weights. Ketones have blastoff -hydrogens which participate in keto-enol tautomerism. In the presence of a strong base, enolate germination and subsequent deprotonation of the enolate volition occur.

Aldehydes

Aldehyde: An aldehyde is characterized by the presence of a carbonyl functional grouping at the cease of a compound'south carbon skeleton.

An aldehyde is an organic chemical compound that contains a carbonyl group with the central carbon bonded to a hydrogen and R group (R-CHO). Aldehydes differ from ketones in that the carbonyl is placed at the end of the carbon skeleton rather than betwixt two carbon atoms of the courage. Like ketones, aldehydes are sp² hybridized and tin exist in the keto or enol tautomer. Aldehydes are named by dropping the suffix of the parent molecule, and adding the suffix "-al." For example, a three-carbon chain with an aldehyde group on a last carbon would be propanal. If there are higher guild functional groups on the chemical compound, the prefix "oxo-" tin be used to point which carbon atom is part of the aldehyde grouping. If the location of the aldehyde must be specified, a number can be used in between the parent chain and suffix, or at the beginning of the compound name.

Similarities of Aldehydes and Ketones

Both aldehydes and ketones exist in an equilibrium with their enol forms; the enol form is defined as an alkene with a hydroxyl group affixed to one of the carbon atoms composing the double bond. The keto form predominates at equilibrium for most ketones. Withal, the enol class is important for some reactions because the deprotonated enolate form is a strong nucleophile. The equilibrium is strongly thermodynamically driven, and at room temperature the keto form is favored. The interconversion can exist catalyzed by the presence of either an acid or a base.

Keto-enol tautomerism: The interconversion betwixt the two forms tin exist catalyzed by an acid or a base of operations.

Ketone and Aldehyde Spectroscopy

Both ketones and aldehydes tin can be identified by spectroscopic methods. They brandish strong CO absorption bands near 1700 cm^-1. In NMR spectroscopy, the carbonyl hydrogen shows a potent absorption peak, and any coupling to protons on the blastoff carbon will also prove potent signals.

Ketones and aldehydes tin both be readily reduced to alcohols, usually in the presence of a strong reducing agent such as sodium borohydride. In the presence of strong oxidizing agents, they can be oxidized to carboxylic acids. As electrophiles, they are bailiwick to assail past nucleophiles, pregnant they participate in many nucleophilic addition reactions.

Carboxylic Acids

Carboxylic acids are organic acids that comprise a carbon atom that participates in both a hydroxyl and a carbonyl functional grouping.

Learning Objectives

Recognize the general properties of carboxylic acids

Key Takeaways

Key Points

• Carboxylic acids are used as precursors to form other compounds such every bit esters, aldehydes, and ketones.
• Carboxylic acids can exhibit hydrogen bonding with themselves, especially in non- polar solvents; this leads to increased stabilization of the compounds and elevates their humid points.
• Since they incorporate both hydroxyl and carbonyl functional groups, carboxylic acids participate in hydrogen bonding every bit both hydrogen acceptors and hydrogen donors.

Key Terms

• nitrile: Any of a form of organic compounds containing a cyano functional group (-C≡Northward).
• olefin: Whatsoever of a class of unsaturated, open-chain hydrocarbons such as ethylene; an alkene with only i carbon-carbon double bail.
• ester: A chemical compound most often formed past the condensation of an booze and an acid, with elimination of water. It contains the functional grouping C=O joined via carbon to another oxygen atom.

A carboxyl group (COOH) is a functional group consisting of a carbonyl group (C=O) with a hydroxyl group (O-H) fastened to the same carbon atom. Carboxyl groups have the formula -C(=O)OH, usually written as -COOH or CO_iiH. Carboxylic acids are a class of molecules which are characterized by the presence of one carboxyl grouping. As proton donors, carboxylic acids are characterized as Brønsted-Lowry acids. Acids with two or more carboxylic groups are called dicarboxylic, tricarboxylic, etc. Salts and esters of carboxylic acids are called carboxylates. Carboxylate ions are resonance-stabilized. This increased stability leads to increased acidity compared to that of alcohols. Generally, in IUPAC nomenclature, carboxylic acids have an "-oic acrid " suffix, although "-ic acid" is the suffix near commonly used.

A carboxylic acid: Carboxylic acids are organic oxoacids characterized by the presence of at least one carboxyl group, which has the formula -C(=O)OH, usually written as -COOH or -CO2H.

Physical Backdrop of Carboxylic Acids

Carboxylic acids deed every bit both hydrogen bond acceptors, due to the carbonyl grouping, and hydrogen bail donors, due to the hydroxyl grouping. As a result, they often participate in hydrogen bonding. Carboxylic acids usually be as dimeric pairs in nonpolar media because of their tendency to "self-associate." This tendency to hydrogen bond gives them increased stability also as college boiling points relative to the acrid in aqueous solution. Carboxylic acids are polar molecules; they tend to be soluble in water, but as the alkyl chain gets longer, their solubility decreases due to the increasing hydrophobic nature of the carbon chain. Carboxylic acids are characterized equally weak acids, meaning that they do non fully dissociate to produce H⁺ cations in a neutral aqueous solution.

Hydrogen bonding between carboxylic acids: Carboxylic acids hydrogen bond with themselves, giving them an increased level of stability.

Spectroscopy of Carboxylic Acids

Carboxylic acids tin be characterized by IR spectroscopy; they exhibit a abrupt band associated with vibration of the C-O bail between 1680 and 1725 cm^-ane. Additionally, a broad top appears in the 2500 to 3000 cm^-1 region. Past ¹H NMR spectroscopy, the hydroxyl hydrogen appears in the 10–13 ppm region, although it is often either broadened or not observed attributable to substitution with traces of h2o.

Applications and Reactivity of Carboxylic Acids

Carboxylic acids are used in the product of polymers, pharmaceuticals, solvents, and food additives. As such, they are often produced industrially on a large scale. Carboxylic acids are by and large produced from oxidation of aldehydes and hydrocarbons, and base of operations catalyzed dehydrogenation of alcohols. They tin can be produced in the laboratory for pocket-sized scale reactions via the oxidation of primary alcohols or aldehydes, oxidative cleavage of olefins, and through the hydrolysis of nitriles, esters, or amides.

Carboxylic acids are widely used as precursors to produce other compounds. Upon exposure to a base, the carboxylic acid is deprotonated and forms a carboxylate salt. They also react with alcohols to produce esters and can undergo reduction reactions past hydrogenation or the apply of reducing agents. There are also various specialized reactions that carboxylic acids participate in that pb to the germination of amines, aldehydes, and ketones.

Esters

Esters are functional groups produced from the condensation of an booze with a carboxylic acid, and are named based on these components.

Learning Objectives

Place the general properties of the ester functional group

Key Takeaways

Fundamental Points

• Esters are a functional group commonly encountered in organic chemistry. They are characterized by a carbon bound to three other atoms: a single bond to a carbon, a double bail to an oxygen, and a single bail to an oxygen. The singly leap oxygen is bound to another carbon.
• Ester names are derived from the parent alcohol and the parent acrid. While unproblematic esters are often called by their common names, all esters tin can be named using the systematic IUPAC proper name, based on the name for the acid followed by the suffix "-oate."
• Esters react with nucleophiles at the carbonyl carbon. The carbonyl is weakly electrophilic, but is attacked by stiff nucleophiles. The C-H bonds adjacent to the carbonyl are weakly acidic, but undergo deprotonation with stiff bases.

Key Terms

• carboxylic acid: Any of a class of organic compounds containing a carboxyl functional group—a carbon with one double bail to an oxygen and a single bond to another oxygen, which is in turn bonded to a hydrogen.
• booze: Form of organic compounds containing a hydroxyl functional grouping.
• nucleophile: A chemical compound or functional grouping that is attractive to centers of positive charge and donates electrons; donates an electron pair to an electrophile to form a bond.

Esters are an important functional group in organic chemical science, and they are more often than not written RCOOR' or RCO_twoR'.

Esters: An ester is characterized by the orientation and bonding of the atoms shown, where R and R' are both carbon-initiated chains of varying length, besides known as alkyl groups.

As usual, R and R' are both alkyl groups or groups initiating with carbon. Esters are derivative of carboxylic acids where the hydroxyl (OH) group has been replaced past an alkoxy (O-R) grouping. They are commonly synthesized from the condensation of a carboxylic acid with an alcohol:

[latex]\text{RCO}_2\text{H} +\text{R}'\text{OH} \rightarrow \text{RCO}_2\text{R}' + \text{H}_2\text{O}[/latex]

Esters are ubiquitous. Most naturally occurring fats and oils are the fatty acid esters of glycerol. Esters are typically fragrant, and those with low enough molecular weights to be volatile are normally used as perfumes and are establish in essential oils and pheromones. Polymerized esters, or polyesters, are important plastics, with monomers linked by esteric units like this:

CO₂RCO₂RCO₂R… etc.

Nomenclature

The word "ester" was coined in 1848 past German chemist Leopold Gmelin, probably every bit a contraction of the German Essigäther, meaning acetic ether.

Ester names are derived from the parent alcohol and acid. For instance, the ester formed by ethanol and ethanoic acid is known as ethyl ethanoate; "ethanol" is reduced to "ethyl," while "ethanoic acid" is reduced to "ethanoate." Other examples of ester names include methyl propanoate, from methanol and propanoic acrid, and butyl octanoate, from butane and octanoic acid.

Ethyl ethanoate: The name ethyl ethanoate is derived from the components from which it is synthesized: ethanol and ethanoic acrid. In this diagram, the carmine office of the molecule represents the portion formerly attributed to ethanol (minus a H), and the greenish role of the molecule represents the ethanoic acid portion (minus an OH). Esterification is a form of dehydration synthesis, so the H and OH components are removed as water.

In the case of esters formed from common carboxylic acids, more colloquial terms are sometimes used. For example, ethanoic acid is more normally known as acetic acid, and thus its esters contain "acetate" instead of "ethanoate" in their names. Other such substitutions include "formate" instead of "methanoate," "propionate" instead of "propanoate," and "butyrate" instead of "butanoate."

The chemical formulas of organic esters are typically written in the format of RCO_twoR', where R and R' are the hydrocarbon parts of the carboxylic acid and booze, respectively. For case, butyl acetate, systematically known as ethanoic acid, is derived from butanol and acetic acid and would be written CH₃CO₂C₄H₉. Culling presentations are common, including BuOAc and CH₃COOC₄H₉. Cyclic esters are known as lactones.

Construction and Bonding

Esters incorporate a carbonyl center, which gives rise to 120 degree C-C-O and O-C-O bond angles due to sp² hybridization. Different amides, esters are structurally flexible functional groups considering rotation nigh the C-O-C bonds has a lower energy barrier. Their flexibility and depression polarity affects their concrete backdrop on a macroscopic scale; they tend to be less rigid, leading to a lower melting bespeak, and more volatile, leading to a lower humid point, than the corresponding amides. The pK_a of the blastoff-hydrogens, or the hydrogens fastened to the carbon side by side to the carbonyl, on esters is effectually 25, making them essentially non-acidic except in the presence of very strong bases.

Physical Properties and Characterization

Esters are more polar than ethers, but less so than alcohols. They participate in hydrogen bonds as hydrogen bond acceptors, but cannot act as hydrogen bail donors, unlike their parent alcohols and carboxylic acids. This ability to participate in hydrogen bonding confers some water-solubility, depending on the length of the alkyl bondage attached. Since they take no hydrogens bonded to oxygens, equally alcohols and carboxylic acids do, esters do not self-associate. Consequently, esters are more volatile than carboxylic acids of similar molecular weight.

Label and Analysis

Esters are commonly identified by gas chromatography, taking advantage of their volatility. IR (infrared) spectra for esters feature an intense, sharp band in the range 1730–1750 cm⁻¹ assigned to νC=O, or vibration of the C=O bond. This peak changes depending on the functional groups attached to the carbonyl. For example, a benzene ring or double bond in conjugation with the carbonyl will bring the wavenumber downward to around 30 cm⁻ⁱ.

Reactivity

Esters react with nucleophiles at the carbonyl carbon. The carbonyl is weakly electrophilic, but is attacked past strong nucleophiles such as amines, alkoxides, hydride sources, and organolithium compounds. The carbonyl's electrophilicity can increment if it is protonated; in acidic media, an ester can be hydrolyzed past h2o to form a carboxylic acid and an booze.

The C-H bonds adjacent to the carbonyl are weakly acidic, but undergo deprotonation with strong bases. This process is the 1 that normally initiates condensation reactions. The carbonyl oxygen is weakly bones (less so than in amides), only tin can form adducts with Lewis acids.

Amines

Amines are compounds characterized by the presence of a nitrogen atom, a lone pair of electrons, and three substituents.

Learning Objectives

Identify the general backdrop of amines

Central Takeaways

Key Points

• Due to the solitary pair of electrons, amines are basic compounds. The basicity of the compound can be influenced by neighboring atoms, steric bulk, and the solubility of the corresponding cation to exist formed.
• Amine compounds can hydrogen bond, which affords them solubility in water and elevated boiling points.
• The general structure of an amine is a nitrogen atom with a lone pair of electrons and iii substituents. However, the nitrogen may bind to iv substituents, leaving a positive accuse on the nitrogen atom. These charged species tin can serve every bit intermediates for of import reactions.

Key Terms

• aliphatic: Of a grade of organic compounds in which the carbon atoms are arranged in an open up chain.
• chiral: Literally, "handedness;" refers to a chemical compound in which central atoms are bonded to multiple different substituents, such that the mirror image of the compound is non identical to the original.
• amine: Organic compounds or the functional group that contains a basic nitrogen cantlet with a lone pair.
• inversion: For a secondary or tertiary amine bonded to three different substitutents, the flipping of the iii bonds about the central N atom, resulting in the reverse stereoisomer.

The amine functional group contains a basic nitrogen cantlet with a lonely pair of electrons. As such, the group is derivative of ammonia, in which ane or more than hydrogen atoms have been replaced by a carbon-containing substituent. Compounds with the nitrogen group attached to a carbonyl within the construction are referred to as amides, and they have the structure R-CO-NR'R". Amine groups bonded to an aromatic (conjugated cyclic) structure are known equally aromatic amines. The aromatic structure finer decreases the alkalinity of the amine, while the presence of the amine grouping significantly decreases the reactivity of the ring due to an electron donating effect. The prefix "amino-" or the suffix "-amine" is used when naming an amine chemical compound. An organic compound with multiple amino groups is called a diamine, triamine, tetramine, etc.

Amine Structure

Amines are generally organized into categories based on their bonding environments. Amines that take ane of their 3 hydrogen atoms replaced by an alkyl or aromatic substituent are referred to every bit principal amines. Secondary amines are those that have ii substituents and ane hydrogen bonded to a nitrogen. Tertiary amines are amines whose hydrogens have been completely replaced past organic substituents. Finally, cyclic amines are those in which the nitrogen has been incorporated into a band structure, finer making it either a secondary or 3rd amine. The general structure of an amine contains a nitrogen atom, a solitary pair of electrons, and three substituents. However, information technology is possible to have 4 organic substituents on the nitrogen, making it an ammonium cation with a charged nitrogen center.

Third amine: The central carbon is attached to an amine grouping and three other carbon atoms.

Physical Backdrop of Amines

Amines are able to hydrogen bail. Every bit a result, the boiling points of these compounds are higher than those of the corresponding phosphines, but lower than those of the corresponding alcohols, which hydrogen bond to a stronger extent. Amines also brandish some solubility in h2o. However, the solubility decreases with an increase in carbon atoms, due to the increased hydrophobicity of the compound equally the chain length increases. Aliphatic amines, which are amines connected to an alkyl concatenation, display solubility in organic polar solvents. Aromatic amines, which are amines that participate in a conjugated ring, donate their solitary pair of electrons into the benzene band, and thus their power to engage in hydrogen bonding decreases. This results in a decrease in their solubility in water and high boiling points.

Acidity and Alkalinity of Amines

Amines of the type NHRR' and NR'R"R"' are chiral molecules and can undergo inversion. Since the barrier for inversion is quite low (~vii kcal/mol), these compounds cannot exist resolved optically. Amines are bases, and their basicity depends on the electronic properties of the substituents (alkyl groups heighten the basicity; aryl groups diminish it), steric hindrance, and the degree of solvation of the protonated amine. In full general, the effect of alkyl groups raises the energy of the solitary pair of electrons, thus elevating the basicity. Thus, the basicity of an amine can be expected to increase with the number of alkyl groups on the amine. Additionally, the issue of the effluvious ring delocalizes the solitary pair of electrons on nitrogen into the ring, resulting in decreased basicity. The solvation of protonated amines changes upon their conversion to ammonium compounds. Typically, salts of ammonium compounds exhibit the post-obit order of solubility in h2o: master ammonium (RNH_iii ⁺) > secondary ammonium (R₂NH_ii ⁺) > tertiary ammonium (R_threeNH⁺). Quaternary ammonium salts usually exhibit the lowest solubility of the serial.

Amine Preparation and Reactivity

Imine formation: A primary amine is reacted with an aldehyde to produce an imine.

Industrially, amines are prepared from ammonia by alkylation with alcohols. They tin as well be prepared via reduction of nitriles to amines using hydrogen in the presence of a nickel catalyst. Amines are quite reactive due to their basicity also equally their nucleophilicity. Virtually primary amines are expert ligands and react with metal ions to yield coordination complexes. 1 of the almost important reactions for amines is their formation of imines, or organic compounds where nitrogen participates in a double bond, upon reacting with ketones or aldehydes.

Applications of Amines

Amines are ubiquitous in biology. Many of import molecules are amine-based, such as neurotransmitters and amino acids. Their applications in the world include being starting material for dyes and models for drug design. They are also used for gas treatment, such as removing CO₂ from combustion gases.

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Source: https://courses.lumenlearning.com/boundless-chemistry/chapter/functional-group-names-properties-and-reactions/

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