It also causes the higher boiling points of carbonyl compounds. The carboxyl group is an organic functional group consisting of a carbon atom double bonded to an oxygen atom and single bonded to a hydroxyl group. Therefore, a carboxyl group is a combination of a carbonyl group and a hydroxyl group.
The chemical formula of carboxyl group is —COOH. Figure 2: Chemical Structure of Carboxyl Group. The major class of compounds containing carboxyl groups is carboxylic acids. Carboxylic acids consist of a carboxyl group bonded to either a hydrogen atom or an alkyl group. Dicarboxylic acids are compounds containing two carboxylic acids. Carboxyl group can ionize releasing a proton hydrogen atom from a hydroxyl group.
Since this proton is released as a free proton, carboxylic acids are acids. When the proton is released, the oxygen atom of the hydroxyl group gets a negative charge.
This negative charge is stabilized by sharing the electrons of this oxygen atom with the other oxygen atom of the carboxyl group. Therefore, the ionized form is stable. Compounds containing carboxyl groups can form dimers. Draw the Lewis structure for the ester formed from the reaction of butyric acid with 2-propanol.
A ketone contains a group bonded to two additional carbon atoms; thus, a minimum of three carbon atoms are needed. Since they are both carboxylic acids, they each contain the —COOH functional group and its characteristics. The difference is the hydrocarbon chain in a saturated fatty acid contains no double or triple bonds, whereas the hydrocarbon chain in an unsaturated fatty acid contains one or more multiple bonds.
Skip to content Chapter Organic Chemistry. Learning Objectives By the end of this section, you will be able to: Describe the structure and properties of aldehydes, ketones, carboxylic acids and esters. Example 1 Oxidation and Reduction in Organic Chemistry Methane represents the completely reduced form of an organic molecule that contains one carbon atom. Answer: a reduced bond to oxygen atom replaced by bond to hydrogen atom ; b oxidized one bond to hydrogen atom replaced by one bond to oxygen atom ; c oxidized 2 bonds to hydrogen atoms have been replaced by bonds to an oxygen atom.
Chemistry End of Chapter Exercises Order the following molecules from least to most oxidized, based on the marked carbon atom: Predict the products of oxidizing the molecules shown in this problem. In each case, identify the product that will result from the minimal increase in oxidation state for the highlighted carbon atom: a b c Predict the products of reducing the following molecules.
In each case, identify the product that will result from the minimal decrease in oxidation state for the highlighted carbon atom: a b c Explain why it is not possible to prepare a ketone that contains only two carbon atoms.
How does hybridization of the substituted carbon atom change when an alcohol is converted into an aldehyde? An aldehyde to a carboxylic acid? Fatty acids are carboxylic acids that have long hydrocarbon chains attached to a carboxylate group. How does a saturated fatty acid differ from an unsaturated fatty acid? How are they similar? Write a condensed structural formula, such as CH 3 CH 3 , and describe the molecular geometry at each carbon atom. Write the two-resonance structures for the acetate ion.
Write two complete, balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures: a ethanol reacts with propionic acid b benzoic acid, C 6 H 5 CO 2 H, is added to a solution of sodium hydroxide Write two complete balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures. What is the percent yield of a process that produces Anyhow, these cannot make stronger hydrogen bonds like alcohols resulting lower boiling points than the corresponding alcohols.
Because of the hydrogen bond formation ability, low molecular weight aldehydes and ketones are soluble in water. However, when the molecular weight increases, they become hydrophobic. The carbonyl carbon atom is partially positive charged, hence can act as an electrophile. Therefore, these molecules are easily subjected to nucleophilic substitution reactions. The hydrogens attached to the carbon next to the carbonyl group has acidic nature, which accounts for various reactions of aldehydes and ketones.
Compounds containing carbonyl groups are widely occurring in nature. Cinnamaldehyde in cinnamon bark , vanillin in vanilla bean , camphor camphor tree , and cortisone adrenal hormone are some of the natural compounds with a carbonyl group.
Since they have no hydrogens bonded to oxygens, as alcohols and carboxylic acids do, esters do not self-associate. Consequently, esters are more volatile than carboxylic acids of similar molecular weight. Esters are usually identified by gas chromatography, taking advantage of their volatility. This peak changes depending on the functional groups attached to the carbonyl. Esters react with nucleophiles at the carbonyl carbon. The carbonyl is weakly electrophilic, but is attacked by strong nucleophiles such as amines, alkoxides, hydride sources, and organolithium compounds.
The C-H bonds adjacent to the carbonyl are weakly acidic, but undergo deprotonation with strong bases. This process is the one that usually initiates condensation reactions.
The carbonyl oxygen is weakly basic less so than in amides , but can form adducts with Lewis acids. Amines are compounds characterized by the presence of a nitrogen atom, a lone pair of electrons, and three substituents. The amine functional group contains a basic nitrogen atom with a lone pair of electrons. As such, the group is derivative of ammonia, in which one or more hydrogen atoms have been replaced by a carbon-containing substituent. Amine groups bonded to an aromatic conjugated cyclic structure are known as aromatic amines.
The aromatic structure effectively decreases the alkalinity of the amine, while the presence of the amine group significantly decreases the reactivity of the ring due to an electron donating effect. An organic compound with multiple amino groups is called a diamine, triamine, tetramine, etc. Amines are generally organized into categories based on their bonding environments.
Amines that have one of their three hydrogen atoms replaced by an alkyl or aromatic substituent are referred to as primary amines. Secondary amines are those that have two substituents and one hydrogen bonded to a nitrogen. Tertiary amines are amines whose hydrogens have been completely replaced by organic substituents. Finally, cyclic amines are those in which the nitrogen has been incorporated into a ring structure, effectively making it either a secondary or tertiary amine.
The general structure of an amine contains a nitrogen atom, a lone pair of electrons, and three substituents. However, it is possible to have four organic substituents on the nitrogen, making it an ammonium cation with a charged nitrogen center. Tertiary amine : The central carbon is attached to an amine group and three other carbon atoms. Amines are able to hydrogen bond. As 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 display some solubility in water. However, the solubility decreases with an increase in carbon atoms, due to the increased hydrophobicity of the compound as the chain length increases. Aliphatic amines, which are amines connected to an alkyl chain, display solubility in organic polar solvents.
Aromatic amines, which are amines that participate in a conjugated ring, donate their lone pair of electrons into the benzene ring, and thus their ability to engage in hydrogen bonding decreases.
This results in a decrease in their solubility in water and high boiling points. Amines are bases, and their basicity depends on the electronic properties of the substituents alkyl groups enhance the basicity; aryl groups diminish it , steric hindrance, and the degree of solvation of the protonated amine. In general, the effect of alkyl groups raises the energy of the lone 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 effect of the aromatic ring delocalizes the lone pair of electrons on nitrogen into the ring, resulting in decreased basicity.
The solvation of protonated amines changes upon their conversion to ammonium compounds. Quaternary ammonium salts usually exhibit the lowest solubility of the series. 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 can also 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 as well as their nucleophilicity. Most primary amines are good ligands and react with metal ions to yield coordination complexes. One of the most 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. Amines are ubiquitous in biology.
Many important 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 CO 2 from combustion gases. Privacy Policy. Skip to main content. Organic Chemistry. Search for:. Functional Group Names, Properties, and Reactions Functional Groups Functional groups refer to specific atoms bonded in a certain arrangement that give a compound certain physical and chemical properties.
Functional groups will undergo the same type of reactions regardless of the compound of which they are a part; however, the presence of certain functional groups within close proximity can limit reactivity. Functional groups can be used to distinguish similar compounds from each other. Key Terms functional group : A specific grouping of elements that is characteristic of a class of compounds, and determines some properties and reactions of that class.
Alcohols Alcohols are functional groups characterized by the presence of an -OH group. Learning Objectives Identify the general properties of the alcohol functional group. This leads to higher boiling points compared to their parent alkanes.
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