Chemistry
Aldehydes and Ketones
Aldehydes and ketones are organic compounds that contain a carbonyl group, which is a carbon atom double-bonded to an oxygen atom. Aldehydes have the carbonyl group at the end of a carbon chain, while ketones have it within the chain. They are important in organic synthesis and are used in various industrial processes, including the production of plastics and pharmaceuticals.
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11 Key excerpts on "Aldehydes and Ketones"
- Morris Hein, Scott Pattison, Susan Arena, Leo R. Best(Authors)
- 2014(Publication Date)
- Wiley(Publisher)
Their structures contain the carbonyl group, C O , a carbon–oxygen double bond. Aldehydes have at least one hydrogen atom bonded to the carbonyl group, whereas ketones have only alkyl or aryl (aromatic, denoted Ar) groups bonded to the carbonyl group: Ar C H O C Ar O ketones R C H O aldehydes C R O R R C Ar O Ar In a linear expression, the aldehyde group is often written as CHO. For example, CH 3 C H O CH 3 CHO is equivalent to In the linear expression of a ketone, the carbonyl group is written as CO. For example, CH 3 CCH 3 O CH 3 COCH 3 is equivalent to The general formula for the saturated homologous series of Aldehydes and Ketones is C n H 2n O. KEY TERMS carbonyl group aldehyde ketone A second hydrogen atom bonded to a carbonyl group occurs in only one compound; formaldehyde. A Biochemical Perspective: Carbohydrates contain carbonyl groups: They can be either aldehydes or ketones. LEARNING OBJECTIVE TABLE 23.1 Why Are Aldehydes and Ketones Important to Biochemistry? Answer Comment #1 Because carbohydrates are Aldehydes and Ketones, they can form polymers. Starches and cellulose exist because of the special reactivity of the carbonyl group. #2 The genetic code is bonded in place by an important carbonyl group reaction. The well-known genetic code is a sequence of bases [adenine (A), guanine (G), thymine (T), cytosine (C)] connected to a “backbone.” The carbonyl group provides the connection. #3 The carbonyl group enables carbohydrates to form their most common structures—rings. Almost all common carbohydrate monomers exist as rings. 23.2 NAMING Aldehydes and Ketones Be able to write names and structures for both Aldehydes and Ketones. Aldehydes IUPAC RULES FOR NAMING ALDEHYDES 1. To establish the parent name, select the longest continuous chain of carbon atoms that contains the aldehyde group. 2. The carbons of the parent chain are numbered starting with the aldehyde group. Since the aldehyde group is at the beginning (or end) of a chain, it is always number 1.
eBook - PDFChemistry for Today
General, Organic, and Biochemistry
- Spencer Seager, Michael Slabaugh, Maren Hansen, , Spencer Seager, Spencer Seager, Michael Slabaugh, Maren Hansen(Authors)
- 2021(Publication Date)
- Cengage Learning EMEA(Publisher)
(Section 14.4) iStock.com/shapecharge Copyright 2022 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Aldehydes and Ketones 447 THE CARBONYL FUNCTIONAL GROUP is characteristic of both Aldehydes and Ketones. In a carbonyl group, a carbon is double bonded to an oxygen atom and single bonded to two other atoms: O C carbonyl group Aldehydes and Ketones occur widely in nature and play important roles in living or- ganisms. For example, the carbonyl group is found in numerous carbohydrates, in- cluding glucose and fructose. Glucose, a major source of energy in living systems, is found combined with fructose in cane sugar: H O C H — C — OH HO — C — H H — C — OH H — C — OH CH 2 — OH carbonyl group CH 2 — OH C — O HO — C — H H — C — OH H — C — OH CH 2 — OH carbonyl group — fructose glucose In this chapter, we will study the naming of Aldehydes and Ketones, as well as some of their important reactions. These concepts will be very useful when we study the chemistry of carbohydrates in Chapter 17. 14.1 The Nomenclature of Aldehydes and Ketones Learning Objective 1 Recognize the carbonyl group in compounds and classify the compounds as aldehydes or ketones. Learning Objective 2 Assign IUPAC names to Aldehydes and Ketones. When a carbonyl group is directly bonded to at least one hydrogen atom, the compound is an aldehyde. In ketones, two carbon atoms are directly bonded to the carbonyl group: H O carbonyl group C O aldehyde C O C ketone C C O C The group. carbonyl group A compound that contains the group; the general formula is H O C H.
eBook - PDF- David R. Klein(Author)
- 2020(Publication Date)
- Wiley(Publisher)
Aldehydes and Ketones are responsible for many flavors and odors that you will readily recognize: O H HO H 3 CO Vanillin (Vanilla flavor) H O Cinnamaldehyde (Cinnamon flavor) O (R)-Carvone (Spearmint flavor) H O Benzaldehyde (Almond flavor) Many important biological compounds also exhibit the carbonyl group, including progesterone and testosterone, the female and male sex hormones. O O H H H Progesterone O OH H Testosterone H H Simple Aldehydes and Ketones are industrially important; for example: O H H Formaldehyde O Acetone CH 3 H 3 C Formaldehyde is used as a preservative in some vaccine formulations, while acetone is used as a sol- vent and is commonly found in nail polish remover. Aldehydes and Ketones are also used as building blocks in the syntheses of commercially important compounds, including pharmaceuticals and poly- mers. Compounds containing a carbonyl group react with a large variety of nucleophiles, affording a wide range of possible products. Due to the versatile reactivity of the carbonyl group, Aldehydes and Ketones occupy a central role in organic chemistry. DO YOU REMEMBER? Before you go on, be sure you understand the following topics. If necessary, review the suggested sections to prepare for this chapter. • Retrosynthetic Analysis (Section 12.5) • Grignard Reagents (Section 13.6) • Oxidation of Alcohols (Section 13.10) 890 CHAPTER 20 Aldehydes and Ketones 20.2 NOMENCLATURE Nomenclature of Aldehydes Recall that four discrete steps are required to name most classes of organic compounds (as we saw with alkanes, alkenes, alkynes, and alcohols): 1. Identify and name the parent. 2. Identify and name the substituents. 3. Assign a locant to each substituent. 4. Assemble the substituents alphabetically. Aldehydes are also named using the same four-step procedure.
eBook - PDF- David R. Klein(Author)
- 2016(Publication Date)
- Wiley(Publisher)
19.1 Introduction to Aldehydes and Ketones 19.2 Nomenclature 19.3 Preparing Aldehydes and Ketones: A Review 19.4 Introduction to Nucleophilic Addition Reactions 19.5 Oxygen Nucleophiles 19.6 Nitrogen Nucleophiles 19.7 Hydrolysis of Acetals, Imines, and Enamines 19.8 Sulfur Nucleophiles 19.9 Hydrogen Nucleophiles 19.10 Carbon Nucleophiles 19.11 Baeyer–Villiger Oxidation of Aldehydes and Ketones 19.12 Synthesis Strategies 19.13 Spectroscopic Analysis of Aldehydes and Ketones 19 Aldehydes and Ketones DID YOU EVER WONDER . . . why beta-carotene, which makes carrots orange, is reportedly good for your eyes? T his chapter will explore the reactivity of Aldehydes and Ketones. Specifically, we will see that a wide variety of nucleophiles will react with Aldehydes and Ketones. Many of these reactions are common in biological pathways, including the role that beta-carotene plays in promoting healthy vision. As we will see several times in this chapter, the reactions of Aldehydes and Ketones are also cleverly exploited in the design of drugs. The reactions and principles outlined in this chapter are central to the study of organic chemistry and will be used as guid- ing principles throughout the remaining chapters of this textbook. 19.1 Introduction to Aldehydes and Ketones 845 19.1 Introduction to Aldehydes and Ketones Aldehydes (RCHO) and ketones (R 2 CO) are similar in structure in that both classes of compounds possess a C = O bond, called a carbonyl group: O Carbonyl group O R H An aldehyde R R A ketone The carbonyl group of an aldehyde is flanked by a hydrogen atom, while the carbonyl group of a ketone is flanked by two carbon atoms.
eBook - PDF- T. W. Graham Solomons, Craig B. Fryhle, Scott A. Snyder(Authors)
- 2022(Publication Date)
- Wiley(Publisher)
See the online course materials in for additional examples, videos, and practice. 16.1 Introduction • Aldehydes have a carbonyl group bonded to a carbon atom on one side and a hydrogen atom on the other side. (Formaldehyde is an exception because it has hydrogen atoms on both sides.) • Ketones have a carbonyl group bonded to carbon atoms on both sides. RCOR′ RCHO General formulas for aldehydes General formulas for ketones R H O R R′ O Although earlier chapters have given us some insight into the chemistry of carbonyl com- pounds, we shall now consider their chemistry in detail. The reason: the chemistry of the carbonyl group is central to the chemistry of most of the chapters that follow. In this chapter we focus our attention on the preparation of Aldehydes and Ketones, their physical properties, and especially nucleophilic addition reactions at their carbonyl groups. Acetone 16.2 Nomenclature of Aldehydes and Ketones • Aliphatic aldehydes are named substitutively in the IUPAC system by replacing the final -e of the name of the corresponding alkane with -al. Since the aldehyde group must be at an end of the carbon chain, there is no need to indicate its position. When other substituents are present the carbonyl group carbon is assigned position 1. Many aldehydes also have common names; these are given below in parentheses. These com- mon names are derived from the common names for the corresponding carboxylic acids (Sec- tion 17.2A), and some of them are retained by the IUPAC as acceptable names. Methanal (formaldehyde) Ethanal (acetaldehyde) Propanal (propionaldehyde) 5-Chloropentanal Phenylethanal (phenylacetaldehyde) H O H H O H O Cl H O H O • Aldehydes in which the —CHO group is attached to a ring system are named substitu- tively by adding the suffix carbaldehyde. Several examples follow: Benzenecarbaldehyde (benzaldehyde) H O Cyclohexanecarbaldehyde H O 2-Naphthalenecarbaldehyde H O
eBook - PDF- H. Stephen Stoker(Author)
- 2015(Publication Date)
- Cengage Learning EMEA(Publisher)
C O O O B O O O CH 2 CH 2 CH 2 O CH 3 CH 3 Copyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 132 CHAPTER 4 Aldehydes and Ketones Aldehydes and Ketones are related to alcohols in the same manner that alkenes are related to alkanes. Removal of hydrogen atoms from each of two adjacent carbon atoms in an alkane produces an alkene. In a like manner, removal of a hydrogen atom from the ! OH group of an alcohol and from the carbon atom to which the hydroxyl group is attached produces a carbonyl group (see Figure 4-1). Figure 4-1 Aldehydes and Ketones are related to alcohols in the same manner that alkenes are related to alkanes; removal of two hydrogen atoms produces a double bond. H O C O C – 2 H H Alcohol Aldehyde or ketone Alkane Alkene H C C C C – 2 H H a b Formation of a carbon– oxygen double bond Formation of a carbon– carbon double bond 1. In an aldehyde the carbonyl group a. is always located at the end of the carbon chain b. may be at the end of or in an interior position on the carbon chain c. is always located in an interior position on the carbon chain d. no correct response 2. In a ketone the carbonyl group a. is always located at the end of the carbon chain b. may be at the end of or in an interior position on the carbon chain c. is always located in an interior position on the carbon chain d. no correct response 3. Which of the following is a generalized linear structural designation for an aldehyde? a. RCOH b. RCHO c. RCOR d. no correct response Section 4-3 Quick Quiz Answers: 1.
eBook - PDFGeneral, Organic, and Biological Chemistry
An Integrated Approach
- Kenneth W. Raymond(Author)
- 2012(Publication Date)
- Wiley(Publisher)
When naming Aldehydes and Ketones according to the IUPAC rules, the carbonyl group (C “ O) must be part of the parent chain, which is numbered from the end nearer this group. Since the carbonyl carbon atom of an aldehyde is always in position number 1, its position is not specified in the name. For ketones, however, the position of the carbonyl carbon is given, unless the molecule is small enough that there is no question as to carbonyl placement. Parent chains are named by dropping the final “e” from the name of the corresponding hydrocarbon and adding “al” for aldehydes or “one” for ketones (Figure 9.7). The common names of ketones are formed by placing “ketone” after the names of the alkyl groups attached to the carbonyl carbon atom. For aldehydes and for some ketones, other common names are assigned. Three important ones to know are formaldehyde (methanal), acetaldehyde (ethanal), and acetone (propanone) (Figure 9.7). you have decided on the reaction type, think about the different rules that apply: How do different types of alcohols respond to oxidation and which is the major alkene product expected from dehydration? SOLUTION a. K 2 Cr 2 O 7 CH 3 CH 2 CH 2 OH CH 3 CH 2 C¬OH O ‘ b. K 2 Cr 2 O 7 CH 3 CHCH 3 OH ƒ CH 3 CCH 3 O ‘ c. H + heat CH 3 CH 2 CH 2 OH CH 3 CH“CH 2 d. H + heat CH 3 CH“CH 2 CH 3 CHCH 3 OH ƒ PRACTICE PROBLEM 9.5 Draw the organic product (if any) expected from each reaction. a. K 2 Cr 2 O 7 OH CH 3 d. H + heat OH CH 3 b. K 2 Cr 2 O 7 CH 2 OH e. CH 2 OH H + heat c. K 2 Cr 2 O 7 OH CH 3 f. OH CH 3 H + heat 9.4 Aldehydes and Ketones 345 Aldehydes and Ketones have much lower boiling points than alcohols with a similar molecular weight. Ethanol, for example, has a boiling point of 78.5°C, while ethanal has a boiling point of 20°C (Table 9.2). The difference in boiling points is due to dif- ferences in how the molecules are attracted to one another.
eBook - PDF- T. W. Graham Solomons, Craig B. Fryhle, Scott A. Snyder(Authors)
- 2017(Publication Date)
- Wiley(Publisher)
(Formaldehyde is an exception because it has hydrogen atoms on both sides.) • Ketones have a carbonyl group bonded to carbon atoms on both sides. RCOR′ RCHO General formulas for aldehydes General formulas for ketones R H O R R′ O Although earlier chapters have given us some insight into the chemistry of carbonyl compounds, we shall now consider their chemistry in detail. The reason: the chemistry of the carbonyl group is central to the chemistry of most of the chapters that follow. In this chapter we focus our attention on the preparation of Aldehydes and Ketones, their physical properties, and especially nucleophilic addition reactions at their carbonyl groups. 16.1 INTRODUCTION Acetone 16.2 NOMENCLATURE OF Aldehydes and Ketones • Aliphatic aldehydes are named substitutively in the IUPAC system by replacing the final -e of the name of the corresponding alkane with -al. Since the aldehyde group must be at an end of the carbon chain, there is no need to indi- cate its position. When other substituents are present the carbonyl group carbon is assigned position 1. Many aldehydes also have common names; these are given below in parentheses. These common names are derived from the common names for the corresponding carboxyl- ic acids (Section 17.2A), and some of them are retained by the IUPAC as acceptable names. Methanal (formaldehyde) Ethanal (acetaldehyde) Propanal (propionaldehyde) 5-Chloropentanal Phenylethanal (phenylacetaldehyde) H O H H O H O Cl H O H O • Aldehydes in which the − CHO group is attached to a ring system are named sub- stitutively by adding the suffix carbaldehyde. Several examples follow: Benzenecarbaldehyde (benzaldehyde) H O Cyclohexanecarbaldehyde H O 2-Naphthalenecarbaldehyde H O 16.2 NOMENCLATURE OF Aldehydes and Ketones 713 The common name benzaldehyde is far more frequently used than benzenecarbalde- hyde for C 6 H 5 CHO, and it is the name we shall use in this text.
eBook - ePub- Robert J. Ouellette, J. David Rawn(Authors)
- 2015(Publication Date)
- Elsevier(Publisher)
Figure 10.2 ). The relationship between structure and the physiological response of odor depends upon their interactions with membrane proteins in neurons called guanine nucleoside coupled protein receptors (GCPRs).Figure 10.2 Structures of Naturally Occurring Aldehydes and KetonesAt one time the extraction of fragrant compounds from flowers and other plants was the sole source of materials for products such as perfumes. However, it is now more economical to synthesize these compounds in the laboratory. Chemical synthesis also allows for the production of compounds with new odors.10.2 Nomenclature of Aldehydes and Ketones
Common Names of Aldehydes and Ketones
Aldehydes and Ketones with low molecular weights are often referred to by their common names. The names of aldehydes are derived from the common names of related acids (Chapter 12 ).IUPAC Names of Aldehydes
1.Aldehydes are named by IUPAC rules similar to those outlined for alcohols. The final -e of the parent hydrocarbon corresponding to the aldehyde is replaced by the ending -al .2.The aldehyde functional group has a higher priority than alkyl, halogen, hydroxyl, and alkoxy groups. The names and positions of these groups are indicated as prefixes to the name of the parent aldehyde.3.The aldehyde functional group has a higher priority than double or triple bonds. When the parent chain contains a double or triple bond, replace the final -e of the name of the parent alkene or alkyne with the suffix -al
- David R. Klein(Author)
- 2017(Publication Date)
- Wiley(Publisher)
There are only two ways to connect three carbon atoms (without a ring or a bond), shown here: Therefore, there are only two aldehydes with the molecular formula C4H8O, shown here: 19.47. The molecular formula (C5H10O) indicates one degree of unsaturation (see Section 14.16), which accounts for the carbonyl group of an aldehyde: Since there is only one degree of unsaturation (which has now been accounted for), the remaining four carbon atoms do not comprise a ring and do not possess any bonds. There are only four ways to connect four carbon atoms (without a ring or a bond), shown here: Therefore, there are only four aldehydes with the molecular formula C5H10O, shown here. One of these aldehydes exhibits a chiral center (highlighted): 19.48. The molecular formula (C6H12O) indicates one degree of unsaturation (see Section 14.16), which accounts for the carbonyl group of a ketone: Since there is only one degree of unsaturation (which has now been accounted for), the remaining five carbon atoms do not comprise a ring and do not possess any bonds. Now let’s consider all of the different unique ways of connecting five carbon atoms around a carbonyl group. We can immediately rule out any isomers for which we place all five carbon atoms on one side of the carbonyl group, as that would generate an aldehyde, not a ketone. So, either there are four carbon atoms on one side of the carbonyl group and one carbon atom on the other side, OR, there are two carbon atoms on one side and three carbon atoms on the other side. We must explore each of these possibilities. If we first consider having two carbon atoms on one side and three carbon atoms on the other side, there are only two such isomers, shown here: Now we consider having four carbon atoms on one side of the carbonyl group and one carbon atom on the other side. The side with four carbon atoms can be arranged in one of four possible ways, shown here, giving rise to four more isomers:
eBook - PDFOrganic Reaction Mechanisms 2017
An annual survey covering the literature dated January to December 2017
- A. C. Knipe, Mark G. Moloney, A. C. Knipe, Mark G. Moloney(Authors)
- 2020(Publication Date)
- Wiley(Publisher)
1 1 Reactions of Aldehydes and Ketones and their Derivatives S. R. Hussaini Department of Chemistry and Biochemistry, The University of Tulsa, Tulsa, OK, United States CHAPTER MENU Formation and Reactions of Acetals and Related Species, 2 Reactions of Glucosides, 3 Reactions of Ketenes, 7 Formation and Reactions of Nitrogen Derivatives, 8 Imines: General, Synthesis, and Iminium Chemistry, 8 Mannich, Mannich-type, and nitro-Mannich Reactions, 11 Other ‘Name’ Reactions of Imines, 11 Alkylations, 11 Miscellaneous Additions to Imines, 14 Oxidation and Reduction of Imines, 14 Other Reactions of Imines, 17 Oximes, Hydrazones, and Related Species, 23 C–C Bond Formation and Fission: Aldol and Related Reactions, 30 Asymmetric Aldol Reactions, 31 The Mukaiyama Aldol, 31 Other Aldol and Aldol-type Reactions, 33 Alkynylations, 36 Michael Addition and Miscellaneous Condensations, 36 Other Addition Reactions, 43 Arylations, 44 Addition of Other Organometallics, including Grignards, 44 The Wittig, Julia-Kocienski, Peterson, and Other Olefinations, 44 Hydrophosphonylation, Hydroboration, and Addition of Isocyanide, 46 Miscellaneous Additions, 46 Enolization, Reactions of Enolates, and Related Reactions, 50 𝛼 -Substitutions, 50 Oxidation and Reduction of Carbonyl Compounds, 51 Oxidation of Aldehydes to Amides and Nitriles, 51 Decarbonylation Reactions, 51 Miscellaneous Oxidative Processes, 53 Stereoselective Reduction Reactions, 57 Other Reactions, 59 References, 59 Organic Reaction Mechanisms 2017, First Edition. Edited by A. C. Knipe and M. G. Moloney. © 2020 John Wiley & Sons Ltd. Published 2020 by John Wiley & Sons Ltd. 2 Organic Reaction Mechanisms 2017 Formation and Reactions of Acetals and Related Species Novel nitrated [6,6,6]-tricyclic acetal or ketals are prepared by an intramolecular annulation of o -carbonyl allylbenzenes. The proposed mechanism involves olefinic nitration, bis-cyclization, and tautomerization, followed by another nitration.
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