Chemistry
Carbonyl Group
The carbonyl group is a functional group in organic chemistry consisting of a carbon atom double-bonded to an oxygen atom. It is commonly found in aldehydes, ketones, carboxylic acids, and their derivatives. The presence of the carbonyl group imparts unique chemical and reactivity properties to organic compounds, making it a key feature in many organic reactions.
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7 Key excerpts on "Carbonyl Group"
eBook - PDF- Metin Balcı(Author)
- 2021(Publication Date)
- Wiley-VCH(Publisher)
181 5 Carbonyl Compounds The Carbonyl Group and its chemistry are a significant part of organic chemistry. Most biological and natural compounds contain carbonyl functionality. Particularly with the addition of heteroatoms to carbon–oxygen double bonds (C=O), some new functional groups can be designed. Condensation reactions that provide the formation of new carbon—carbon bonds play an essential role in carbonyl chemistry. The reactions of the Carbonyl Group can be perceived as very comprehensive and complicated at first. However, when the reactivity of the Carbonyl Group and the reaction mechanism are studied in depth, it is seen that almost all of these reactions occur via the same mechanism. For example, the commonly known condensation reactions (ester condensation, aldol condensation, Knoevenagel condensation, Perkin condensation, etc.) all proceed by the same mechanism. They are referred to by different names according to the starting compound used. If the characteristic features of these reactions are understood, it will be seen that Carbonyl Group chemistry is a straightforward and enjoyable subject. Before starting to examine the reactions of the Carbonyl Group, it is necessary to understand the reactivity of the Carbonyl Group. As discussed in previous sections, in order for a chemical reaction to occur, the polarization of bond electrons is required on one side of a molecule with a high electron density and a low electron density on the other. For example, in nucleophilic substitution reactions, we saw that carbon—halogen (C—X) bonds are polarized and nucleophiles attack the carbon atom. 5.1 Reactivity of the Carbonyl Group The Carbonyl Group consists of a σ bond and a π bond between the carbon and the oxygen atom. The carbonyl carbon atom and the oxygen atom are sp 2 -hybridized. Three atoms are connected to the carbonyl carbon atom. All those atoms lie in a plane and the bond angles are approximately 120 ∘ .
eBook - ePub- Metin Balcı(Author)
- 2021(Publication Date)
- Wiley-VCH(Publisher)
5 Carbonyl CompoundsThe Carbonyl Group and its chemistry are a significant part of organic chemistry. Most biological and natural compounds contain carbonyl functionality. Particularly with the addition of heteroatoms to carbon–oxygen double bonds (C=O), some new functional groups can be designed. Condensation reactions that provide the formation of new carbon—carbon bonds play an essential role in carbonyl chemistry. The reactions of the Carbonyl Group can be perceived as very comprehensive and complicated at first. However, when the reactivity of the Carbonyl Group and the reaction mechanism are studied in depth, it is seen that almost all of these reactions occur via the same mechanism. For example, the commonly known condensation reactions (ester condensation, aldol condensation, Knoevenagel condensation, Perkin condensation, etc.) all proceed by the same mechanism. They are referred to by different names according to the starting compound used. If the characteristic features of these reactions are understood, it will be seen that Carbonyl Group chemistry is a straightforward and enjoyable subject.Before starting to examine the reactions of the Carbonyl Group, it is necessary to understand the reactivity of the Carbonyl Group. As discussed in previous sections, in order for a chemical reaction to occur, the polarization of bond electrons is required on one side of a molecule with a high electron density and a low electron density on the other. For example, in nucleophilic substitution reactions, we saw that carbon—halogen (C—X) bonds are polarized and nucleophiles attack the carbon atom.5.1 Reactivity of the Carbonyl Group
The Carbonyl Group consists of a σ bond and a π bond between the carbon and the oxygen atom. The carbonyl carbon atom and the oxygen atom are sp2 -hybridized. Three atoms are connected to the carbonyl carbon atom. All those atoms lie in a plane and the bond angles are approximately 120°. The p orbitals perpendicular to this plane, one on carbon and the other on oxygen, form the π bond. The oxygen atom has two pairs of nonbonding electrons. They occupy the remaining sp2
eBook - PDF- H. Stephen Stoker(Author)
- 2015(Publication Date)
- Cengage Learning EMEA(Publisher)
The carbon atom of a Carbonyl Group must form two other bonds in addition to the carbon–oxygen double bond in order to have four bonds. The nature of these two additional bonds determines the type of carbonyl-containing compound it is. There are five major classes of carbonyl-containing hydrocarbon derivatives that are considered in this text. ◀ 1. Aldehydes. In an aldehyde, one of the two additional bonds that the carbonyl carbon atom forms must be to a hydrogen atom. The other may be to a hydrogen atom, an alkyl or cycloalkyl group, or an aromatic ring system. Aldehyde functional group Simplest aldehyde Other examples of aldehydes C O O H O B C O O H H O B H C O O O B C O O H O B CH 3 CH 2 O 2. Ketones. In a ketone, both of the additional bonds of the carbonyl carbon atom must be to another carbon atom that is part of an alkyl, cycloalkyl, or aromatic group. C O O H 3 C CH 3 O B Ketone functional group Simplest ketone Other examples of ketones C O O C O B C C O O O H 3 C CH 2 CH 3 O B CH 3 O C O O B ▶ The difference in electronega-tivity between oxygen and carbon causes a carbon–oxygen double bond to be polar. ▶ The word carbonyl is pro-nounced “carbon-EEL.” 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. 130 CHAPTER 4 Aldehydes and Ketones 3. Carboxylic acids. In a carboxylic acid, one of the two additional bonds of the carbonyl carbon atom must be to a hydroxyl group, and the other may be to a hydro-gen atom, an alkyl or cycloalkyl group, or an aromatic ring system.
eBook - PDF- Ramesh Chandra, Snigdha Singh, Aarushi Singh(Authors)
- 2019(Publication Date)
- Arcler Press(Publisher)
Carbonyl Group Reactions 8 CONTENTS 8.1. Introduction .................................................................................... 252 8.2. The Occurrence Of Aldehydes And Ketones .................................... 254 8.3. Synthetic Preparation Of Aldehydes And Ketones ............................ 255 8.4. Properties Of Aldehydes And Ketones ............................................. 256 8.5. Reactions Of Aldehydes And Ketones ............................................. 259 8.6. Reduction Reactions ....................................................................... 264 8.7. Oxidation Reactions ....................................................................... 266 References ............................................................................................. 268 Organic Reactions and their nomenclature 252 8.1. INTRODUCTION Ketones and aldehydes organic compounds which integrate a carbonyl functional group , C=O. The carbon atom of this assembly has two residual bonds that may be engaged by hydrogen or aryl or alkyl substituents. The compound is an aldehyde if in any case one of these substituents is hydrogen. The compound is a ketone if neither is hydrogen, (Jencks, 1964; Burgi et al., 1974; Mikami et al., 2004). Figure 8.1: The organic structure of Carbonyl Group. [Source: https://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/aldket1. htm] A characteristic suffix is assigned to these classes by the IUPAC system of nomenclature, one to ketones and al to aldehydes. For instance, H 2 C=O is methanal, more frequently called formaldehyde. Since an aldehyde Carbonyl Group essentially always lie at the termination of a carbon chain, it is by defaulting location #1, and consequently describes the numbering course (Brown et al., 1939; Noyce & Jorgenson, 1962; Kawabata et al., 1991). A ketone carbonyl function may be situated anyplace within a ring or chain, and its location is assumed by a locator number.
eBook - PDF- John M. McIntosh(Author)
- 2018(Publication Date)
- De Gruyter(Publisher)
This means the acid catalyst is gone and the nitrogen atom, being positively charged, is no longer nucleophilic. 7.8 Introduction to Carbonyl Groups The molecules to be studied now all contain a carbon–oxygen double bond. This group is called a carbonyl (carbon-eel’) group and it forms part of several different, but closely related, functional groups. The mechanism we have developed for the reaction of carbon-carbon double bonds (electrophilic addition) might seem to be applicable here also. However, the change from carbon to oxygen is a significant one and the process must be revised. 7.9 The Carbonyl Group – Nucleophilic Addition The Carbonyl Group consists of one sp 2 -hybridized carbon atom attached by a double bond to one oxygen atom (Fig. 7.6). Let us look at this structure more closely to see if we can predict what type of reactions it might undergo. Since sp 2 -hybridized carbon 7.9 The Carbonyl Group – Nucleophilic Addition | 123 is planar, the four atom system A, B, C, and O must all lie in the same plane. Oxygen is more electronegative than carbon and therefore the C = O bond will be polarized to-ward oxygen leaving a partial positive ( δ + ) charge on the carbonyl carbon atom. We would then predict that nucleophiles would tend to react at carbon and electrophiles at oxygen. This basic fact controls almost all of the chemistry of groups that contain the Carbonyl Group. C O A B C O δ δ Fig. 7.6 If a nucleophile attacks the positive carbon and forms a bond to it with its pair of elec-trons, one of the existing four bonds must be broken. However, when the carbonyl π bond is broken, the oxygen atom remains attached (Fig. 7.7). Notice that the carbon changes its hybridization from sp 2 to sp 3 . Thus, this is an addition reaction but it is different to the addition reactions studied in Chapter 5. This one is initiated by a nu-cleophile and is called a nucleophilic addition.
eBook - PDFOrganic Chemistry
A Mechanistic Approach
- Penny Chaloner(Author)
- 2014(Publication Date)
- CRC Press(Publisher)
4.15(c) Acetic acid—molecules are held together by hydrogen bonds. Key Points from Section 4.5 • All carbonyl compounds involve a polar carbon–oxygen double bond, and both atoms are sp 2 hybridized. The oxygen atom bears two lone pairs of electrons. • Aldehydes have a formula RC( =O)H (also written RCHO) and a nomenclature suffix -al. The carbonyl carbon atom is C-1. • Ketones have a formula R 2 C =O and a nomenclature suffix -one. The chain is numbered to give the carbonyl carbon atom the lowest number. • Acid derivatives include carboxylic acids, RC( =O)OH, suffix -oic acid, esters RC( =O)OR′ , suffix -oate; amides, R(C =O)NH 2 or RC( =O)NR 2 ′ , suffix, -amide, acid chlorides, RC( =O)Cl, suffix -oyl chloride; anhydrides RC( =O)OC( =O)R′ , suffix -oic anhydride. • All carbonyl compounds can act as hydrogen-bond acceptors. Carboxylic acids and amides are also excellent hydrogen-bond donors. 104 4.6 Priorities in Nomenclature 4.6 PRIORITIES IN NOMENCLATURE We have mostly so far looked at molecules containing just one functional group—but of course, many really interesting compounds contain more than one. We need to have a system that allows us to prioritize. If a molecule contains both a carboxylic acid and a ketone, do we name it as an acid or as a ketone? The IUPAC rules tell us to name it as an acid—so 4.62 is 4-oxoheptanoic acid. Table 4.4 summarizes the ordering of groups and how they are named when they are a substitu- ent on a molecule containing a higher priority group. In general, you will see that the more highly oxidized the functional group, the higher up the table it appears. There is neither any prospect, nor any need, to learn all the IUPAC rules in one go (they run to several volumes, and there are various classes we have not dealt with, because we will encounter them infrequently), and later chapters will give review problems to remind you of the way we name the molecules that chapter deals with.
eBook - PDFMethods for Oxidation of Organic Compounds V2
Alcohols, Alcohol Derivatives, Alky Halides, Nitroalkanes, Alkyl Azides, Carbonyl Compounds Hydroxyarenes and Aminoarenes
- Alan Haines(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
-6 -Oxidation of Carbonyl Compounds The oxidation of aldehydes (alkanals) and ketones (alkanones) has been reviewed [1], and there is an extensive compilation, based on reagent type, of methods for the oxidation of most classes of organic compounds, including carbonyl compounds [2,3]. Books [4,5] and a broadly based review article [6] on carboxylic acids and their derivatives provide valuable sources of references to literature on the oxidation of carbonyl compounds. REFERENCES [1] H. S. Verter, in The Chemistry of Functional Groups. The Chemistry of the Carbonyl Group (ed. J. Zabicky), Vol. 2, pp. 71-156. Wiley-Interscience, New York, 1970. [2] Methoden der Organischen Chemie (Houben-Weyl) (ed. H. Kropf), 4th edn, Vol. 4/la. Thieme, Stuttgart, 1981. [3] Methoden der Organischen Chemie (Houben-Weyl) (ed. E. Muller), 4th edn, Vol. 4/lb. Thieme, Stuttgart, 1975. [4] Methoden der Organischen Chemie (Houben-Weyl) (ed. J. Falbe), 4th edn, Vol. E5. Thieme, Stuttgart, 1985 (see especially pp. 209-215). [5] Methoden der Organischen Chemie (Houben-Weyl) (ed. E. Muller), 4th edn, Vol. 8. Thieme, Stuttgart, 1952 (see especially pp. 407-418, 557-560). [6] M. A. Ogliaruso and J. F. Wolfe, in The Chemistry of Functional Groups. The Chemistry of Acid Derivatives (ed. S. Patai), Part 1, pp. 267-490. Wiley-Interscience, New York, 1979. 6.1. Oxidation of Aldehydes Apart from the general references listed in the preceding section, information specifically on the oxidation of aldehydes is available in certain texts [1-6]. In the present book, within the subject area of aldehyde oxidation, the conversion of aldehydes or their simple derivatives to carboxylic acids or carboxylic acid derivatives is considered (Scheme l(a)-l(e)). 241 242 6. OXIDATION OF C A R B O N Y L COMPOUNDS RCHO * RC0 2 H (a) R'CHO * R 1 C0 2 R 2 (b) RCH(OH)S0 3 Na > RC0 2 H (c) R 1 CH(SR 2 ) 2 > R a C0 2 H (d) [1] H.-G. Padeken, in Methoden der Organischen Chemie (Houben Weyl) (ed. J. Falbe), 4th edn, Vol.
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