Bonding in organic compounds

The elements that are commonly part of organic compounds are all located in the upper right corner of the periodic table. They are all nonmetals. The bonds between atoms of these elements are essentially covalent. (Some organic molecules may form ions nevertheless, the bonds within each organic ion are covalent. For example, the salt sodium acetate consists of sodium ions, Na+, and acetate ions, CaHsOa. Despite its charge, the bonds within the acetate ion are all covalent.) 

The covalent bonding in organic compounds can be described by means of the electron dot notation (Chap. 5). The carbon atoms has four electrons in its outermost shell  

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In order to complete its octet, each carbon atom must share a total of four electron pairs. The order of a bond is the number of electron pairs shared in that bond. The total number of shared pairs is called the total bond order of an atom. Thus, carbon must have a total bond order of 4 (except in CO). A single bond is a sharing of one pair of electrons a double bond, two and a triple bond, three. Therefore, in organic compounds, each carbon atom forms four single bonds, a double bond and two single bonds, a triple bond and a single bond, or two double bonds. As shown in the table below, each of these possibilities corresponds to a total bond order of 4. 

Number and Types of Bonds Total Bond Order 

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To accommodate the new material on acids and bases in Chapter 1, the orbital hybridization model of bonding in organic compounds has been rewritten and placed in Chapter 2. In keeping with its expanded role. Chapter 2 in now titled Hydrocar bon Frfflneworks. Alkanes. ... 

Organic chemists have found a way to draw complex molecular structures in a very simple way, by not showing the C and H atoms explicitly. A line structure represents a chain of carbon atoms by a zigzag line, where each short line indicates a bond and the end of each line represents a carbon atom. Atoms other than C and H are shown by their symbols. Double bonds are represented by a double line and triple bonds by a triple line. Because carbon almost always forms four bonds in organic compounds, there is no need to show the C—FI bonds explicitly. We just fill in the correct number of hydrogen atoms mentally compare the line structure of 2-chlorobutane, QT3C1TC1CF12C]T3 (3a), with its structural form (3b). Line... 

There remains one topic to be discussed in our survey of chemical bonding in organic compounds. For most compounds, all the molecules have the same structure, whether or not this structure can be satisfactorily represented by a Lewis formula. But for many other compounds there is a mixture of two or more structurally distinct compounds that are in rapid equilibrium. When this phenomenon, called tauto-merism, exists, there is a rapid shift back and forth among the molecules. In most cases, it is a proton that shifts from one atom of a molecule to another. 

This chapter mainly treats transition metal-catalyzed direct functionalization of carbon-hydrogen bonds in organic compounds. This methodology is emphasized by focusing on important functionalizations for synthetic use. The contents reviewed here are as follows (i) alkylation of C-H bonds, (ii) alkenylation of C-H bonds, (iii) arylation of C-H bonds, (iv) carbonylation of C-H bonds, (v) hydroxylation and the related reactions, and (vi) other reactions and applications. 

Analysis of Fats.—The iodine value of a fat or oil is a quantitative measure of the number of carbon-carbon double bonds which it contains. This number is the amount of iodine in grammes which combines chemically with 100 g. of the fat or oil. Nowadays the number of double bonds in organic compounds is usually determined with per-benzoic acid (cf. p. 111). 

Lowry, the holder of the new chair in physical chemistry at Cambridge University, spoke in Paris in March 1924 on aspects of the theory of valence, including the electronic theory of valence, and in December 1925 on optical methods of verifying structural chemistry and his own hypothesis of semipolar double bonds in organic compounds. The occasions were meetings of the Societe de Chimique de France and the Societe de Chimie Physique. 62... 

The idea that chemical bonds in organic compounds are partially polar and can be associated with alternating positive and negative charges, has a long tradition in organic chemistry. 

Uses Laboratory reagent for detecting double bonds in organic compounds oxidizer in rocket propellants monopropellant increase octane rating for diesel fuel. 

We have already noted that the great strength of the 7r-bonds in organic compounds should be regarded as a special attribute of the first-row elements [84AG(E)272 87JST1]. This is evidenced by a comparison between the energies of the C=X bonds (X = C,Si,Ge,Sn) and that of X=X (X = C,Si) (see Table XX). Thus, the 7r-bonds formed by the Si, Ge, and... 

Light-activated shift of double bonds in organic compounds can promote the reaction of oxygen with a molecule. Once oxygen has bonded to a fuel component, oxidized organic compounds such as alcohols, aldehydes, esters, ethers, and acids can form. These compounds can then continue to react with other fuel components to form color bodies, gums, and insoluble deposits. 

NUCLEOPHILE. An ion or molecule that donates a pair of electrons to an atomic nucleus to form a covalent bond. The nucTeus that accepts the electrons is called an electrophile. This occurs, for example, in the formation of acids and bases according to the Lewis concept, as well as in covalent bonding in organic compounds. 

OZONOLYSIS. (1) Oxidation of an organic material, i.e., tall oil, oleic acid, safflower oil, cyclic olefins, carbon treatment, peracetic acid production by means of ozone. (2) The use ol ozone as a tool in analytical chemistry to locate double bonds in organic compounds and a similar use in synthetic organic chemistry for preparing new compounds. Under proper conditions, ozone attaches itself at the double bond of an unsaturated compound to form an ozonide. Since many ozonides are explosive, it is customary to decompose them in solution and deal with the final product. See also Oxygen. 

This reaction is used to determine the presence and position of double bonds in organic compounds it has been much applied to the elucidation of the structure of members of the terpene series. 

Quickly recognize the common ways in which atoms are bonded in organic compounds. You should also recognize unusual bonding situations and be able to estimate the stability of molecules with such bonds. 

Covalent bonding, in which electrons are shared rather than transferred, is the most common type of bonding in organic compounds. Hydrogen, for example, needs a second electron to achieve the noble-gas configuration of helium. If two hydrogen atoms come together and form a bond, they share their two electrons, and each atom has two electrons in its valence shell. 

The kind of bond formed in these two reactions used to be called a dative covalent bond because both electrons in the bond were donated by the same atom. We no longer classify bonds in this way, but call them o bonds or it bonds as these are the fundamentally different types of bonds in organic compounds. Most new bonds are formed by donation of both electrons from one atom to another. 

All atoms form a certain number of bonds in organic compounds. This can be explained by the valency concept . 

The most common H-A bonds in organic compounds are C-H, N-H, and 0-H. Because acidity increases left-to-right across a row, the relative acidity of these bonds isC-Hatoms bonded to C atoms are usually less acidic than H atoms bonded to any heteroatom. 

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