Physical Properties of Carbonyl Compounds

TABLE 16.1 Some Physical Properties of Carboi l Compounds  

TABLE 16.2 Some Spectral Properties of Carbonyl Compounds  

Note that conjugated carbonyl compounds are always found at lower frequency than their unconjugated relatives. For example, cyclohexanone appears at 1718 cm and 2-cyclohexenone at 1691 cm (Fig. 16.14).Thus there is reduced double-bond character in the C=0 group in conjugated molecules. The resonance formulation of 2-cyclohexenone clearly shows the partial single-bond character of the carbon-oxygen bond in these compounds. 

FIGURE 16.14 Conjugation reduces the double-bond character of a carbonyl group. The result is a shift of the IR stretching band to lower frequency. 

5b Nuclear Magnetic Resonance Spectroscopy The carbonyl group inductively withdraws electrons from the nearby positions, and this inductive effect results in a deshielding of adjacent hydrogens. The further away from the carbonyl group, the less effective the deshielding. This effect is well illustrated by 2-pentanone (Fig. 16.15). 

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The polarity of the carbonyl group is manifest in the physical properties of carbonyl compounds. Boiling points for the lower members of a series of aldehydes and ketones are 50-80° higher than for hydrocarbons of the same molecular weight this may be seen by comparing the data of Table 16-2 (physical... 

The acid properties of carboxylic acids have been discussed previously (Sections 1.18 and 7.10). Recall that carboxylic acids have values of approximately 3-5 (Appendix II see also Special Topics I in the Study Guide and Solutions Manual). The acid properties of dicarboxylic acids will be discussed in Section 17.21. The boiling points and other physical properties of carbonyl compounds are listed in Appendix I. Carbonyl compounds have the following relative boiling points ... 

In addition to its effect on reactivity, polarization of the C=0 bond influences the physical properties of carbonyl compounds. For example, carbonyl compounds boil at higher temperatures than hydrocarbons, but at lower temperatures than alcohols of comparable molecular weight. 

During occupational exposure, respiratory absorption of soluble and insoluble nickel compounds is the major route of entry, with gastrointestinal absorption secondary (WHO 1991). Inhalation exposure studies of nickel in humans and test animals show that nickel localizes in the lungs, with much lower levels in liver and kidneys (USPHS 1993). About half the inhaled nickel is deposited on bronchial mucosa and swept upward in mucous to be swallowed about 25% of the inhaled nickel is deposited in the pulmonary parenchyma (NAS 1975). The relative amount of inhaled nickel absorbed from the pulmonary tract is dependent on the chemical and physical properties of the nickel compound (USEPA 1986). Pulmonary absorption into the blood is greatest for nickel carbonyl vapor about half the inhaled amount is absorbed (USEPA 1980). Nickel in particulate matter is absorbed from the pulmonary tract to a lesser degree than nickel carbonyl however, smaller particles are absorbed more readily than larger ones (USEPA 1980). Large nickel particles (>2 pm in diameter) are deposited in the upper respiratory tract smaller particles tend to enter the lower respiratory tract. In humans, 35% of the inhaled nickel is absorbed into the blood from the respiratory tract the remainder is either swallowed or expectorated. Soluble nickel compounds... 

Organic constituents that may be found in ppb levels in WP/F smoke include methane, ethylene, carbonyl sulfide, acetylene, 1,4-dicyanobenzene, 1,3-dicyanobenzene, 1,2-dicyanobenzene, acetonitrile, and acrylonitrile (Tolle et al. 1988). Since white phosphorus contains boron, silicon, calcium, aluminum, iron, and arsenic in excess of 10 ppm as impurities (Berkowitz et al. 1981), WP/F smoke also contains these elements and possibly their oxidation products. The physical properties of a few major compounds that may be important for determining the fate of WP/F smoke in the environment are given in Table 3-3. 

Structure and Classification of Alcohols 425 10-3 Nomenclature of Alcohols and Phenols 427 10-4 Physical Properties of Alcohols 430 10-5 Commercially Important Alcohols 433 10-6 Acidity of Alcohols and Phenols 435 10-7 Synthesis of Alcohols Introduction and Review 438 Summary Previous Alcohol Syntheses 438 10-8 Organometallic Reagents for Alcohol Synthesis 440 10-9 Addition of Organometallic Reagents to Carbonyl Compounds 443... 

In Chapter 21 we continue the study of carbonyl compounds with a detailed look at aldehydes and ketones. We will first learn about the nomenclature, physical properties, and spectroscopic absorptions that characterize aldehydes and ketones. The remainder of Chapter 21 is devoted to nucleophilic addition reactions. Although we have already learned two examples of this reaction in Chapter 20, nucleophilic addition to aldehydes and ketones is a general reaction that occurs with many nucleophiles, forming a wide variety of products. 

Yamazaki, M. and S. Saito The effect of physical properties of cigarettes on the content of carbonyl compounds in the mainstream smoke Effect of moisture... 

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