tailieunhanh - TOXICOLOGICAL CHEMISTRY AND BIOCHEMISTRY - CHAPTER 13

Chương 13 hợp chất hữu cơ độc hại và Hydrocarbons GIỚI THIỆU 13,1 Các nguyên tắc cơ bản của hóa học hữu cơ được xem xét trong chương 1. Các chương hiện nay là đầu tiên trong bảy để thảo luận về thành phần hóa học độc tính của các hợp chất hữu cơ chủ yếu có nguồn gốc tổng hợp. Do phần lớn trong số hàng triệu hợp chất hóa học được biết đến nhiều hữu cơ - hầu hết trong số họ độc hại đối với một mức độ nhiều hay ít - hóa học độc tính của các. | Chapter 13 Toxic Organic Compounds and Hydrocarbons introduction The fundamentals of organic chemistry are reviewed in Chapter 1. The present chapter is the first of seven that discuss the toxicological chemistry of organic compounds that are largely of synthetic origin. Since the vast majority of the several million known chemical compounds are organic most of them toxic to a greater or lesser degree the toxicological chemistry of organic compounds covers an enormous area. Specifically this chapter discusses hydrocarbons which are organic compounds composed only of carbon and hydrogen and are in a sense the simplest of the organic compounds. Hydrocarbons occur naturally in petroleum natural gas and tar sands and they can be produced by pyrolysis of coal and oil shale or by chemical synthesis from H2 and CO. classification of hydrocarbons For purposes of discussion of hydrocarbon toxicities in this chapter hydrocarbons will be grouped into the five categories 1 alkanes 2 unsaturated nonaromatic hydrocarbons 3 aromatic hydrocarbons understood to have only one or two linked aromatic rings in their structures 4 polycyclic aromatic hydrocarbons with multiple rings and 5 mixed hydrocarbons containing combinations of two or more of the preceding types. These classifications are summarized in Figure . Alkanes Alkanes also called paraffins or aliphatic hydrocarbons are hydrocarbons in which the C atoms are joined by single covalent bonds sigma bonds consisting of two shared electrons see Section . As shown by the examples in Figure and Section alkanes may exist as straight chains or branched chains. They may also exist as cyclic structures for example as in cyclohexane C6H12 . Each cyclohexane molecule consists of six carbon atoms each with two H atoms attached in a ring. The general molecular formula for straight- and branched-chain alkanes is CnH2n 2 and that of a cyclic alkane is CnH2n. The names of alkanes having from one to ten carbon