Dẫn xuất halogen hóa hydrocarbon và các dẫn xuất halogen hydrocacbon thơm Giới thiệu Halogen là các yếu tố liên quan đến clo (Cl), brom (Br), flo (F), và i-ốt (I). Họ có thể tồn tại dưới dạng khí (Cl2, F2), một chất lỏng (Br2), hoặc rắn (I2). Phần chìm, còn được gọi là organohalogens, là một nhóm các hợp chất hữu cơ của cấu trúc đa dạng mà một trong các halogen đã được đính kèm. Các cấu trúc cốt lõi có thể là đơn giản, bao gồm một hoặc hai nguyên tử cacbon, hoặc phức tạp hơn và thơm (các. | chapter five Halogenated hydrocarbons and halogenated aromatic hydrocarbons Introduction Halogens are the related elements chlorine Cl bromine Br fluorine F and iodine I . They may exist as gases Cl2 F2 a liquid Br2 or a solid I2 . Halogenated hydrocarbons also known as organohalogens are a group of organic compounds of diverse structure to which one of these halogens has been attached. The core structure may be either simple consisting of one or two carbons or more complex and aromatic halogenated aromatic hydrocarbons or HAHs . Because they have been implicated almost universally in toxic reactions in mammals and lower species including carcinogenesis in some it is appropriate to consider them as a group despite their chemical diversity. Polycyclic aromatic hydrocarbons PAHs are multiringed planar chemicals that share many of the same toxicological properties as HAHs. Early examples of toxicity from halogenated hydrocarbons One of the oldest and simplest of these compounds is carbon tetrachloride CCl4 which was used extensively as a solvent and a dry-cleaning agent until its hepatotoxic nature was discovered. In fact it was used originally as a treatment for hookworm in humans and domestic animals and as a component in fire extinguishers. These uses may still exist in some parts of the world. CCl4 owes its toxicity to the fact that it is converted in the liver to carbon trichloride CCl3 which is a free radical capable of inducing peroxidation of lipid double bonds and poisoning protein-synthesizing enzymes. Older halogenated hydrocarbons include trichloroethylene and the anesthetics halothane and chloroform now abandoned because of its toxicity . Figure 21 shows the variety of structural formulae included in this class of compounds. The earliest form of poisoning associated with a halogen was probably bromism a condition resulting from the use or abuse of 2001 CRC Press LLC PBBs PCBs X BrorH X Cl orH 210 possible structures for each Figure 21 Structural formulae
