Alcohol and Their Derivatives PDF

Alcohols, Ethers and Epoxides Organic chemistry Alcohols Structure and Bonding Alcohols contain a hydroxy group (OH) bonded to an sp3 hybridized carbon. They are classified according to the number of alkyl groups attached to carbon bearing the OH. Enols, Phenols and Ethers Compounds having a hydroxy...

Alcohols, Ethers and Epoxides Organic chemistry Alcohols Structure and Bonding Alcohols contain a hydroxy group (OH) bonded to an sp3 hybridized carbon. They are classified according to the number of alkyl groups attached to carbon bearing the OH. Enols, Phenols and Ethers Compounds having a hydroxy group on a sp2 hybridized carbon—enols and phenols—undergo different reactions than alcohols. Ethers have two alkyl groups bonded to an oxygen atom. Epoxides Epoxides are ethers having the oxygen atom in a threemembered ring. Epoxides are also called oxiranes. Epoxides The C-O-C bond angle for an epoxide must be 60°, a considerable deviation from the tetrahedral bond angle of 109.5°. Thus, epoxides have angle strain, making them more reactive than other ethers. Nucleophiles attack the electrophilic C of the C-O bond causing it to break, resulting in ring opening. Epoxides can react with a large range of nucleophiles. Naming Alcohols Naming Alcohols Oxygen Hybridization and Geometry The oxygen atom in alcohols, ethers, and epoxides is sp3 hybridized. Alcohols and ethers have a bent shape like that in H2O. The bond angle around the O atom in an alcohol or ether is similar to the tetrahedral bond angle of 109.5°. Because the O atom is much more electronegative than carbon or hydrogen, the C-O and O-H bonds are both polar. Naming Alcohols Naming Alcohols Attached to Rings When an OH group is bonded to a ring, the ring is numbered beginning with the OH group. Because the functional group is at C1, the 1 is usually omitted from the name. The ring is then numbered in a clockwise or counterclockwise fashion to give the next substituent the lowest number. Naming Alcohols Common Names of Alcohols Common names are often used for simple alcohols. To assign a common name: Name all the carbon atoms of the molecule as a single alkyl group. Add the word alcohol, separating the words with a space. Naming Alcohols Diols and Triols Compounds with two hydroxy groups are called diols or glycols. Compounds with three hydroxy groups are called triols. Naming Ethers Naming Ethers Simple ethers are usually assigned common names. To do so: Name both alkyl groups bonded to the oxygen, arrange these names alphabetically, and add the word ether. For symmetrical ethers, name the alkyl group and add the prefix “di-”. Naming Ethers Naming Complex Ethers More complex ethers are named using the IUPAC system: 1. Make the larger alkyl group as an alkane (the parent chain). 2. Name the smaller alkyl group as an alkoxy substituent by changing the -yl ending of the alkyl group to -oxy. 3. The alkoxy group as a substituent bonded to the parent chain. Naming Complex Ethers Naming Ethers Cyclic Ethers Cyclic ethers have an O atom in the ring. A common example is tetrahydrofuran (THF). Dioxane is heterocyclic organic compound. It is used as a solvent in the laboratory. Naming Epoxides Naming Epoxides Epoxides can be named in three different ways: epoxyalkanes, oxiranes, or alkene oxides. To name an epoxide as an epoxyalkane, first name the alkane chain or ring to which the O atom is attached, and use the prefix “epoxy” to name the epoxide as a substituent. Use two numbers to designate the location of the atoms to which the O is bonded. Naming Epoxides Naming Epoxides as Oxiranes Epoxides bonded to a chain of carbon atoms can also be named as derivatives of oxirane (root “ir” from “tri” for 3-membered; prefix “ox” for oxygen; “ane” for saturated). the simplest epoxide having two carbons and one oxygen atom in a ring. The oxirane ring is numbered to put the O atom at position one, and the first substituent at position two. No number is used for a substituent in a monosubstituted oxirane. Naming Epoxides Naming Epoxides Naming Epoxides as Alkene Oxides Epoxides are also named as alkene oxides, since they are often prepared by adding an O atom to an alkene. To name an epoxide in this way: Mentally replace the epoxide oxygen with a double bond. Name the alkene. Add the word oxide. Hydrogen Bonding in Alcohols Alcohols, ethers, and epoxides exhibit dipole-dipole interactions because they have a bent structure with two polar bonds. Alcohols are capable of intermolecular hydrogen bonding. Thus, alcohols are more polar than ethers and epoxides. Solubility in Water Physical Properties