1 - Functional Groups - Halogens, Alcohols & Ethers Mr. ShieldsRegents Chemistry U17 L01

2 Functional Groups Besides hydrogen or carbon bonded to carbon Many other atoms can bond to carbon and these Lead to the formation of what are called “Functional groups” Each Functional group has it’s own unique chemical And physical properties So what are these different fuctional groups? Let’s take a look.

3 Check out Table R in your Reference Table. We’ll take a look at all of these Groups in time But right now we’re going to focus on… -Halides -Alcohols -Ethers

4 Organic Halides These compounds areThese compounds are often called halocarbons or the Halides One or more hydrogen atoms in an alkane is replaced with a halogen –F, Cl, Br, or I

5 Properties of Alkyl Halides  Alkyl halides are extremely unreactive -Often used when chemical inertness is important -Examples: CFC’s (refrigerants, Aerosol propellants, Teflon (polymer), Brominated compounds (Fire retardant clothing) - many of these compounds are now banned from use for health and environmental reasons.

6 Properties of Alkyl Halides  Alkyl halides due to there high molecular wt. & stronger IMF have considerably higher B.P. and greater density than their corresponding alkanes PropaneChloropropaneBromopropane B.P. (deg. C) Density (g/ml)(Gas)

7 Naming Organic Halides Use these prefixes to specify the substituent: – fluoro, chloro, bromo, iodo – Name substituents in alphabetical order If necessary, give locations by numbering C-atoms in longest backbone so that the halide has the lowest # –K–Keep halide alphbetical order. If more than one, use di, tri, etc. to specify # of substituents. c-c-c-c-c Br Br 2,3-dibromopentane Not 3,4-dibromopentane

8 Naming Halides CH 3 Cl CH 3 CHFCHBr 2 H H–C–Cl H Chloromethane H H Br H–C–C–C–Br H F H C 3 H 5 Br 2 F 1,1-dibromo-2-fluoropropane “Chloroform”

9 Name this compound: 3-Bromo-2-Iodopentane Name this compound: F Cl H-C C-H F Cl 1,1-dicloro-2,2-difluoroethane One of the “freons”

10 Alcohols Alcohols contain the polar -OH functional group –OH groups are capable of Hydrogen bonding –The –OH group is sometimes referred to as a Hydroxyl group This polar functional group affects physical properties –B.P is much higher than the corresponding Alkane Ethanol (C 2 H 5 OH) +78C // Ethane (C 2 H 6 ) -89C –Low Mol. Wt. Alcohols are very soluble in water –Ethanol is totally miscible in water, Hexanol sol. is 0.59g/100 ml

11 Hydroxyl groups Alcohols can hydrogen bond because they have a Hydrogen atom that is bonded to oxygen. This results in Much higher B.P.’s And higher water solubulity CH 3 –CH 2 –O-H H-O-H Remember… Alcohols are neither acids nor bases (they do not ionize in water to either H + or OH - )

12 Types of Alcohols An –OH attached to a terminal Carbon atom (-CH2-OH) is called a primary alcohol An –OH attached to an internal carbon with a hydrogen atom also attached to that carbon (-CHOH-) is called a secondary alcohol An –OH attached to an internal carbon that is attached to 3 other carbons is called a tertiary alcohol Ethanol (primary) 2-propanol (secondary)

13 Naming Alcohols Select as the parent structure the longest continuous carbon chain that contains the –OH Drop the –e from the alkane name of the carbon chain and add –ol Indicate by a number (if necessary) the position of the –OH group ethanol 2-propanol

14 Diols Diols, like dienes have 2 functional groups There are Two –OH groups (dihydroxy) Instead of ending in “ol” the name ends in “diol” Example on left – 2,2 - propanediol

15 Triols There are three –OH groups - Add suffix –triol to name Glycerine (common name) is actually a “Triol” 1,2,3 –propanetriol (Glycerol) OH OH OH H 2 C—- CH —CH 2 Known also as Tri-hydroxy alcohols

16 Ethers Even though ethers have an oxygen atom in their structure They are unable to form hydrogen bonds with themselves - alkyl groups are bonded directly to Oxygen - No hydrogen directly bonded to Oxygen Ethers are not linear, They have a bent shape similar to water

17 Ether’s Properties BP’s tend to be low Comparable to similar MW hydrocarbons No H-bonding possible ether to ether Solubility in water is reasonably high for lower M.W. ethers H-Bonding to Water is possible PropaneDimethyletherDiethylether M.W B.P. (deg. C) Sol in Water (g/100 ml) 8

18 Naming Ethers (common names) Name the alkyl groups on either side and add ether to the end. List attached alkyl groups in alphabetical order –If the alkyl group is the same the alkyl group is prefaced by “Di” followed by “ether”. (Ex. Diethyl ether) NO NUMBERS NEEDED to designate location of Oxygen! Ethylmethyl ether

19 Naming Ethers Name this compound: Dimethyl ether Ethylpropyl ether Notice that Table R lists This name incorrectly