- Functional Groups - Halogens, Alcohols & Ethers

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 kind of functional groups are there? Check out Table R in your Reference Table.

TABLE R – Functional Groups -Halides -Alcohols -Ethers

Organic Halides One or more of the hydrogen atoms in an alkane is replaced with a halogen –F, Cl, Br, or I NotNot hydrocarbons! Often called halocarbons.

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.

Properties of Alkyl Halides  Alkyl halides due to there high molecular wt. have considerably higher B.P. than their corresponding alkanes  Bonds are polar but compounds are not soluble in water  Probably because they can’t form H bonds Is CHCl 3 a polar compound? What about CCl 4 ? Yes No PropaneChloropropaneBromopropane B.P. (deg. C) Density (g/ml)(Gas)

Naming Organic Halides Use prefixes to specify substituent: – fluoro, chloro, bromo, iodo If more than one, use di, tri, etc. to specify # of substituents. If necessary, give locations by numbering C-atoms in backbone so that the halide has the lowest number. c-c-c-c-c Br Br 2,3-dibromopentane

Naming Halides CH 3 Cl CH 3 CHFCH 3 H H–C–Cl H Chloromethane H H H H–C–C–C–H H F H C3H7FC3H7F 2-fluoropropane “Chloroform”

Name the following Compound: CH 3 CCl 2 CHClCH 3 Cl H Cl H H C – C – C – C H – C – C – C – C – H Cl Cl H trichlorobutane 2,2,3-trichlorobutane C 4 H 7 Cl 3

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”

Alcohols Alcohols contain the polar -OH functional group –OH groups are capable of Hydrogen bonding 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

Hydroxyl groups Alcohols can hydrogen bond because they have a Hydrogen atom that is bonded to oxygen. CH 3 –CH 2 –O-H This results in Much higher B.P.’s And higher water solubulity H-O-H

Physical properties of Alcohols NameFormulaB.P. (C)Sol. (g/100g H 2 0) MethanolCH 3 OH64.5Fully miscible EthanolCH 3 CH 2 OH78.3Fully miscible PropanolCH 3 (CH 2 ) 2 OH97Fully miscible ButanolCH 3 (CH 2 ) 3 OH1187.9

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

Types of Alcohols Alcohols are also considered to be either - primary, secondary, or tertiary alcohols Designations correspond to which carbon atom the –OH group is bonded to - Affects Chemical Reactivity/Properties - Tertiary more reactive than Primary Primary alcohol:OH bonded to –CH 2 0H Secondary alcohol:OH bonded to –CHOH Tertiary alcohol:OH bonded to -COH

Types of Alcohols Primary alcohol Secondary Alcohol Tertiary Alcohol

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

Ether’s Properties BP’s tend to be low Comparable to similar MW hydrocarbons No internal H-bonding 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/ml) Na 8

Naming Ethers (common names) Name the groups (alkyl) on either side and add ether to the end. List attached alkyl groups in order of increasing size If they are the same the side chain is labeled “Di” NO NUMBERS NEEDED to designate location of Oxygen!

Naming Ethers Name this compound: Dimethyl ether Ethylpropyl ether