or functional groups

Functional groups Functional groups are parts of molecules that result in characteristic features. Many functional groups exist, we will focus on about 4.

Organic compounds having functional groups Alcohols Carboxylic acids Amino acids carbohydrates

1. Alcohols a class of organic compounds with an –OH (hydroxyl ) functional group. thus R-OH is the formula (The symbol “R” is used to represent any carbon chains or rings).

Alcohols CH4O C2H6O condensed structural IUPAC common formula formula name name CH4O H – C – O – H H Methyl alcohol methanol H – C – C - O – H H C2H6O ethanol Ethyl alcohol

Alcohols C2H6O2 C3H8O3 condensed structural IUPAC common formula formula name name H H C2H6O2 Ethylene glycol H – C – C – H OH ethanediol H – C – C - C – H H OH C3H8O3 propanetriol glycerol

Naming alcohols For IUPAC: drop the -e ending of the parent alkane name; add the ending -ol. Ethane ethanol H – C – C - O – H H

Naming alcohols Alcohols containing 2, 3, and 4 of the -- OH groups are named diols, triols, and tetrols respectively. H – C – C - C – H H OH propanetriol

Naming alcohols Common names: name the alkyl group, then followed by the word alcohol. One carbon alcohol = methyl alcohol H – C – O – H H

Properties of alcohols Much like water, alcohols are capable of forming hydrogen bonding between molecules. This means they will boil at a higher temp. than alkanes with a comparable number of C atoms. Alcohols of up to 4 carbons are soluble in water in all proportions.

2. Carboxylic acids General formula: R-COOH - C – OH O Functional group: - COOH or (carboxyl group) General formula: R-COOH weak acids (ionize slightly)

Carboxylic acids Named by replacing the -e ending of the corresponding alkane name with -oic and followed by the word acid methanoic acid; ethanoic acid.

Carboxylic acids CH2O2 C2H4O2 condensed structural IUPAC common formula formula name name O methanoic acid Formic acid CH2O2 H - C – OH H – C -C – OH O H C2H4O2 Acetic acid Ethanoic acid

3. Amino acids Functional groups: - NH2 (amino) and O (carboxyl). - C – OH O (carboxyl).

Amino acids C2H5NO2 C3H7NO2 condensed structural common formula formula name H2N - C - C – OH O H glycine C2H5NO2 H2N - C - C – OH O H CH3 alanine C3H7NO2

4. Carbohydrates O The functional group is (carbonyl) - C – O or -C – H O (aldehyde).

Carbohydrates H – C = O H – C – O H H – C – OH C = O HO – C – H fructose Glucose, C6H12O6

Hydrophilic groups Hydrophilic means “water loving.” Hydrophilic groups are electrically polarized. This makes the substances including a hydrophilic group soluble in polar solvents like water. Examples: - OH, - COOH, - NH2

Hydrophobic groups Hydrophobic means “water hating.” Hydrophobic groups are not electrically polarized. Therefore, hydrophobic substances are not soluble in water but soluble in non-polar solvents like benzene. Examples: alkanes, ethylene, acetylene, CCl4, oils, and fats.

Hydrophilic and hydrophobic groups The common soap is the Na salt of stearic acid. Its formula is: CH3(CH2)16COONa. When it dissolves in water, it produces Na+ and CH3(CH2)16COO- ions. CH3(CH2)16 COO- Hydrophobic tail Hydrophilic head

Hydrophilic and hydrophobic groups oil oil Micelle Hydrophobic tails dissolve oil. Hydrophilic heads stay away from oil but attracted by water molecules. So, the oil is washed away by soap and water.

Micelle oil

References www.chalkbored.com/lessons/chemistry-12/functional-groups.ppt www.cottonchemistry.bizland.com/.../Chapter%2023%20Functional%20Groups.ppt http://www.hastings-on-hudson-firedept.org/F500/images/f500_micelle.jpg