Organic Chemistry Functional Groups: - Aldehydes - Ketones - Organic Acids - Esters - Amines - Amides

Aldehydes Group is always on a terminal C – no need to specify location by number Condensed it is symbolized by a -CHO group at the end of the formula C = O is known as a carbonyl group Drives the physical and chemical properties of these compounds Aldehydes have characteristic scents and tastes Cinnamon is an example

Aldehydes Drop the –e from the end of the alkane and add –al; C=O is C #1 Name these two compounds: Methanal (formaldehyde) Butanal

Ketones Like the aldehydes the Functional group is the carbonyl group C=O Contains an alkyl group on either side of the C=O In aldehydes one side is an alkyl group the other is H Often used as a solvent Acetone is one example

Naming Ketones Number the C chain so C=O has the lowest # Drop the final e from the alkane name and add -one Name these compounds: 4-methyl-2-pentanone C-C-C-C-C C o 3-hexanone

Properties Both aldehydes & ketones have A carbonyl functional group. C=O is polar & their compounds Are polar. This leads to: Higher B.P’s than non-polar molecules Lower than alcohols that can H-bond w/ each other Can not H-bond between each other but can H-bond to solvents like water - Lower MW compounds are appreciably soluble in water Propanone Propanal

Properties Butane Diethyl ether Propanal Propanone 1-propanol M.W. 58 60 B.P (deg.C) 35 49 56 97 Solubility g/100g H2O Insol. 8 16 Fully miscible Fully miscible

Organic Acids Condensed form is written –COOH A carbonyl group and a hydroxyl group bonded to C Known as a carboxyl group A terminal functional group The carboxyl group is an organic acid. It is the H on the end of COOH that is donated as a proton (H+) What is left is the anion R-COO-

Carboxylic acids ionize in water to form a proton and A carboxylate anion

Naming Organic Acids The carboxyl group is a terminal group no need to give it a number. It’s always on C #1 Drop the –e from the alkane name and add –oic acid Name this compound: Butanoic acid

Naming Organic Acids Name this compound: Name this compound: Butanoic acid Name this compound: 2,4-dimethylhexanoic acid C-C-C-C-C-COOH C C

Some Common Carboxylic acids CH3C=O OH HC=O OH Ethanoic Acid “Acetic Acid” Methanoic acid “formic acid” The sting of ants Vinegar C-C-C-COOH Butanoic acid Rancid butter smell

Physical properties Sharp or noxious smells polar and can form 2 hydrogen bonds with themselves and with water C-C=O OH HO O=C- C C-C=O OH H O This leads to high B.P. and high solubility in water - 1st four acids are totally miscible in water

Comparison of properties Butane Diethyl ether Propanal Propanone 1-propanol ethanoic M.W. 58 60 B.P (deg.C) 35 49 56 97 118 Solubility g/100g H2O Insol. 8 16 Fully miscible Fully miscible

Esters Esters are derivatives of Carboxylic acids Combination of an Alcohol and an Acid The alcohol provides the alkyl portion of the ester name Esters are polar but can not form hydrogen bonds with one another BP’s of esters are lower than alcohols or acids with similar mass

Physical properties M.W. 72 74 B.P (deg.C) 76 80 57.5 118 141 Butanal Butanone Methyl ethanoate 1-butanol Propanoic Acid M.W. 72 74 B.P (deg.C) 76 80 57.5 118 141

Properties Esters have distinctive odors (flowers, flavors etc.) - Function of which alcohol is combined with which acid Alcohol Acid Ester Fragrance Ethanol Butanoic acid Ethyl butanoate Pineapple Pentanol Ethanoic acid Pentyl ethanoate Banana Octanol Octyl ethanoate Orange Methanol Salicylic acid Methyl salicylate wintergreen Methyl butanoate apple

Naming Esters Esters are not a terminal group but they are unique because of the carboxyl group therefore the carbonyl carbon is considered to be C #1 Name the group attached to the hydroxyl oxygen first (the alkyl group) Next name the carboxylate carbon chain, dropping the –e and adding –oate Written condensed format is RCOOR’

Name this compound: Ethyl butanoate Name this compound: O CH3-C-O-CH2-CH2-CH-CH3 CH3 3-methylbutyl ethanoate

What alcohols and acids produce the above esters? (Not IUPAC) 2-methylbutyl ethanoate What alcohols and acids produce the above esters?

(Not IUPAC)

Amide Like esters the amide functional group is a derivative of carboxylic acids OH replaced by the amine group The amide group is a terminal group Important biological molecules Links amino acids together to form proteins

Amide Physical Properties Amides have very high BP’s due to strong intermolecular hydrogen bonding - higher than similar esters and acids - H-bonding can occur between N, H and O CH3 – C=O NH2 CH3COOCH3 CH3COOH CH3COONH2 B.P. (deg. C) 57.5 118 221

Amide Take the name of the alkane with the same number of carbon atoms Drop the –e from the alkane name and add –amide Amide carbon is carbon #1 when naming side chaines Ethanamide

Name this compound: C-C-C=O C NH2 2-methylpropanamide

Amines Nitrogen is the functional part of an amine Nitrogen can form three bonds (just like NH3) One must be to the carbon chain The other two bonds can be to Carbon and/or H2 C-C-NH2 or Primary Amine C-C-N-H or C Secondary Amine C-C-N-C C Tertiary Amine

Physical properties of Amines Like ammonia, amines are polar compounds H can also be Carbon Based groups And like ammonia, amines are Bronsted-Lowery Bases - both are Proton acceptors H :N-H H+

Physical properties of Amines - Since amines can act as proton acceptors reaction With a proton donor like HCl will lead to a salt, i.e. an ionic compound H :N-H H :N-H HCl + Cl- H +

Physical Properties of Amines Amines can hydrogen bond like alcohols or Carboxylic acids - Contains N and H - H-bonding raises the B.P. but it is not as high as the alcohols or acids H C-C-N Ethanoic acid Ethanol Ethyl amine B.P. (deg C) 118 78 17 H N-C-C Tertiary amines have higher BP’s than secondary and secondary is higher than primary

Physical properties of Amines Amines can H-bond with water Leads to high water solubility up to about 6C Methyl Amine Ethyl Propyl Butyl Sol (g/100g H20) v. Sol Totally miscible Miscible v. sol Amines have very strong odors Methyl and ethyl amine smells like ammonia Higher MW amines often have a fishy smell Aromatic amines are generally toxic Readily absorbed through skin often with fatal results

Amines Need #’s to designate the location of the amine Name your carbon chain as an alkane, drop the –e and add –amine If there are 2 amines indicate their location and add –diamine to the alkane name 2-butanamine

Name this compound: C-C-C-C-C-C N N 1,3-hexadiamine

Amino Acids Related to amines are the Amino Acids If you have a “N” and a COOH it is an amino acid GLYCINE Since the amino group is a proton acceptor and the Carboxylic acid is a proton donor amino acids are Actually NH3+ and COO-.