Aldehydes and Ketones

Even more fun stuff!

The Carbonyl Group

Alds and Kets contain the carbonyl group-in carbohydrates, common in living things.

• Carbohydrates are called polyhydroxyaldehydes/polyhydroxyketones

• Naming alds and kets and diffs-see board– Include cyclic ketones– Weird ones

alds/kets to know

• Methanal-formaldehyde

• Ethanal-acetaldehyde

• Propanal-propionaldehyde

• Propanone-acetone-dimethyl ketone

• Butanone-methyl ethyl ketone (MEK)

• *know both names and structures!

Common aldehydes

• Formaldehyde-the most common aldehyde• A gas at room temp• very toxic, denatures proteins, is

immediately absorbed by the body• used to make plastics, adhesives (carpet)• Kills bacteria, sterilizes surgical instruments• Technically, not the exact stuff used in

embalming

Formalin

• This is a 37% aqueous solution of formaldehyde• Is a biological preservative, used in embalming• Formalin reacts with proteins so that decay is inhibited and tissue

becomes firmer• Funeral home story• http://www.youtube.com/watch?v=CBxu7fkhgt0 links for these 2 may not

work

• http://www.youtube.com/watch?v=vzhiKpmqvsA• Green burials http://videos.howstuffworks.com/planet-green/30105-g-

word-forever-fernwoods-green-burials-video.htm• Embalming school http://www.youtube.com/watch?

v=SGSQ903qSAo&feature=fvw

More alds

• Acetaldehyde-toxic, but not as toxic as formaldehyde-causes hangovers

• Paraldehyde– once used as a hypnotic agent-not used much today b/c stinky and

nasty tasting– Hypnosis videos

http://videos.howstuffworks.com/discovery/31646-conspiracy-test-recalling-abductions-with-hypnosis-video.htm

– http://videos.howstuffworks.com/sciencentral/2922-hypnotic-suggestion-video.htm

– Show this one below-hypnosis in dentistry– http://www.youtube.com/watch?v=it_UfJ2by4k

Common Ketones

• alpha-chloroacetophenone• Structure• Alpha stuff

• It’s a lachrymator-very stinky/irritating-is used in tear gas and Mace

• Marines in gas chamber• http://www.youtube.com/watch?v=9Z5E-

QiNZ7I&feature=related• http://www.youtube.com/watch?v=obL3RP-

pCBM&feature=related

Acetone

• good solvent, flammable, may cause cancer• infinitely soluble in HOH• Used to dry out wet lab glassware• produced in the body during metabolism of

lipids• Normally is metabolized, but not in

diabetics• acetone can be excreted in urine and breath

More diabetic stuff

• When ketones in your body build up-Ketosis

• If you have a very high level of ketones, you can go into a diabetic coma.

• a high level of ketones can hurt the kidneys.

Misc story-don’t write this

• People have passed out on the street during diabetic comas. Police find them, smell acetone on their breath and throw them in jail thinking they were drunk.

• Unfortunately, they sometimes die.

Progesterone-a girl ketone

• Norethynodrel-first oral contraceptive for women-mimics action of progesterone

• Progesterone-hormone that preps uterine wall to accept fertilized egg

• Depo Provera-injectable contraceptive works in 3 ways– prevents sperm from reaching egg– inhibits ovulation– makes uterine lining unfriendly to fertilized egg

• *why some religions are opposed to the pill

Testosterone-a boy ketone

• Primary male sex hormone

• Resp for 2ndy sex characteristics-what does that mean?

• Also anabolic steroid

• Girls have it also, but guys 40-60 x >

More alds/kets• Dihydroxyacetone-in tanning lotions• Retinal-form of Vitamin A-too much can cause birth

defects• other forms of vitamin A are retinol, retinoic acid• Capsaicin-gives red peppers their hotness-found in

pepper spray• RTX (resiniferatoxin)-nose & skin irritant, used in

sneezing powder• Both RTX and capsaicin have been used to treat bladder

hyperreflexia-a need to go even when the bladder is empty

Physical Props of Alds/Kets

• Low Bpts b/c they don’t form H bonds w/each other-have no HO-’s!

• They’re polar molecules b/c carbonyl group is polar-many are soluble in HOH

• Have strong distinctive odors

Prep of Aldehydes/Ketones

• 1st degree alcohols aldehydesCA’s (like vinegar)

• 2nd degree alcohols ketones

• aldehydes go on to oxidize into CA’s but Ketones don’t oxidize

• Aldehydes and kets can be changed back into alcohols by reduction (opp of oxidation)

• Aldehydesreduced intoprimary alcohols• Ketonesreduced intosecondary alcohols

Rxns of Alds/Kets

• Alds must be kept in air-tight containers or else they will oxidize– Ethanolacetaldehydeacetic acid (vinegar)

99% of Ketones don’t oxidize(alpha hydroxy ones do)

– **why is this significant??? B/c it allows us to have 2 common tests to tell them apart (alds from kets)

1. Benedict’s Test

• Add unknown to the B’s solution (blue b/c of Cu in the Cu SO4 it contains), heat & look for a color change

• Cu+2(blue) + 2 e-sCu0 (metallic, reddish-brown)• In the presence of an ald, the copper ion gains electrons-it

is reduced! Charge decreases (chem I?) • The aldehyde(sugar) is oxidized• A color change from blue red is positive for ald• Kets give a neg test, no color change• Pregnancy test story

2. Tollens Test

• This is how they used to make mirrors• Also called the silver mirror test• Tollens solution contains AgNO3

• unknown is added to the Tollens solution, heated, a silver precipitate is a positive test for an ald

• http://www.youtube.com/watch?v=hUX_cpFWNso&feature=fvw