Organic Chemistry Flashcards
What are aliphatic molecules?
Aliphatic molecules – any molecules (chains, rings, branched chain) that are not aromatic! Single, double and triple bonds are allowed.
What are aromatic molecules?
Aromatic molecules – any molecules that contain a particular type of resonance structure in rings. Benzene is the archetypal example (C6H6).
Where can alkanes be found?
alkanes are found in Viridiplantae waxes and resins of some Pinales plus oils of some Aves and Chondrichthyes.
Where can alkynes be found commonly?
alkynes are common in some Viridiplantae waxes and in some Anthozoa and Porifera.
What is an OH group and where is it found?
hydroxyl groups (-OH) found in alcohols
e.g. propan-1-ol, propan-2-ol
* found in all sugars, sugar alcohols.
What is a (C=O) group and where is it found?
A carbonyl groups (-C=O)
If on the end of a chain= aldehydes
e.g. butanal (aka butyraldehyde)
aldehydes are important metabolic
intermediates.
Aldehyde moieties are found in reducing
sugars.
If in the middle of a chain: ketones (names
end in –one)
e.g. butan-2-one (aka methyl ethyl ketone)
ketone moieties are found in many nonreducing sugars.
What is a (-COOH) group and where is it found?
carboxyl group (-COOH)
It forms carboxylic acids (-oic acid)
e.g. butanoic acid
If ionised (deprotonated) they form carboxylates (-oate) e.g. butanoate
* Found as fatty acids form part of every lipid.
Explain ester formation and give an example of an aroma.
A reaction of carboxylic acid with an alcohol forms an ester e.g.
C2H5OH + C4H9COOH → (C2H5)OCO(C4H9)
ethanol + pentanoic acid (valeric acid) → ethyl valerate
* aromas of many fruits and flowers are esters:
* ethyl acetate (European pears, Pyrus communis L.)
What are ethers and where are they found?
Ethers have a bridging oxygen (-O-) between two groups e.g. dimethyl ether (H3C-O-CH3)
ethers are found in double-headed lipids of some Archaea.
What are organic sulfides and what are they important for?
organic sulfides have a bridging sulfur (-S-) between two groups e.g. dimethylsulfide (H3C-S-CH3)
organic sulfides are important signalling molecules for Aves, marine Mammalia and in some flowers of the Archeae.
* organic disulfides (and trisulfides)and these are important in protein folding, also found in many Viridiplantae.
Aromatic rings and explain what occurs as a result of delocalised electrons
Archetype is the benzene ring (C6H6) but other
aromatic rings are also found e.g. C6H5
- groups are phenyl- groups/ benzyl-groups.
* C6H5CH2
Delocalised electrons must be present, this means alternating C-C and C=C bonds around the ring
that “flip” back and forth in resonance on a
femtosecond scale.
Application of aromatic versus aliphatic
Use of hydroxylated carboxylic acids
Use of Glycolic acid ( small and aliphatic)
Use of salicylic acid (benzene ring) or Mandelic acid (an aromatic)
Carboxylic acid used in skincare products, they can break bonds between dead skin cells and encourage shedding.
Glycolic acid (small and aliphatic), meaning it’s very water-soluble and is small enough to penetrate layers of dead skin,
but it won’t dissolve in sebum in pores so will only
shed surface skin – important for older or dryer skin.
Salicylic acid (benzene ring) meaning it’s fat-soluble and will dissolve in sebum in pores and shed dead cells from inside of pores –important if you have oily or combination skin.
Mandelic acid (an aromatic) is a good alternative to salicylic acid.
How to detect some optical isomerism
They can rotate plane polarised light an the direction of rotation is relative to that of a standard substance gives them a prefix of (D)- or (L)- from dextro (right) and laevo (left). This
cannot be determined from looking at a structure, only in vitro.
* all amino acids found within proteins are (L)-.
* most natural monosaccharides are (D)-.
What is a racemic mixture
a sample of a substance that contains both e.g. (D)-
lactic acid and (L)-lactic acid is written (D/L)-lactic acid
and is called racemic lactic acid (or lactic acid racemate).
What is a thiol group?
SH group- very smelly and used as a mixture with natural gas so we can detect leaks and its also a defense mechanism skunks use.
