Shared Flashcard Set

Details

Organic chem
carbohydrates and nucleic acids (chapt. 23)
58
Chemistry
Undergraduate 3
05/03/2009

Additional Chemistry Flashcards

 


 

Cards

Term
simiple sugars.
Definition
C(H2O)
Term
carbohydrates include
Definition
polyhydroxyaldehydes, polyhydroxyketones, and compounds taht are easily hydrolyzed to them
Term
monosaccarides
Definition
cannot be hydrolyzed further
Term
Glucose
Definition
is a polyhydroxyaldehyde. are called aldoses
Term
fructose
Definition
is a polyhydroxyketone. and are called toses.
Term
The aldehyde carbon
Definition
is the most highly oxidized and numbered 1 in the IUPAC name. so it's always at the tope of the Fisher projection
Term
the Ketosies
Definition
the carbonyl group is usually the second carbon from the top.
Term
Fisher projection
Definition
horizontal bonds are projected out. Vertical bonds are projected away. The most oxidized carbon is always at the top.
Term
simple sugars (mono)
Definition
glucose, fructose. sweet taste
Term
disaccarides such as sucrose (table sugar)
Definition
are molecules of one glucose adn one fructose. sweet taste
Term
polysaccarides (such as starch)
Definition
can by hydrolized to 1000's of glucose.
Term
Classification on monosaccharides
Definition
3 criteria: whether the sugar contianes ketone or aldehyde group. 2. # of carbon atoms in the carbon chain. 3. stereochemical configuration o fthe asymmetric carbon atom farthest from teh carbonyl group.
Term
Classification on monosaccharides (cont.)
Definition
TRIOSE, TETROSE, PENTOSE, HEXOSE, HEPTOSE. example glucose (6 carbon aldehyde)=aldohexose. Fructose (six carbon ketone)=ketohexose.
Term
Natural sugars
Definition
have D rotation.- have the OH group of he bottom asymmetric carbon on the right
Term
Pg. 1101. Start with D(+)-glyceraldehyde
Definition
will make 14 other compounds by adding C to it.
Term
Erythrose and Threo
Definition
a diastereomer is erythro if its fischer projection shows similar groups on teh same side of the molecule. Threo= if similar groups are on opposite sides of the fischer projection. (pg. 1102)
Term
diastereomers
Definition
2R, 3S= 2S, 3R
or
2R, 3R=2S, 3S.
Term
erythor and threo (for dissymetric)
meso, d,l for symmetric molecules
(Pg. 1103)
Definition
generally used only with molecuels that do not have symmetric ends.
MESO is used and (d,l) indicated the diasteromer and tell whether or not it has an enantiomer.
Term
epimers
Definition
sugars that differ only by the stereochemistry at a single carbon. it is generally stated (if not stated it is assumer C2.
Term
cyclic hemiacetals
Definition
when an alcohol and aldehyde is on the same chain of a 5-6 carbon chain it forms a cyclic hemiacetal. the cyclic form is more stable than a chain.
Term
to do hemiacetal= know how to go from fisher projection to ring to chair conformation
Definition
turn fisher projection to the right (aldehyde #1 is pointed towards us when turned to the right), OH is as follows on fisher (up = up, down=down). rotate so that 6 and 5 switch places and then do hemiacetal (Haworth projection is flat). You will then write chair conformer format. C1 always connected to 2 oxygen (one within the ring and one as an OH group). C1 can be axial or equatorial. PG. 1105 example of glucose
Term
Hemiacetal
Definition
for D confirmation the rotation from fisher to haworth projection puts the terminal -CH2OH upwards.
Term
pyranose, furanose
Definition
pyranose= 6 membered rings
furanose= 5 membered rings= flat haworth projection
Term
anomers
Definition
the flipping of C1 OH group in cyclic hemiactetals (both 5 and 6 membered rings)
Term
down(axial) = alpha anomer
up (equatorial)= beta anomer
Definition
Term
mutarotaion
Definition
occurs because the two anomers interconvert in solution. when either of the pure anomers dissolves in water, its roation dragually changes to an intermediate roation that results from equilibrium concentrations of the anomers
Term
epimerization (by base catylized)
Definition
abstraction alpha protron (C2) Hydrogen causes OH to switch arrangement
Term
enediol rearrangement= makes ketone on C2 carbon
Definition
Removes the alapha proton, reprotonates oxygen to give enediol, deprotonates teh oxygen on C2, reprotonates on C1 to give the ketose (pg 1111-1112)
Term
using BASE with sugars gets alot of enediol and epimerization side reactions!!
Definition
unless using protective groups
Term
reduction of monosaccharides
Definition
turns cyclic rings back to chain and keeps reducing chain. reduces chain from aldehyde or ketone by getting rid of double bond and anding Hyrdogen. (H2, Ni for aldehydes) or (NaBH4 for ketones *makes epimers!)
Term
bromine water
Definition
is used to oxidize ALDEHYDES! it does not oxidize ketones and does not cause epimerization or rearrangement o fthe carbonyl group. it can be used to distinguish aldoses adn ketoses. the product is aldonic acid (liek gluconic acid)(ex: pag 1114, -CHO turns to -COOH)
Term
HNO3= oxidizer of aldehydes and terminal group -CH2OH
Definition
is a stonger oxidizer than Br2 and water. so it oxidizes both aldehyde and terminal group -CH2OH. produces aldaric acid (ex: glycaric acid) Turns -CHO and -CH2OH to (COOH and COOH)
Term
Tollens test (2 Ag(NH3)2 and -OH
Definition
does not distiguish between aldehyde or ketone. it is used to find if it is in ring form or chain form. Tollens will not react if it's in ring form. reaction gives off metallic silver.
Term
glycosides
Definition
are sugars in teh form of acetals. -osides. ex: glucoside. if it's a six memebered ring: glucopyranoside. five ring = ribofuranoside. C1 carbon -OCH3
Term
to form glycosides.
*remember from chain used -OH and acid cat.
Definition
us ROH and H+. it will replace C1 -OH with -OR group. will form both beta and alpha equally.
Term
aglycone
Definition
is the group bonded to the anomeric carbon (C1) of the glycoside.
Term
Ether
Definition
sugars have a lot of -OH groups. Use (CH3I and Ag2O excess) to replace all H of -OH group with CH3. ex: -OH is then converted to OCH3 (all of them in the ring).
Term
ester formation
Definition
Replaces all -OH group with -OC(R)=O group. Uses acetic ANHYDRIDE and pyridine (excess (CH3CO)2O. (it takes part of the anhydride and connects to -O.
Term
osazone (H2NNH-phenly)
Definition
substance will work on both aldehyde and ketone C1 and C2!. Does not effect below C2. so the effects on C1 and C1 is =NNH(PH).
Term
Chain shortening: Ruff degradation (aldehyde)
Definition
Starts by Bromine water (Br2, H20) to get aldonic acid then treats with hydrogen peroxide adn ferric sulfate. the result is -CHO as C1 and one C shorter than what it started out with. ex: page. 1120-1121
Term
Kiliani-Fischer synthesis (lengthens an aldose carbon chain.
Definition
Adds one carbon atom to the aldehyde end of the aldose. the former C1 is now C2. The end result is -CHO added. Materials used HCN/KCN --> H2/pd/BaSO4 --> H3O+
Term
clues that told Fischer the correct type of glucose (CLUE 1)
Definition
clue 1: on ruff degradation, glucose and mannose give the same aldopentose: D-(-)-arabinose. this suggests that glucose and mannose are C2 epimers (confirmed by treating with phenylhydrazine and showing it gives the same osazone.
Term
CLUE 2
Definition
on ruff degradation D-(-) arabinose give the aldotetrose D-(-) erythrose. upon treatment with nitric acid, erythrose gives an opticaly inactive aldaric acid (meso). this means D-erythrose, botained from ruff degradation of D-aldopentose, mut be a D-aldotetrose.
Term
CLUE 3
Definition
on oxidation with nitric acid D(-) arabinose gives an optically active aldaric acid. The means, of the two structures for D-arabinose, only the second would oxidize to giv an optically active aldaric acid. the other structure must be arabinose
Term
CLUE 4
Definition
when the -CHO and -CH2OH groups od D-mannose are interchanged, the product is still D-mannose. when the -CHO and -CH2OH groups of D-glucose are interchanged, the product is an unnatural L sugar. Meaning, if the two end groups of structure X are interchanged, the product looks strange. when we rotate 180 degrees it is the same.
Term
determination of ring size
Definition
must treat ring with CH3I (RI) and Ag2O in excess--> H+ (H3O). this breaks the O (in the ring) bond with C5. it gets it back into a strain chain form (pg. 1128)
Term
cleavage with HIO4, H+
Definition
Term
disaccarhides
Definition
can link at 1, 4' or 1, 6', or 1, 1'. all through O
Term
most common is 1, 4'
Definition
cellobiose(beta), maltose(alpha),lactose(beta).
Term
1, 6' : Gentiobiose
Definition
Term
sucrose
Definition
1, 1' linkage (one glucose and one fructose, 6 and 5 memebered rings.) sucrose does not reduce tollens reagent and it cannot mutarotate
Term
Maltose
Definition
alpha-1,4' link with two glucose units.
Term
Cellobiose
Definition
beta- 1, 4' link with 2 glucose units. C4 OH is in alpha position
Term
Lactose
Definition
beta 1, 4' linkage with 2 glucose. C4 OH group is in beta position
Term
Polysaccharieds
Definition
does not react with tollens reagent, and they do not mutarotate
Term
nucleic acid
Definition
backbone is ribofuranoside (five membered ring)linked by phosphate ester groups.
Term
RNA
Definition
two class: moncyclic (cytidine, uridine)(also pyrimidine)
bicyclic: adenine and guanine (also purine)
Term
AT, CG
Definition
Supporting users have an ad free experience!