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53 Cards in this Set
- Front
- Back
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What is an isomer |
Same molecular formula with different structures (either atomic connectivity or spatial orientation) |
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What are structural isomers |
Constitutional isomers Only have same molecular formula but different connectivity |
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What are geometric isomers |
Cis-trans isomers |
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What is cis? |
Substituents on same side of double bond |
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What are trans |
Substituents are on opposite side of double bond |
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How do you determine the highest priority? |
1) Higher atomic weight for the first atom 2) Then go to the next atom --> 2nd atom with the higher atomic weight 3) Double bond takes priority over single bond but higher atomic weight takes priority over double bond |
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Is "cis" Z or E? |
Z |
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Is "trans" Z or E? |
E |
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What does chiral mean? |
Molecule not superimposible on mirror image |
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What does achiral mean? |
Superimposible mirror image |
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How can carbon atoms be chiral |
If they have four different substituents (asymmetrical) |
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On fischer projections is the horizontal lines wedges or dashes? |
Wedges |
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On fischer projections are the vertical lines wedges or dashes? |
Dashes |
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What does configuration mean |
Spatial arrangment of atoms or funcitonal group of a stereoisomer |
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What is relative configuration |
Configuration in relation to another chiral molecule |
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What is absolute configuration |
Spatial arrangement of atoms or groups within molecules relative to each other (R/S) |
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Is S going clockwise or counterclockwise |
Counterwise |
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Is R going clockwise or counterclockwise |
Clockwise |
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How do you decide if something is R or S? |
Assign priority groups Draw a circle from 1 --> 2 -->3 If 4 is into the page then it is orientated correctly if 4 is out of the page then is orientated opposite |
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What has optical acitivity |
Pairs of enantiomers (opposite R/S designation) |
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What does optical acivity mean? |
Can rotate plane polarized light |
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Will enantiomers rotate the light in the same or opposite directions |
Opposite |
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If you rotate light to the right is that D or L |
D |
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If you rotate light to the right is that positive or negative |
+ |
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If you rotate light to the left is that D or L |
L |
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If you rotate light to the left is that + or -? |
- |
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How do you calcualte specific rotation |
Observed rotation/ Concentration (g/ml) * length (dm) |
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What is a racemic mixture? Does it have optical activity? |
Equal concentration of + and - so no optical activity |
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n chiral centers hve ____ stereoisomers |
2^n |
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What is an epimers? |
Diastereomer that only differs at one carbon center |
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What is a meso compound |
Multiple chiral centers with an internal plane of symmetry. |
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Is a meso compound optically active? |
No |
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What is a conformational isomer |
Differ by rotation about 1 or more single bond can be seen using Newman projections |
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Practice drawing Newman Projections |
x |
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What does a staggered anti newman's projection look like |
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What does a gauche newman's projection look like? |
60 degrees |
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What does an eclipsed newman's projection look like? |
120 degrees |
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What does a totally eclipsed newman projection look like? |
0 degrees |
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What are the potential energy graph for all of the newman projections? |
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Will very low temperature slow or increase conformational interconversion |
Slow |
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If you don't have enough energy to overcome barrier will the interconversion even rotate |
No |
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What are the types of ring strain? |
*angle strain *Torsional strain *Non bonding strain |
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What is angle strain? |
Bond angles deviate from ideal values |
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What is torsional strain? |
Resistance to bond twisting Such as having the substitutents eclipsed |
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What is non bonded strain? |
Atoms or groups compete for space |
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What sort of orientation does the cyclobutane develop |
Puckered |
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What sort of orientation does the cyclopentane have
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Envelope |
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What sort of orientation does cyclohexane have? |
*Boat *Chair *Twist boat |
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What is the most stable cyclohexane conformation? |
Chair |
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What is the lest stable cyclohexane conformation |
Boat All atoms are eclipsed |
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What is the middle stable cyclohexane conformation |
Twist boat (Staggered gauche) |
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How can interconservion between two chair conformaiton be stopped |
With bulky group attached |
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Is equatorial or axial favored |
Equatorial Because axial has steric repulsion |
