3. Naming Alkanes and Conformations Flashcards
what is a condensed structure?
form that shows which atoms are beside each other
what is a chemical formula?
states the number of atoms of each element
what is a line drawing?
replaces nonessential atoms like carbon and hydrogen with lines
what is a wedge dash formula?
formula with three types of lines
straight lines going into the plane of the page
wedges coming out of the page
dashes going into the page
what are Newman Projections?
looks down the axis of a carbon
front carbon represented by three substituent groups meeting at the center
back carbon represented by a large circle with substituents attached
what are Fischer’s projections?
formula with
horizontal lines representing molecules coming out of the page
verticle lines representing molecules going into the page
what is pyranose?
a six-membered ring
what is furanose?
a five-membered ring
how do you draw the cyclisized version of a Fischer projection?
- draw the appropriate shape
- number the carbons starting from the right vertice
- draw in the CHO and CH2OH
-groups on the left point up
-groups on the right point down
what happens to the hydroxyl groups if you are drawing the alpha-cyclized version?
the hydroxyl group points down on carbon one
what happens to the hydroxyl groups if you are drawing the beta-cyclized version?
the hydroxyl group points up one carbon one
what are chair conformations?
formula that looks like a lawn chair
what are axial positions?
substituents that point straight up or down
what are equatorial positions
substituents that points in the plane of the ring
which position are bulky substituents placed in chair conformations and why?
equatorial position to minimize steric repulsions
when asked to draw a molecule in two different chair conformations what should you do?
draw a chair conformation with the substituents in the equatorial position and the other in the axial position
what are the general naming rules? (6)
- identify the longest carbon chain
- if present, assign stereochemistry, R/S or E/Z
- identify the name of the functional groups
- identify which carbon number the functional groups are on
- add functional groups to the prefix of the name
- change the suffix if necessary
how are the names of substituent groups written in the molecule name? (3)
in alphabetical order
before the root name
lowest possible numbering
what is between the number and letters in the molecule name?
hyphens
