week 1 Flashcards
isomers, functional groups, some reactions, naming isomers general definitions (54 cards)
types of Hydrocarbons and its hybridiastion
SATURATED-> sp3 carons for 4 sigma bonds
UNSTAURATED-> If sp or sp2 hybridised they can from multiple C-C bonds
alkanes
saturated
n= 2n+2
More carbon = higher boiling point b/c more deisty because more dispersion forces (intermolecular ) coz of longer chains
Isomers
Def: identical molecular formula but different molecular structure
An isomer cannot concert to another isomer without breaking bonds
Steps to constitutional isomer naming
- identify longest chain (may not be obvious may have to turn a corner)
- Count form the end of the long chain which achieves the lowest number
- Name side group at the branching point based on “ naming #1 prefix but with -yl as a suffix
- Assemble the name in the following order.
a) Longest linear chain branching point number (i.e. 2);
b)-side group name and
c) name of longest linear chain.
Constitutional isomers
molecules are connected in different orders
Conformers are not isomers
Instead they are the same chemical structure but have bonds rotated to different 3D structures
Alkenes
general form
moleclar geo
bond angle
have the general formula CnH2n
Eg 2 carbon 4 hydrogen
molecular geometry of a double bond is trigonal
Sp 2 120* from the next
Alkynes
general form
moleclar geo
bond angle
have the general formula CnH2n-2
molecular geometry of a triple bond is linear
Eg 4 carbon 6 hydrogen
Naming steps of the alkene group
- First assign priority to the two groups attached to one end of the alkene
- Now consider the other end and do the same thing
- If the “higher” priority groups are on the same side of the alkene then this is called Zusammen (Z) (CIS). Eg h on same side others on same side
- If on opposite sides it is called entgegen (TRANS)
Zusammen is German for together. Entgegen (E) is German for opposite.
Naming steps of full alkene isomer
tep 1
Identify longest chain - name it but change -ane to ene
=pentane to Pentene
Step 2
Count from either end of the chain and so the first carbon of the alkene chain gets the lowest number
Step 3
Name any side groups based on naming #1, in this case methyl and assemble the name in the following order
b) branching point
c) Side group name and
d) Name of the longest linear chain with the number for the first carbon of alkene embebbed
Trans -4-methylpent-2-ene
Cycloalkenes
naming
Step 1
Cyclo- five membered (pent-) ring with an alkene (-ene)
Cyclopentene
Step 2
Number all carbons in the ring stating from either end of the alkene
The correct numbering gives the lowest number to the subsequent group
3-chlorocyclopentane
Conformational analysis
ALKANES vs alkenes
A molecule such as ethane has many conformations
Similar stabilities rapidly converting at room temperature
Static conformations can be drawn as Newman or sawhorse projections
ALKENES
Alkenes need to add a lot of energy for them to change conformation as the double bond cannot rotate
What does achiral mean?
A molecule that is superimposable on its mirror image
ADDTION RECTIONS TO ALKENES: why +what
Alkenes react to strong acids by addition
converts an alkene to a halogenated alkenes
Proton (H+) has not elections (empty s orbital) and reactions with electron rich meolues to gain elections
Proton is electrophilic
And alkene is nueophillic (something tht likes to donate e-)
What is an addition reaction?
A reaction in which one molecule combines with another to form a larger molecule with no other products
REMBER MARKINKOVS RULE: CAN HAVE DIFFERENT IMSOER PRODUCTS DEPENDING ON WHERE CL OR H GOES
-> double bond is most likly to break and so this would be the predominate product formed
What is an aldehyde?
An organic compound containing the group CHO, formed by the oxidation of alcohols ( partial primary?? ahcol ox)
What is an alkyl halide?
A group of chemical compounds derived from alkanes containing one or more halogens
What is an amide?
an organic compound containing the group —C(O)NH2, related to ammonia by replacing a hydrogen atom by an acyl group
What is an amine?
an organic compound derived from ammonia (NH3) by replacement of one or more hydrogen atoms by organic groups.
What is an arene?
aromatic hydrocarbons (most commonly based on benzene rings) such as benzene and methylbenzene.
What does chiral mean?
Describes an object that is not superimposable on its mirror image
What is a cis isomer?
A stereoisomer in which the two more electronegative groups lie on the same side of a reference plane (i.e. double bond)
What are cis-trans isomers?
Stereoisomers that differ in the positioning of two groups with respect to a reference plane (i.e. double bond)
