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5 bonding patterns in which resonance occurs
- Allylic lone pairs
- Allylic positive charge
- Lone pair of electrons adjacent to a positive charge
- A pi bond between two atoms with differenct electronegativities
- Conjugated pi ponds in a ring
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Vinylic position
directly bonded to a C=C double bond
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Allylic position
Bonded one atom away from a C=C double bond
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Delocalization
A very stabilizing force in which electrons are in resonance
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Bronsted-Lowry definition of acid/base reactions
- Acids donate a proton
- Bases accept a proton
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Reduction reaction
Results in a net increase in the number of C-H bonds, or a net decrease in the number of C-O bonds or equivalent
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Oxidation reaction
Results in a net decrease in number of C-H bonds or a net increase in the number of C-O bonds or equivalent
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What leads to a carboxylic acid?
Addition of a molecule of water to the aldehyde followed by a second oxidation
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Homolytic bond cleavage
Both atoms break equally and leave with the same number of electrons
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Heterolytic bond cleavage
One atom breaks off with a larger portion of electrons creating ions of both atoms.
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A (-) sign for ΔG tells us...
A process is product favored (spontaneous)
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A lower Energy of Activation results in...
A greater reaction rate
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Where do transition states occur?
An an energy maxima. (peaks on a graph)
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Where do intermediates occur?
At an energy minima. (low points between peaks)
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A catalyst can provide a more favorable pathway for an organic reaction by...
- Increasing the susceptibility of an electrophile to nucleophilic attack
- Increasing the reactivity of a nucleophile
- Increasing the leaving ability of a group by converting it to a weaker base
- Increasing the stability of a transition state
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What is the order of operations in a Mass Spectrometer?
- Sample introduction
- Ionization
- Mass Analysis
- Ion detection/data analysis
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ESI
Electrospray ionization: takes sample, mixes with a liquid, and sprays solution (which is highly charged) causing the molecules to fragment until its a 1+ charge
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EI
Electron Impact: putting a molecule in front of a filliment and shooting electrons at it in an attempt to change its charge
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MALDI
Matrix assisted laser disorption ionization: shoots powerful laser at sample which is partially protected by the matrix which absorbs some of the energy. This changes the charge of the molecule
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Ion separation (analyzer)
Quadruple mass spectrometer design. Shoots ions through a tube and allows them to be analyzed. Ions cannot touch sides of tube.
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Nominal molecular mass
the molecular mass to the nearest whole number
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The peak with the largest m/z value represents...
the molecular ion (M)
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What are fragment ion peaks?
Peaks with smaller m/z values, represent positively charged fragments of the molecule
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The more stable a fragment...
The more that will be observed in the mass spectrum
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Fragmentation behavior of Alkyl, Halides, Ethers, and Alcohols
- A bond between carbon and a more electronegative atom breaks heterolytically
- A bond between carbon and an atom of similar electronegativity breaks homolytically
- The bonds most likely to break are the weakest bonds and those that lead to formation of the most stable cation
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What kind of frequencies, wavenumbers, and wavelengths are associated with high energy?
- High frequencies
- Large wavenumbers
- Short wavelengths
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Types of bending vibrations in IR
- Scissor: inward towards central atom
- Rock: two branched atoms are pulled in one direction
- Twist: two branched atoms twist in opposite directions
- Wag: two branched atoms twist in same direction
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When a bond stretches...
The increasing distance between atoms increases the dipole moment
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