Chemistry discussion response | Chemistry homework help
1
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Structure Influences Acidity and Basicity
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1. In one or two sentences or with an illustration, discuss how each of the
four factors below play a role in determining relative acidity strength. In
other words, discuss the general trends, be concise and specific.
a. Periodic Trends
b. Resonance
c. Induction
d. Orbitals
1.acidic strenth increases more down the group
compared to the left / right movement in a period.
A bond polarity will determine the relative acidity
strength in binary acids through a period. the
increase of electronegativity in the atom, the
higher the bond polarity / stronger the acid. The
size of the atoms increases down the groups as
well as the bond strenth.
2. resonance can increase the
overall strtenth on a acid.
3. induction the inductive effect. the
inductive effect increases as the
elctronegavity does. the group
inductive effect decreases down the
group. going down on the group
inductive effect decreases while the
acidty increases. the inductive
increases the electron density and
the acid weakens while as the
negative effect will decreases
electron density.
4. orbitals the sp orbital is the
highest electrongetivity and sp3 is
the least. the speherical shape of s
orbital demonstrates the force of
attraction from the nucleues. the
electrons are more tightly bound as
the increasement of electrongetivity.
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2. Analyze the two compounds below. Circle the structure which is most
acidic overall. Discuss the factors that led you to this choice.
3. Analyze the structure below. Circle the nitrogen atom which is considered
to be overall most basic. Provide a brief discussion to explain why this
nitrogen is considered to be most basic (hint: think about the orbital each
nitrogen lone-pair occupies). Draw relevant resonance structures of the
conjugate acid expected to form when this structure is treated with 1
equivalent of HCl. Underline the resonance structure(s) that have filled
octets everywhere.
Discussion:
Discussion:
the stablization of the carboxylate anion
is caused from the increasement of
acidity from negative inductive effects.
the distance of the COOH group
decreases with the effect of the
inductive effect. the carboylate anion is
stablized from the withdrawing of group
F at alpha position.
basicity depends on the
avalibility of the
electrons for lone pair
donation. this nitrogen
has a lone pair in the p
orbital without any.
paarticipation in the
conjugation. the
conjugate acid is
stablized by two
nitrogen atoms.
3
4. The pKa of the most acidic CH2 group in each of the following compounds
was measured in DMSO as solvent (reference: J. Org. Chem. 1981, 46,
4327–4331.)
Given the pKa data above, propose an explanation why compound 1 is more
acidic than compound 3.
Draw the conjugate acid formed and its other relevant resonance structures
Text
the H+ concernatrion is less in cmopound 3 than compound 1. tess kpa has more ka
volume.
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Given the pKa data above, propose which of the following two compounds
below (5 or 6) is more acidic by comparing the stability of the corresponding
conjugate bases. Include (ie. draw) all relevant resonance contributors in your
discussion. Do any resonance structures have greater contribution than others
to the overall stability? Underline the resonance structure that is considered
to be most stable overall.
compound 6 is more acidic the weaker conjugate base is more acidic. the lower the pKa has
the stronger acid. the charge is spread out over a less electronegative carbon in compound
5 this results in less stabilzation. compound 6 spread the charge over the electrongative
oxygen. this causes a more stab.e base and a more acidic compound.
