Malen Bara CHEMISTRY   -   Organic Chemistry

In an electrophilic aromatic substitution reaction, which intermediate is formed?

In electrophilic aromatic substitution, the intermediate formed is a sigma complex (also known as an arenium ion or Wheland intermediate). This intermediate features a partially positive charge and a disrupted aromatic system, which is later restored upon deprotonation.
Malen Bara CHEMISTRY   -   Organic Chemistry

Which of the following compounds is not aromatic?

Benzene, pyridine, and naphthalene all obey Huckel's rule for aromaticity, possessing (4n+2) π-electrons and a planar structure. Cyclooctatetraene, however, does not adopt a planar conformation and does not have (4n+2) π-electrons, making it non-aromatic.
Malen Bara CHEMISTRY   -   Organic Chemistry

In proton NMR spectroscopy, what splitting pattern would you expect for the protons on the methylene group in ethyl acetate (CH3COOCH2CH3)?

The methylene group (CH2) in ethyl acetate is adjacent to a methyl group (CH3), which causes spin-spin coupling. The three protons of the methyl group split the signal of the two methylene protons into a quartet due to the n+1 rule (n=3).
Malen Bara CHEMISTRY   -   Organic Chemistry

What is the first step in the retrosynthetic analysis of 1-bromo-2-phenylethane?

Retrosynthetic analysis involves breaking down the target molecule into simpler precursor structures. For 1-bromo-2-phenylethane, identifying how the phenyl group is attached to the ethane chain is crucial for determining the precursor molecules. In this case, one might consider the synthesis from ethylbenzene or from styrene via bromination.
Malen Bara CHEMISTRY   -   Organic Chemistry

In which of the following reactions does the formation of a carbocation intermediate occur?

The SN1 reaction mechanism involves two steps. The first step is the dissociation of the leaving group, leading to the formation of a carbocation intermediate. This carbocation then reacts with a nucleophile in the second step.
Malen Bara CHEMISTRY   -   Organic Chemistry

Which of the following compounds is chiral?

2-Butanol has a carbon atom (the second carbon) attached to four different groups: a hydroxyl group (-OH), a methyl group (-CH3), an ethyl group (-CH2CH3), and a hydrogen atom. This makes it chiral, possessing non-superimposable mirror images (enantiomers).
Malen Bara CHEMISTRY   -   Organic Chemistry

Which of the following functional groups can act as both an acid and a base?

Amines contain a nitrogen atom with a lone pair of electrons, which allows them to act as a base by accepting a proton. They can also act as weak acids by donating a proton from the hydrogen atoms attached to the nitrogen, although this is less common compared to their basicity.
Malen Bara CHEMISTRY   -   Organic Chemistry

Which of the following statements about the bonding in ethyne (acetylene, C2H2) is correct?

In ethyne, each carbon atom is sp hybridized, forming a linear molecule with a bond angle of 180 degrees. The carbon atoms are connected by a triple bond consisting of one sigma bond and two pi bonds.
Fani Warraich CHEMISTRY   -   Biochemistry

Nucleotides also serve as carriers of activated intermediates in the synthesis of

Fani Warraich CHEMISTRY   -   Biochemistry

When DNA is heated, the temperature at which ________ of the helical structure is lost is defined as the melting temperature.


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