Reaction between halogens and concentrated nitric acid I have read that the reaction between $\ce{I2}$ and conc. $\ce{HNO3}$ gives $\ce{HIO3}$ and $\ce{NO2},$ but there is no mention of the other halogens' products. Do they all give halous acids and nitrogen dioxide? Specifically with chlorine, how does the reaction proceed?
This question can easily be addressed considering reduction potential of each compound. Concentrated nitric acid is a powerful oxidizing acid, which has a high reduction potential:

$$
\begin{align}
\ce{NO3- + 4H+ + 3e- &amp;&lt;=&gt; NO + 2H2O} &amp;\quad E^\circ &amp;= \pu{0.957 V} \tag1\\
\ce{NO3- + 3H+ + 2e- &amp;&lt;=&gt; HNO2 + H2O} &amp;\quad E^\circ &amp;= \pu{0.934 V} \tag2\\
\ce{2NO3- + 4H+ + 2e- &amp;&lt;=&gt; N2O4 + 2H2O} &amp;\quad E^\circ &amp;= \pu{0.803 V} \tag3
\end{align}
$$

Now, let's look at reduction potential of halides:

$$
\begin{align}
\ce{F2 + 2e- &amp;&lt;=&gt; 2F-} &amp;\quad E^\circ &amp;= \pu{2.866 V} \tag4\\
\ce{Cl2 + 2e- &amp;&lt;=&gt; 2Cl-} &amp;\quad E^\circ &amp;= \pu{1.3583 V} \tag5\\
\ce{Br2 + 2e- &amp;&lt;=&gt; 2Br-} &amp;\quad E^\circ &amp;= \pu{1.066 V} \tag6\\
\ce{I2 + 2e- &amp;&lt;=&gt; 2I-} &amp;\quad E^\circ &amp;= \pu{0.5355 V} \tag7\\
\end{align}
$$
Accordingly, we can list oxidizing power at standard conditions in decreasing order:

$$\ce{F2} &gt; \ce{Cl2} &gt; \ce{Br2} &gt; \ce{NO3-} &gt; \ce{I2}$$

Therefore, at standard condition, concentrated $\ce{HNO3}$ acid (meaning $\ce{NO3-}$ in acidic medium) can easily oxidize only $\ce{I2}.$ One such example is documented in Ref.1. According to the authors, the oxidation of iodine by hyperazeotropic nitric acid ($\pu{16–21 M}$) was shown to proceed in at least two steps: 

$$
\begin{align}
\ce{I2 + 3HNO3 &amp;&lt;=&gt;[$k_1$][$k_2$] 2I+ + 2NO3- + 2HNO2 + H2O}\\
\ce{I+ + 6HNO3 &amp;&lt;=&gt;[$k_3$][$k_1$] I^5+ + 4NO3- + 2HNO2 + 2H2O}
\end{align}
$$

Since reduction potentials of $\ce{HNO3}$ and $\ce{Br2}$ are in such close range that each can oxidize the other. In fact, the kinetic studies of this phenomenon has been performed in literature (Ref.2).

In different aspect, there is a publication (Ref.3) claiming that the presence of bromine in fuming nitric acid makes it a brominating reagent (electrophilic aromatic substitution):



This bromination has worked well with deactivated aromatic nucleus. In absence of bromine, the reagent nitrate the ring. Thus, it is safe to suggest that $\ce{HNO3}$ might promote formation of '$\ce{Br+}$', meaning oxidation.

References:


J. C. Mailen, T. O. Tiffany, "The reaction of iodine with concentrated nitric acid," Journal of Inorganic and Nuclear Chemistry 1975, 37(1), 127-132 (https://doi.org/10.1016/0022-1902(75)80139-4).
Istvan Lengyel, Istvan Nagy, Gyorgy Bazsa, "Kinetic study of the autocatalytic nitric acid-bromide reaction and its reverse, the nitrous acid-bromine reaction," J. Phys. Chem. 1989, 93(7), 2801–2807 (https://doi.org/10.1021/j100344a021).
Alexander M. Andrievsky, Vera I. Lomzakova, Mikhail K. Grachev, Mikhail V. Gorelik, "Aromatic Bromination in Concentrated Nitric Acid," Open Journal of Synthesis Theory and Applications 2014, 3(2), Article ID:44941, 5 pages (doi: 10.4236/ojsta.2014.32003).