芳烃的直接硝化是合成芳香族硝基化合物最重要的方法。可使芳烃硝化的试剂很多，最常用的是硝酸及其盐、以及硝酸酯、硝酸鎓盐、氧化氮类等。通常，硝化试剂的选择取决于硝化试剂及芳香族化合物的反应活性、硝化的区域选择性和一元硝化及多硝化的控制等因素。另外，重氮盐、硼酸被硝基取代，苯胺氧化，也能合成芳香族硝基化合物。近年来，过渡金属催化的芳烃硝基化反应，由于其环保，反应条件温和，也成为人们研究的一个热点。

HNO3 作为硝化试剂反应示例

硝酸是最常用的硝化试剂之一，它能使许多芳香族化合物发生硝化，普通硝酸和发烟硝酸都能用于硝化。

A wide-mouth 1-L flask is supported inside a water bath. The flask is fitted with a moderate-speed stainless-steel propeller-type stirrer, and nitric acid (sp. gr. 1.4, 350mL.) at 20 °C is poured into it. Veratraldehyde (70 g, 0.42 mole) is crushed at least as fine as rice grains and is slowly added in small portions to the acid. The rate of addition should be such that it requires about 1 hour to add all the aldehyde. The internal temperature is checked from time to time and should be held between 18 °C and 22 °C. The mixture is stirred for 10 minutes after the addition of the last of the aldehyde.

The mixture is then poured into 4 L of vigorously agitated cold water. From this point onward the protection of the product from light is extremely important. The stirring is continued for a few minutes; then the batch is filtered through Büchner funnel. The filter cake is recrystallized from 95% ethanol to give 55–60 g of pure material, melting at 132–133°. 1a

65% Nitric acid (20 mL) was added dropwise to a solution of 3,4-dimethoxyphenylacetic acid (10.00 g, 51.0 mmol) in THF (150 mL) at 0 °Cover 1 h. The solution was allowed to warm to room temperature and was stirred for 1 h. THF was removed in vacuo and the resulting dark mass dissolved in ethyl acetate. The solution was washed with water (2 x 50 mL), dried over MgSO4, concentrated in vacuo and the residue recrystallised from hexane:ethylacetate to give 4,5-dimethoxy-2-nitrophenylacetic acid (10.02 g, 82%) as an off-white solid. 1b

混酸作为硝化试剂反应示例

硝酸与硫酸组成的混酸是比硝酸更强的硝化剂，根据底物活性的高低可以使用普通的硝酸或发烟硝酸，这个方法可以顺利地得到多硝基取代的产物。

  A 5-L three-necked flask fitted with an all-glass addition funnel and two condensers is charged with 770 mL of concentrated sulfuric acid and 1.3 L of 90% fuming nitricacid. The solution is heated under gentle reflux, and a solution of (73 g, 0.4 mol) of 9-fluorenonein 840 mL of concentrated sulfuricacid is added from the dropping funnel over a 1-hour period.  After the fluorenone addition is complete, a solution of 950 mL of fuming nitric acidin 1120 mL of concentrated sulfuric acid is added dropwise during 8.5 hours to the gently refluxing reaction mixture. The heating jacket is turned off and the solution is allowed to stand for 10 hours. The reaction mixture is poured into 5 gallons of water in two 5-gal Crocks. The light yellow precipitate is washed withwater, twice by decantation, filtered, washed several times with water and sucked dry, and finally is dried in a vacuum oven at 80° for 10 hours. The yield of crude 2,4,5,7-tetranitrofluorenone, mp 249–253°, is 105–117 g (72–80%). This solid is recrystallized from 1.6 L of acetic acid containing 100 mL of acetic anhydride. The hot solution is filtered through a fluted filter and cooled rapidly to yield 80–86 g (51–54%) of 2,4,5,7-tetranitrofluorenone, mp 253.0–254.5°.2a