The acid and its derivative, the carboxy acid

NetworkChapter 16 Pyric acid and its derivativeRCOOH) is the most important class of
organic
acid. It can be thought of as a
compound
produced when hydrogen atoms in hydrocarbon molecules are replaced by a carboxyl (or -COOH), a hydrocarbon group. There are many chemical reactions that can occur with nitric acid. When the hydroxyl in the carbide is replaced by other atomic groups, a derivative of pyrethroic acid is formed, mainly pyrethroides, ayl halogen, anhydride and alamide.first section of pyric acidpyric acid is often found in nature in free state or in the form of salt or esters in animals and plants, is a very closely related to the pharmaceutical class of compounds.First, the classification and naming of carboxy acid according to the hydrocarbon-based structure, carboxy acid can be divided into adipose carctic acid (saturated and unsaturated), lipid ring carboxy acid and aromatic carboxy acid. According to the number of carboxyls contained in the nicotic acid molecules, it can be divided into phosphonates and polyic acids. Chained polyacetic acid (both saturated and unsaturated) is commonly referred to as fatty acids. The classification of pyric acid can be found in Table 16-1.table 16-1 classification of pyridine
adipose carb acid saturated carb acid binary carb acid CH
2
COOH HOOC-COOH acetic acid (acetic acid) acetic acid (herbic acid) insulated ch
2
-CH-COOH HOOCCH-CHCOOH Acrylic acid butyl diacids The ring has been alkalic acid 1,2-cycloacetic acid aromatic benzoic acid phthalates
many carpic acids can be obtained from natural products, so they are often commonly known according to the original source, such as antic acid, acetic acid, grass acid and so on. The system nomenclat of pyric acid is similar to aldehyde. Saturated fatty acids are named after the longest carbon chain, including carboxyl carbon atoms, and are called an acid based on the number of carbon atoms in the main chain, starting with the carboxyl carbon atoms. For example, whenunsaturated fatty acids are named, the main chain shall be the longest carbon chain, including the carbon atoms of the carboxyl carbon and the carbon atoms of each carbon carbon bond, numbered from the carbon atom of the carboxyl carbon and indicating the location of the heavy bond. For example:binary acid is named after the longest carbon chain, including two carboxyl carbon atoms, according to the number of carbon atoms in the main chain called "a certain biic acid." For example, when the -based carboxyl is named directly on the lipid ring, the end of the word "carboxylic acid or nitric acid" may be added after the name of the lipid ring hydrocarbon; In addition, the grease ring can be named as a substitute for the grease ring, whether it is directly connected to the lipid ring or to the lipid ring side chain. For example scented acid can be named as an aromatic base substitute for fatty acids. For example:II, the physical properties of pyridine low-grade saturated fatty acids (foric acid, acetic acid, propylene acid) are liquids with a strong irritating odor;low-grade fatty acids are soluble in water, but with the increase of relative molecular mass, the solubility in water decreases, so that they are insoluble or insoluble in water and soluble in organic solvents.the boiling point of pyric acid is higher than that of alcohols of similar molecular mass. For example, the relative molecular mass of foric acid and ethanol is the same, but the boiling point of ethanol is 78.5 degrees C, while foricic acid is 100.5 degrees C. This is because the hydrogen bonds between the molecules of pyric acid can be synthesized with hydrogen bonds to synthesize the djusts, and the hydrogen bonds between the molecules of pyric acid are more stable than between the molecules of alcohol. For example, the hydrogen bond between ethanol molecules can be 25.94kJ,mol
-1
, while the hydrogen bond between foracetic acid molecules can be 30.12kJ
mol. Low-grade pyric acid is present in the form of a two-connective body even in the gaseous state.melting point of saturated fatty acids changes jaggedly with the increase of carbon atoms in the molecule (Figure 16-1). The melting point of an even number of carbon atoms is higher than that of its two adjacent molecules containing an odd number of carbon atoms. This may be due to the fact that the even carbon atom carboxy acid molecules are more symmetrical and arranged more closely in the crystal. The physical constants and pKa values of some pic acids are found in Table 16-2.table 16-2 Physical constants of some carpic acid and pKaName Constructed Melting Point/C Boiling Point/C Solubility g(100g water)-1 PKa (25 oC) pKa1, pKa2 methic acid HCO OH 8.4 100.5 ∞ 3.77 AC CH
3
COOH 16.6 118 ∞ 4.76 AC CH
3
CH
2
COOH -22 141 ∞ 4.88
CH
3
ch
2
ch
2
COOH -4.7 162.5 ∞ 4.8 2 CH
3
(CH
2
)
3
COOH -35 187 3.7 4.81 hexic acid CH
3
(CH
2).
)
4
COOH -1.5 205 0.4 4.84 orthophate CH
3
(CH
2
)
5
COOH -11 223.5 0 .24 4.89 positive
CH
3
(CH
2
)
6
COOH 16.5 237 0.25 4.85 ch
3
(CH
2
)
7
COOH 12.5 2544.96 ch
3
(CH
2
)
8
COOH 31.5 268 soft
CH
3
(CH
2
)
14
COOH 62.9 269 (13Pa) stingric acid CH
3
( CH
2
)
10
COOH 69.6 287 (13Pa) acrylic CH
2 -CHCOOH 13 1414.26 HOOC-COOH 1898.6 1 .46 4.40 hetdiacid HOOC (CH
2
)
4
COOH 151 276 1.5 4.43 5.52 shunbutylate