Organic compounds are mainly composed of oxygen, hydrogen and carbon. Organic matter is the material basis of life. Its characteristics mainly include:
Most organic compounds mainly contain carbon and hydrogen, and often contain oxygen, nitrogen, sulfur, halogen, phosphorus and so on. Some organic substances come from the plant kingdom, but most of them are artificially synthesized from oil, natural gas and coal. Compared with inorganic substances, organic substances are numerous, reaching millions. The carbon atoms of organic compounds have very strong binding ability and can combine with each other to form carbon chains or carbon rings. The number of carbon atoms can be 1, 2, thousands or tens of thousands, and many organic polymer compounds can even have hundreds of thousands of carbon atoms. In addition, isomerization is very common in organic compounds, which is one of the reasons for the large number of organic compounds. Except for a few organic compounds, it can generally burn. Compared with inorganic substances, their thermal stability is poor, and the electrolyte is easy to decompose when heated. The melting point of organic matter is relatively low, generally not exceeding 400℃. Organic matter is very weak in polarity, so most of it is insoluble in water. The reactions between organic compounds are mostly intermolecular reactions, which often require certain activation energy, so the reaction is slow and often requires catalysts and other means. Moreover, the reaction of organic compounds is complicated. Under the same conditions, a compound can often undergo several different reactions at the same time to produce different products.
Organic compounds in food:
1. Nutrients needed by human body: water, sugar (starch), fat, protein, vitamins and minerals.
Among them, starch, fat, protein and vitamins are all organic substances.
2. Starch (sugar) mainly exists in pasta such as rice and flour;
Grease mainly exists in edible oil, ice cream, milk and so on.
Vitamins mainly exist in vegetables, fruits, etc.
Protein mainly exists in fish, meat, milk and eggs.
Cellulose mainly exists in green vegetables, which is beneficial to gastric peristalsis and prevents constipation.
Among them, starch, fat, protein and cellulose are all organic polymers.
Classification:
1. According to the basic skeleton formed by the combination of carbon atoms, organic compounds can be divided into three categories: 1. Chain compounds, whose carbon atoms are connected to each other in chains, are also called aliphatic compounds because they are originally found in fats. 2. Carbocyclic compounds These compounds contain a cyclic structure composed of carbon atoms [2], so they are called carbocyclic compounds. It can be divided into two categories: alicyclic compounds: a kind of carbocyclic compounds with similar properties to aliphatic compounds. Aromatic compounds: Compounds containing benzene rings or condensed benzene series in their molecules. 3. Heterocyclic compounds: The rings that make up such compounds contain atoms of other elements except carbon atoms, which are called heterocyclic compounds.
II. Classification by functional groups
The main atoms or groups that determine the general properties of a class of compounds are called functional groups or functional groups. The chemical properties of compounds containing the same functional groups are basically the same.
[Edit this paragraph] Naming:
1. Common names and abbreviations
Some compounds often use common names according to their sources. It is necessary to master the structural formulas of some commonly used compounds, such as: lignin alcohol is methanol, alcohol (ethanol), ethylene glycol (ethylene glycol), glycerol (glycerol), carbolic acid (phenol), formic acid (formic acid), salicylaldehyde (o-hydroxybenzaldehyde), cinnamaldehyde (β-phenylacrotonaldehyde), crotonaldehyde (2- crotonaldehyde) and crotonaldehyde. There are also some compounds that commonly use its abbreviations and trade names, such as RNA (ribonucleic acid), DNA (deoxyribonucleic acid), aspirin (acetylsalicylic acid), coal phenol soap or lysol (47%-53% soapy water solution of xylenol), formalin (40% formaldehyde water solution), paracetamol (p-hydroxyacetanilide) and nicotine (nicotine).
2. Common naming (customary naming) method
It is required to master the meaning and usage of prefixes "positive, different, new" and "bo, zhong, number and pole".
Positive: stands for straight-chain alkane;
Heterogeneous: refers to alkanes with structure at one end of carbon chain;
New: generally refers to alkanes with structure at one end of carbon chain.
3. Systematic nomenclature
Systematic nomenclature is the focus of naming organic compounds, and we must master the naming principles of various compounds skillfully. Among them, the naming of hydrocarbons is the basis, while the naming of geometric isomers, optical isomers and multifunctional compounds is difficult and should be paid attention to. Remember the "order rule" to follow when naming.
1. Naming of alkanes:
The naming of alkanes is the basis of naming all open-chain hydrocarbons and their derivatives.
Steps and principles of naming:
(1) Choose the longest carbon chain as the main chain. When there are several identical carbon chains, the carbon chain containing substituents should be selected as the main chain.
(2) When the main chain is numbered, it starts from the end closest to the substituent. If there are several possible situations, each substituent should have as small a number as possible, or the sum of substituent positions should be minimized.
(3) Write the name in Arabic numerals to indicate the order of substituents, first write the order and name of substituents, and then write the name of alkane; When there are multiple substituents, the simple ones come first and the complex ones come last, and the same substituents are written in combination, and the number of the same substituents is represented by Chinese characters and numbers; Arabic numerals and Chinese characters are separated by a half-word line.
I. Identification methods of various compounds
1. Olefins, dienes and alkynes:
(1) carbon tetrachloride solution of bromine, and the red pipe section has been removed.
(2) potassium permanganate solution, purple leg.
4. Halogenated hydrocarbon: an alcohol solution of silver nitrate to generate silver halide precipitate; The precipitation rate of halogenated hydrocarbons with different structures is different, tertiary halogenated hydrocarbons and allyl halogenated hydrocarbons are the fastest, followed by secondary halogenated hydrocarbons, and primary halogenated hydrocarbons need heating to precipitate.
5. Alcohol:
(1) reacts with sodium metal to release hydrogen (identify alcohols with less than 6 carbon atoms);
(2) Identification of primary, secondary and tertiary alcohols with Lucas reagent, the tertiary alcohol becomes turbid immediately, the secondary alcohol becomes turbid after being placed, and the primary alcohol remains unchanged after being placed.
6. Phenols or enols:
(1) develop color with ferric chloride solution (phenol produces blue-purple color).
(2) Phenol and bromine water produce tribromophenol white precipitate.
10. Sugar:
(1) Monosaccharide can react with Torun reagent and Fehling reagent to form silver mirror or brick red precipitate.
(2) Glucose and fructose: Glucose and fructose can be distinguished by bromine water. Glucose can discolor bromine water, but fructose can't.
(3) Maltose and sucrose: With Torun reagent or Fehling reagent, maltose can produce silver mirror or brick red precipitate, but sucrose can't.
1, methane (natural gas) molecular formula: CH4 characteristics: the simplest organic matter.
2. The molecular formula of ethylene is C2H4. Features: The simplest olefin (with carbon-carbon double bond).
3. The molecular formula of ethanol (alcohol) is: CH3CH2OH characteristics: it is one of the most common organic substances.
4. The molecular formula of acetic acid (acetic acid) is CH3COOH. Features: same as above.
The molecular formula of benzene is C6H6. Features: ring structure.
2. Quality characteristics
Characteristics of physical characteristics
1) has high volatility and low melting point and boiling point.
2) Poor water solubility (mostly insoluble in water or water, but soluble in organic solvents)
Characteristics of chemical properties
1) flammability
2) Low melting point (generally not more than 400℃)
3) Solubility (soluble in organic solvents such as alcohol, gasoline, carbon tetrachloride, ether and benzene)
4) Poor stability (due to the influence of temperature, bacteria, air or light, organic compounds often decompose and deteriorate)
5) The reaction speed is relatively slow.
6) The reaction products are complicated.
Back to the textbook
1. Transformation relationship between common organic compounds
2. Comprehensive background related to isomers
3. The main types of organic reactions are summarized.
Dependent reactants involve functional groups or organic types and other precautions.
Consumption of halogen elements in halogenation reaction of alkanes, benzene, alcohols, carboxylic acids, esters and oils, halogenated hydrocarbons, amino acids, sugars, protein, etc. Such as ester hydrolysis, halogenation, nitration, sulfonation, alcohol etherification, amino acid peptide formation, saponification, polysaccharide hydrolysis, peptide and protein hydrolysis; The amount of sodium hydroxide consumed by ester saponification (pay special attention to the hydrolysis of ester formed by phenol and acid).
Addition reaction hydrogenation, oil hardening C=C, C≡C, C=O, the carbon-oxygen double bond in benzene carboxylic acid and ester is generally not added; C=C, C≡C can react with various reagents such as water, hydrogen halide, hydrogen and halogen, but C=O generally only reacts with hydrogen and hydrogen cyanide.
Dehydrohalogenated hydrocarbons, dehydrohalogenated alcohols, halogenated hydrocarbons, etc. In alcohol, molecules cannot be eliminated.
Oxidation reaction: organic matter combustion, catalytic oxidation of olefins and alkynes, silver mirror reaction of aldehydes, oxidation of aldehydes into acids, etc. Can occur in most organic substances. Both alcohols and olefins can be oxidized to aldehydes; The amount of reagents consumed in silver mirror reaction and copper oxide reaction of new hydrogen production; Potassium permanganate oxidizes benzene series.
Reduction reaction, hydrogenation reaction, hydrogenation reaction in which nitro compounds are reduced to complex organic compounds such as amine alkene, alkyne, aromatic hydrocarbon, aldehyde, ketone and nitro compounds, and the amount of H2 consumed.
Addition polymerization: ethylene type addition polymerization, butadiene type addition polymerization, copolymerization between different monoolefins, copolymerization between monoolefins and diolefins, and diolefins (some questions will also involve alkynes) are judged by monomers; Judging monomer structure from addition polymerization products.
Polycondensation reaction Phenol condensation, condensation of dibasic acids with dihydric alcohols, addition polymerization of amino acids with other phenols, aldehydes, polybasic acids with polyols, amino acids, etc. Writing of chemical equations.
4. Popularization of the transformation relationship among alcohol, aldehyde, acid and ester.
organic compound
(1) hydrocarbons and hydrocarbons
Alkane: CnH(2n+2) such as methane CH4.
Angle: 109 28'
It is the substance with the highest hydrogen content in alkanes.
Alkanes have a symmetrical structure, and the structural formula is shown in the book.
Methane is colorless and odorless, and its density is less than that of air.
CH4+2O2→CO2+2H2O Attention conditions
Substitution reaction: CH4+Cl2→CH3Cl+HCl Conditions: Pay attention to four substitution reactions.
Homologous: Similar in structure, but different from each other by one or more hydrocarbon groups.
Isomers: The molecular formula is the same, but the structure is different.
Methane does not react with strong acid, strong alkali and strong oxidant (in organic, strong oxidant = acidic potassium permanganate solution).
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C-C: saturated hydrocarbon C=C: unsaturated hydrocarbon.
React with oxygen, bright flame and a lot of black smoke.
Hydrocarbons containing C=C are called olefins, which are unsaturated, and the bond energy of carbon-carbon double bonds is different, so one is easy to break and undergo addition reaction to become a stable single bond.
It can react with strong oxidant and bromine. CH2=CH2+Br2→CH2Br-CH2Br Pay attention to the conditions. See the textbook for the specific structure.
Angle: 120.
It reacts with bromine, water, hydrogen and hydrogen chloride to produce corresponding substances. Pay attention to the conditions.
(2) Derivatives of hydrocarbons
Ethanol: CH3CH2OH
Both ethanol and dimethyl ether are C2H6O, but their structures are different. So 2mol ethanol reacts with sodium to generate 1mol hydrogen, and O-H is broken.
-OH hydroxyl, which is the group of ethanol. Groups determine the properties of organic compounds, and most reactions occur near groups.
It can be seen that hydroxyl groups have replaced hydrogen in ethane.
Reaction required for ethanol:
1. oxidation reaction: ignition under the conditions of CH3CH2OH+3O2→2CO2+3H2O.
2. Catalytic oxidation to produce formaldehyde. See the notes for details.
3. Acidic potassium dichromate aq turns green and the reaction is unnecessary.