How many covalent bonds are counted for carbon carbon double bonds? Properties of chemical carbon ca

The structure of the hydroxyl group on the carbon-carbon double bond c=ch oh structure, that is, "enol", is also a substance that can be "isomerized" and converted into aldehydes or ketones. The one on the far right is the "enol" that the hydroxyl group is attached to the carbon that forms the carbon-carbon double bond, which can be transferred by a reversible reaction (the acid group formed after the ionized hydrogen ion in the middle) to transfer the hydrogen of the hydroxyl group to another carbon atom that was originally a double bond, so that it becomes a sp2 hybrid to sp3 hybridization, and the original double bond is transferred between the carbon and oxygen atoms, and is converted into the leftmost structure containing a carbonyl group (or aldehyde group) (please understand the pink color represents the bond between c and o). Among them, if it is C=CH OH, it is converted to aldehyde; If it is C=Cr OH, it is converted to ketones.

In most cases, ketone structures are much more stable than enol structures, such as: (Liu Zaiqun. Organic Chemistry Study Notes.

Beijing: Science Press. ppt courseware) The enol-like structure corresponding to acetone accounts for only 1%, that is, for every 100 acetone molecules, only 1 is isomerized into enol (forgive me for not naming it), and the remaining 99 acetone molecules; Alternatively, 99 out of every 100 CH2C(CH3)OH molecules will be converted to acetone, leaving only 1 molecule, so we would think that substances with a structure of the enol type usually do not exist (and even if they exist, they are unstable and will be converted into lower energy and more stable isomers - ketones or aldehydes).

Acetylacetone, because its structure is relatively "alternative", the enol-like structure can form intramolecular hydrogen bonds, and it will also form a relatively stable six-membered ring structure, and the two double bonds are also conjugated, so the enol-like structure is "lower energy, more comfortable posture" than the ketone structure, and when the molecule is isomerized, it will choose more enol-like structure. The ratio has been reversed from 1:99 to 76:

24。The equilibrium constant gradually increases from 10 -8, 10 -7, 10 -6, and 10 -4. The equilibrium constant of acetylacetone is, which is 76:, as mentioned above

24=. The equilibrium constant of the last one actually reached 10 14, which is the equilibrium constant of hydrogen ions and hydroxide ions to form water molecules! That's a lot bigger than the 10 5 perfectly reactive line!

If you take a closer look, it turns out that its enol-like structure is phenol! It's a bug! A benzene ring is formed, and of course the enol-like structure is far more stable than this ketone-like structure.

In fact, enols and phenol are still very similar, for example, they can have a color reaction with ferric chloride, and the Kekuler formula can still explain some phenomena) <>

Under certain conditions (such as normal temperature and pressure), we are always unable to obtain its theoretical purity. If there is also an inert container of variable volume with some nitrogen dioxide (e.g. 100 a mol) in it, then if it is kept at standard atmospheric pressure and 27 conditions, it will soon reach equilibrium and become a mixture of 20 mol of nitrogen dioxide and 40 mol of nitrogen tetroxide; If it is changed to standard atmospheric pressure and 100, it becomes a mixture of 90 amol of nitrogen dioxide and 5 mol of nitrogen tetroxide. This "no pure nitrogen dioxide" question used to be tested in high school.

The difference between the example of nitrogen dioxide and the example of fluorine is that only one reactant of nitrogen dioxide can undergo a chemical reaction – a dimerization reaction that is prone to occur because the nitrogen dioxide molecule contains single electrons. In addition to nitrogen dioxide can be dimerized, we also have cyclopentadiene, which is also a substance that can be dimerized at room temperature at atmospheric pressure (25), do you see that this is actually a Diels-Alder reaction? (As a result, we "don't have pure cyclopentadiene," or the measured relative density ratio of cyclopentadiene gas to hydrogen is always larger.)

Cyclopentadiene, like nitrogen dioxide, is in the gaseous state, low temperature is conducive to polymerization, while high temperature is conducive to depolymerization (dimer cyclopentadiene is completely decomposed into cyclopentadiene; Nitrous tetroxide is completely decomposed into nitrogen dioxide at 140), why? Let's try to explain it. Therefore, in the color illustration at the front of the Chemistry Elective 4 textbook, the color of nitrogen dioxide in ice water is light, and the color of nitrogen dioxide in hot water is dark.

Turning back to the topic, the propadiene substances and enols mentioned by the subject can also have chemical reactions on their own, so the type of reaction they are "isomerization reactions". = Prodiene can be converted into its isomer propylene: , at 5, its standard equilibrium constant is 10, that is, after reaching equilibrium, the partial pressure of propylene is 10 times that of propadiene, since they are all gases, the molar mass is also the same, and the number of molecules before and after the reaction does not change, so it also indicates that the ratio of the amount or mass of their substance is 10.

So, at 5 hours, about 909 out of every 1000 propadiene molecules will be converted to propylene molecules, leaving only 91 propadiene molecules. When the temperature is changed to 270, the standard equilibrium constant drops to , which means that approximately 820 out of every 1000 propadiene molecules will be converted to propyne molecules, leaving only 180 propadiene molecules. So, the accumulation of diolefins is:

The molecule of this substance exists, but it is prone to isomerization reactions, which are converted into its isomers, so that the free energy is reduced and the system is more stable. Therefore, the hydrolysates of hexagonal crystals are magnesium hydroxide and propyne and a small amount of propadiene. (Protadiene can be further combined with hydration to form acetone) <>

The interchange of allotropes can also be regarded as "no need to add other reactants", and theoretically, under the conditions of a certain temperature and pressure, a certain allotrope is more stable, and it stands to reason that it should also be transformed into a more stable element. For example, at room temperature and pressure, graphite is more stable than diamond from the phase diagram, so why hasn't diamond become graphite? In fact, the reason is the same as the vinyl alcohol in the previous sections, although graphite is more stable in thermodynamic equilibrium, the reaction rate can still be very slow, so slow that in the absence of catalysts, the equilibrium state cannot be reached in a lifetime, and even the change is not detected, that is, "kinetic stability".

So don't worry about the diamond ring you bought yesterday and turn it into a pencil lead when you sleep. What is the saying? "A diamond is eternal, and a diamond is eternal".

The properties of carbon-carbon double bonds are mainly manifested in oxidation, addition, and polymerization.

The oxidant is mainly acidic potassium permanganate solution, and the phenomenon is the purple color of potassium permanganate solution, which can be used to distinguish alkanes and olefins.

The addition reaction is mainly with hydrogen and halogen elements. If it is reacted with bromine water or carbon tetrachloride of bromine, the yellow color of bromine water or the orange yellow color of bromine carbon tetrachloride solution will fade, and one mole of double bonds can be added to one mole of hydrogen or bromine in the reaction.

The polymerization reaction is divided into homopolymerization and copolymerization (homopolymerization: monomer is one. Co-Convergence:

Monomers are two or more of them, with binary copolymerization, ternary copolymerization, etc.). If it is self-polymerizing, then there are generally two or four carbon atoms on the main chain of the chain. If there are four carbon atoms, the monomer is a conjugated diolefin (two double bonds separated by a single bond).

In the case of copolymerization, the number of carbon atoms on the main chain of the link may be four, six, and so on. The two main points that everyone is clear here are: there are double bonds in the polymerization links of alkynes and conjugated diolefins; Co-gatherings produce by-products.

In addition, in organic synthesis, a reaction called ozonation of olefins is often given in the form of information questions, that is, two bonds are broken and each is connected to an oxygen.

Hello Lou Lou. The first substances that contain carbon-carbon double bonds are called olefins (without other functional groups).

Addition reaction: A reaction in which a double or triple bond in an organic molecule is broken and other atoms or clusters are added (combined).

Reacting with halogen element, bromine water can fade, CH2 CH2 + BR2 CH2B-CH2BR

When there is a catalyst, it can also react with addition to H2O, H2, HCl, HCN, etc.

Oxidation reaction: iCombustion IIFade KMNO4 H+.

This is the embodiment of reductiveness

Catalytic oxidation: 2CH2 CH2+O2

In 2CH3CHO organic reactions, the oxidation reaction can be seen as adding oxygen atoms or subtracting hydrogen atoms to organic molecules, and the reduction reaction can be seen as adding hydrogen atoms or subtracting oxygen atoms from the molecules. The above can be referred to as "oxygenation and dehydrogenation for oxidation; hydrodeoxygenation for reduction".

Polymerization: The reaction in which small molecule olefins or substituted derivatives of olefins are combined into polymer compounds through addition reaction under the action of heating and catalyst, which is called addition polymerization reaction, referred to as addition reaction.

If you have any questions, please ask.

Both oxidizing and reducing properties are caused by the instability of one of the carbon-carbon double bonds, which is susceptible to attack.

1. Addition reaction: with halogenated hydrocarbons, halogen elements, hydrogen, oxygen (to generate unstable ethylene oxide), etc.

2. Oxidation reaction: fade the acidic potassium permanganate solution; Combustion (bright flame, black smoke) 3, polyaddition reaction (addition and polymerization): ethylene itself, ethylene and propylene (polyethylene propylene).

Carbon-carbon double bonds are oxidizing, and yes.

However, it cannot be said that olefins are oxidizing, because olefins are unsaturated hydrocarbons. If it is a hydrogenation reaction, it is counted as a reduction reaction.

Generally, it reflects reductiveness;

It is the oxidation of double bonds;

Olefins are unsaturated hydrocarbons, which are easily oxidized and have reducibility;

If you have any questions, please ask!

Carbon-carbon double bond. -c=c-

Addition reactions, with H2, X2, Hx, HCN, etc.

The acidic potassium permanganate solution fades and the oxidation reaction occurs.

3.The polyaddition reaction occurs.

Chemical properties of hydroxyl group.

Carbon-carbon single bond:Both are carbon-carbon bonds, and the bond length is the longest. Carbon-carbon double bond, bond length second.

Carbon-carbon triple bond with the shortest bond length. The carbon-carbon single bond length should be m(o)> the average distance between the two nuclei in a molecule with greater attraction is called bond length. For example, the nuclear spacing between two hydrogen atoms in a hydrogen molecule is 76 pm, and the bond length of h—h is 76 pm.

Carbon-carbon double bond. Refers to the hybridization of one 2S sublayer and two 2P sublayers of carbon into three sp2 hybrid orbitals. These three sp2 hybrid orbitals are distributed in the same plane.

The bond energy is greater than that of a single bond. A triple bond is a heavy bond (covalent bond) composed of three pairs of shared electrons between two atoms in a compound molecule, called a triple bond (formerly known as triple bond).

The three keys are often represented by three **.

Carbon-carbon triple bond:The carbon-carbon triple bond has 2 bonds. There is only one bond, and the rest are bonds, i.e., the carbon-carbon triple bond has one bond and two bonds; The carbon-carbon double bond has one bond, 1 bond.

The carbon-carbon triple bond is the shortest in length, unstable, easy to add, easy to oxidize, can make bromine water and acidic potassium permanganate fade, do not replace, add hydrogen than double bond 1 times.

The above content refers to Encyclopedia - Carbon Carbon Triple Bond.

The above content refers to Encyclopedia - Carbon-carbon double bond.

Carbon-carbon double bonds, the most common.

It is also a carbon-carbon double bond, but it is uncommon (usually there is no hydroxyl group on the double bond carbon) <>

Carbon-oxygen double bond (forming aldehyde group).

Carbon-oxygen double bond (formation of carbonyl group silently).

5.-ch2-ch2-ch2-o-.(Four atoms into a ring, connected end to end) <>

6.(-ch2-o-ch-)-ch3.(Two carbons and one enlightenment are absolutely macro-potato oxygen rings).

7.(-ch2-ch2-ch-)-oh.(three carbons into rings) <>

The carbon-carbon double bond counts two covalent bonds. Consists of a single C-C bond and a C-C bond:

Pi Bond and Sigma Bond

The carbon-carbon double bond refers to the hybridization of one 2S sublayer and two 2P sublayers of carbon into three sp2 hybrid orbitals. These three sp2 hybrid orbitals are distributed in the same plane. The bond energy is greater than that of a single bond.

The outermost orbital of carbon is one s orbital and three p orbitals, so there is still one p orbital left after hybridization. This p orbital is spatially perpendicular to these three sp2 orbitals. Due to the repulsive action between the electrons, and the repulsive action is averaged by these three sp2 hybrid orbitals.

The bond angle between the three bonds is 120°. Therefore, the configuration of carbon-carbon double bonds is a planar regular triangle.

1. The stability is not the same.

Carbon-carbon single bond: the least stable;

Carbon-carbon double bond: medium stability;

Carbon-carbon triple bond: the most stable;

2. The length is not the same.

The length of a single bond is the longest, followed by a double bond, and the shortest triple bond.

3. The key energy is different.

Carbon-carbon single bond: minimum bond energy;

Carbon-carbon double bond: medium bond energy;

Carbon-carbon triple bond: the bond energy is the largest;

It's computer literacy

C=C is very tightly bound, so the bond can be destroyed greatly, and it needs to be destroyed, and the energy required is large.

The bond length is a little longer than a single bond.

Generally speaking, the shorter the bond length, the more stable the chemical bond.

There are several types of carbon-carbon bonds, each of which has a different bond length.

Single Button, Double Bond, and Three Bonds.

The longer the bond length, the smaller the bond energy, and vice versa, the shorter the bond length, the greater the bond energy.

The bond length of a double bond is not equal to the sum of the bond lengths of two single bonds, and in the same way a triple bond bond is not equal to the bond length of a single bond plus the bond length of a double bond.

The length of the bond length is mainly regarded as the overlap of the bond orbitals, and in addition to the carbon-carbon Sigama bond formed by ethane, ethylene, and acetylene, ethylene, acetylene, and the side overlap of the hybrid orbital p electron cloud, and the bond length is shorter than that of ethane.

But this length is not fixed, even the bond length of the same carbon-carbon bond is different in different compounds, and the carbon-carbon bond length we generally find is an average.

Ethane and bromine produce an oily substance under light: it reacts with pure liquid bromine (br2) and undergoes a substitution reaction. One bromine atom replaces one hydrogen, and the replaced hydrogen with another bromine atom is formed under the condition of illumination).