The following substances do not contain ester bonds: A CH3OOCH B CH3COOOCCH3 C, CH3, 3COOC, CH3, 3,

Your teacher changed the c, and it doesn't contain ester bonds, ......

One more carbon atom should be removed: (CH3)3CcoOC(CH3)3 so that C has an ester bond.

The cooc of option c in the original question is a peroxide bond between two carbon atoms, i.e., -o-o-your teacher changed c to be connected by two carbonyl groups, i.e., -(co)-(co)-, so you have to remove another carbon, which is an ester bond, i.e., -(co)-o--(co)- is a carbonyl group].

It is true that the acetic anhydride is not an ester bond because it is obtained by dehydration of two molecules of acetic acid, not by dehydration of carboxylic acid with alcohol hydroxyl group, so it is not an ester bond.

In other words, if you don't change this question or change it as your teacher said, you have to choose BC. Change as I said, choose C.

The original C option (CH3)3COOC(CH3)3 does not contain ester bonds, and -cooc- is two ketone groups linked together.

The question is wrong, (ch3)3cooc(ch3)3, c has more than 4 bonds. Just draw the structural formula

It is also correct that the acetic anhydride is not counted as an ester bond!

The ** in acetic anhydride is ester bond selection B

Option D is CH3)3CCOOCC(CH3)3 obtained from CH3CoCOOH and CH3OH

Nor is it an ester.

It is a good ester, named trimethyl orthoformate, which is a kind of flavor and fragrance, and can also be used as a pesticide raw material.

If it belongs to ether, it should have only 1 oxygen atom (r-o-r' is an ether).

Proformic acid, CH(OH)3, hydration (addition) of C=O to formic acid is obtained by protoformic acid.

A, C4H8O2 belongs to the isomer of esters, is a saturated monoester, is an ester formed by formic acid and propanol, formic acid has only 1 structure, propanol can be known to be 1-OH substituted propane in the H atom, there are 2 kinds of H atoms in the propane molecule, there are 2 kinds of propanol formed, there are 2 esters formed, there are 2 esters formed by acetic acid and ethanol, only 1 kind of ethyl acetate, 1 ester formed by propionic acid and methanol, note 1 kind of methyl propionate, so there are 4 isomers of C4H8O2 belonging to esters, so A is correct;

When B, C4H8O2 belongs to carboxylic acid, it is butyric acid, 2-methylpropionic acid, a total of two isomers, so B is correct;

C. When C4H8O2 belongs to hydroxyaldehyde, it can be 2-hydroxybutyraldehyde, 3-hydroxybutyraldehyde, 4-hydroxybutyraldehyde, 2-methyl-2-hydroxypropionaldehyde, 2-methyl-3 hydroxypropionaldehyde, a total of 5 isomers, so C is wrong;

d. There are isomers containing six-membered rings in the molecule: , so d is correct and c is chosen

A c c is composed of 1 δ key and 2 δ keys, so A is not selected;

b only has a single c-h key, which is a δ key, so b is selected;

The three bonds of c n n contain 1 bond and 2 bonds, so c is not selected;

The structural formula of d CO2 is O=C=O, and if it contains a double bond, it must contain a bond, so D does not choose B

A oil is a type of ester formed by glycerol and higher fatty acids, ethyl acetate is an ester formed by the reaction of acetic acid and ethanol, the number of -cooc- is different, and it does not belong to the same system, so a is wrong;

B ester dehydration of alcohol in leadification reaction, dehydroxyl of carboxylic acids, CH3CO18OC2 under acidic conditions

The hydrolysate of H5 is CH3

CO18OH and C2

h5oh, so b is correct;

c There are 2 positions of Shenpei H in propane, then there are 2 isomers with the molecular formula C3H7Cl, so C is correct;

D dipeptide contains 1-conh-, glutamate molecule asymmetry, condensation can form up to 2 dipeptides, the molecular formula is C3H7O2

n、c9h14o5n2

Therefore d is correct; So choose A

a．hoch2

The functional groups in CHO are hydroxyl and aldehyde groups, which do not belong to esters, so A is wrong;

b．clch2

The functional group in COOH is chlorine atom and carboxyl group, does not contain ester group, and does not belong to ester group, so B is wrong;

c．ch3cooch3

It is methyl acetate, and the molecule contains a functional ester group, which belongs to the ester group, so c is correct;

d．<>

It contains an ether group, which belongs to the ether group and does not belong to the ester group, so D is wrong;

Therefore, C

a．ch2o2

It is formic acid, which must contain -cho, so A is not selected;

b Excavation C2

H4O is acetaldehyde, which must contain -CHO, so B is not selected;

c．c3h6

O3 may be scrambled mode HCOOCH2

ch2oh, judging Li Oak may contain -cho, so C is selected;

d．c4h10

O4 is butaerythrisol and does not contain -cho, so D is not selected;

Therefore, C

C Correct Answer: C

a. It may be formic acid; b. At least two oxygen atoms in the ester group; d. It can only be saturated alcohol or ether.