15. Rank the following compounds in order of increasing Ka. The first compound in your ranking shou the lowest Ka. H H H CH 2 H3 H (a) 1<2<3 (b) 3 <2<1 (c)2<1<3 (d)3
Reactive Intermediates
In chemistry, reactive intermediates are termed as short-lived, highly reactive atoms with high energy. They rapidly transform into stable particles during a chemical reaction. In specific cases, by means of matrix isolation and at low-temperature reactive intermediates can be isolated.
Hydride Shift
A hydride shift is a rearrangement of a hydrogen atom in a carbocation that occurs to make the molecule more stable. In organic chemistry, rearrangement of the carbocation is very easily seen. This rearrangement can be because of the movement of a carbocation to attain stability in the compound. Such structural reorganization movement is called a shift within molecules. After the shifting of carbocation over the different carbon then they form structural isomers of the previous existing molecule.
Vinylic Carbocation
A carbocation where the positive charge is on the alkene carbon is known as the vinyl carbocation or vinyl cation. The empirical formula for vinyl cation is C2H3+. In the vinyl carbocation, the positive charge is on the carbon atom with the double bond therefore it is sp hybridized. It is known to be a part of various reactions, for example, electrophilic addition of alkynes and solvolysis as well. It plays the role of a reactive intermediate in these reactions.
Cycloheptatrienyl Cation
It is an aromatic carbocation having a general formula, [C7 H7]+. It is also known as the aromatic tropylium ion. Its name is derived from the molecule tropine, which is a seven membered carbon atom ring. Cycloheptatriene or tropylidene was first synthesized from tropine.
Stability of Vinyl Carbocation
Carbocations are positively charged carbon atoms. It is also known as a carbonium ion.
![**Question 15: Ranking Compounds Based on Ka**
**Objective:** Rank the following compounds in order of increasing acid dissociation constant (Ka). The first compound in your ranking should have the lowest Ka.
**Compounds:**
1. ![H-C≡C-H](data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 20 20'%3E%3Cpath d='M0 10h10v10H0z' fill='none' /%3E%3Ctext x="0" y="15" font-family="Arial" font-size="20" fill="black"%3EH-C≡C-H%3C/text%3E%3C/svg%3E)
2. ![CH4](data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 20 20'%3E%3Cpath d='M0 10h10v10H0z' fill='none' /%3E%3Ctext x="0" y="15" font-family="Arial" font-size="20" fill="black"%3ECH4%3C/text%3E%3C/svg%3E)
3. ![benzene](data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 20 20'%3E%3Cpath d='M0 10h10v10H0z' fill='none' /%3E%3Ctext x="0" y="15" font-family="Arial" font-size="20" fill="black'%3Ebenzene%3C/text%3E%3C/svg%3E)
**Ranking Options:**
(a) 1 < 2 < 3
(b) 3 < 2 < 1
(c) 2 < 1 < 3
(d) 3 < 1 < 2
(e) 2 < 3 < 1
**Note:** The equations denote the structural representations of the compounds:
- 1: H-C≡C-H (ethyne)
- 2: CH4 (methane)](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F82d2dc19-90fa-4ae1-a10f-38c18ceb28bc%2F196aa657-7414-475b-8529-87cb44d9c2a9%2Ftezoig.png&w=3840&q=75)
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