Questions tagged [hydrocarbons]

Hydrocarbons are compounds containing only hydrogen and carbon atoms. This tag should be applied when a saturated or an unsaturated hydrocarbon is the main focus. For aromatic hydrocarbons, use [tag:aromatic-compounds] instead. For halohydrocarbons or other functional derivatives, use [tag:halides] or other relevant tags instead.

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21
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2answers
4k views

Is the ring or the chain chosen as the parent structure in octan-2-ylbenzene?

How would you name the above compound according to IUPAC rules? I see some sources say it is 2-phenyloctane, but ChemDraw and a few other sources say it is 2-octanylbenzene.
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2answers
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How do you name an alkene using IUPAC rules if the longest carbon chain in this alkene does not include the double bond?

For example, which is the right way to name this compound: Is it 2-bromo-4-methylenehexane or 4-bromo-2-ethylpent-1-ene? Does the larger number of carbon in a chain take priority, as in the former, ...
28
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5answers
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Is pyrene aromatic despite failing Hückel's rule?

Pyrene doesn't seem to be aromatic. However, sources claim that it is aromatic. Considerations: Pyrene is cyclic. ✓ Pyrene is flat (planar). ✓ Pyrene has 16 π electrons. Every atom in the ring ...
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3answers
2k views

Can a organic compounds such as hydrocarbons contain an ionic bond?

Can organic compounds like hydrocarbons have types of bonds other than covalent bonds? Can they also possess ionic bonds?
19
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2answers
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Cyclobutadiene - Jahn–Teller effect or not?

In transition metal chemistry the Jahn–Teller effect arises when the configuration of the metal ion and d orbital splitting set up a doubly degenerate state, which is less stable than a state without ...
4
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1answer
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Is an SN1 reaction possible in halobenzene?

Is an SN1 reaction possible in halobenzene? Will the phenyl carbocation be stabilized via resonance? Suppose the leaving group is very electronegative and the environment is protic. What then would ...
1
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2answers
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Why total heat of hydrogenation of 1,3-cyclohexadiene is more than that of benzene?

I'm told that heat of hydrogenation (HOH) is directly proportional to number of π bonds and inversely proportional to stability. So, is the aromaticity responsible for this? Also, what is the general ...
6
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1answer
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Color of precipitate formed on reaction of acetylene with Tollen's Reagent

I am asked to find the color of the precipitate formed by the passage of acetylene gas into an aqueous solution of ammoniacal silver nitrate. I thought ammoniacal silver nitrate was Tollen's reagent,...
4
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1answer
637 views

How should I name this branched alkyl substituent?

The parent chain is a decane (in black), but for the alkyl substituent (in red) I'm trying to decide between: 5-(1,2-dimethylpropyl)decane 5-(2-methylbutan-3-yl)decane 5-(3-methylbutan-2-yl)decane ...
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2answers
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Naming of 2-methylpropane

I can't understand why 2-methylpropane has/needs the 2 in front of it? It appears to me that if you were to add the methyl group at the first or last carbon on the chain then you get plain old butane ...
23
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3answers
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Why do cyclic hydrocarbons have higher boiling points than their acyclic isomers?

As pointed out in the comments to this question, cyclic hydrocarbons have higher boiling points than their acyclic isomers. The major attractive force for hydrocarbons should be the London forces, ...
14
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1answer
760 views

Can we synthesize alcohols by the photolysis of hydrogen peroxide?

As I was going through my revision of organic chemistry, I came across free radical substitution of alkanes with halogens. In a similar process where we use hydrogen peroxide, instead of chlorine, so ...
21
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3answers
452 views

Energy-efficiency aside, what are the chemical constraints on CO₂ capture and methanation?

Synthesising $\ce {CH4}$ from air and water (in a non-biological process) has been proposed as one form of energy storage. What are the chemical constraints at play here? That is to say, what sort of ...
7
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2answers
14k views

Does acetylene give a positive Tollens' test? If not, why is this so?

One of the uses of the Tollens' reagent is to confirm the presence of a terminal triple bond in a compound. Does acetylene give a positive Tollens' test? If not, why is this so?
6
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1answer
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Isomerisation of alkanes under Lewis acidic conditions

My textbook says: n-Alkanes on heating in the presence of anhydrous aluminium chloride and hydrogen chloride gas isomerise to branched chain alkanes. But no mechanism is given. After a little ...
5
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2answers
663 views

Why do alkenes with more surface contact have greater London forces?

Why is it that alkenes with greater surface contact have greater London forces? I thought greater London forces were dependent on the size of the molecules, or the number of electrons, rather than the ...
4
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1answer
1k views

How can I find the parent chains in these two compounds?

We recently started organic chemistry in school and I decided to make a computer program that names the compounds, so far it works with alkanes that do not have branched branches and I want to make it ...
7
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1answer
3k views

Predicting the products of the radical chlorination of propane

Question: When propane reacts with chlorine, two different monochloropropanes are formed. a) Name and show the full structural formulae of the two products. b) What kind of isomerism is ...
7
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2answers
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Creating ethane through electrolysis of vinegar

Some sources that I studied say that it is possible to produce ethane through the electrolysis of ethanoic acid. Would this work with vinegar (5-10% acid)? Also, other sources say that ethanoate ...
3
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1answer
76 views

What are “O-hydrocarbons”? A pharma translator's question (Russian to English, “О-углеводороды”)

A translator colleague is translating from Russian a plan for study of a number of leachable and extractable substances (pharmacology). This Russian text mentions one particular class of chemicals ...
2
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1answer
3k views

What is the empirical formula for kerosene?

Kerosene is a blend of hydrocarbons, so it doesn't have one chemical formula. But I'd like to find an (approximate) empirical formula giving the ratios carbon and hydrogen. I haven't found anything ...
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1answer
226 views

How to synthesize 6-methylhept-1-ene

What methods are there to produce this compound? What are its properties as a component of automobile petroleum? How does it impact on detonation resistance of automobile petroleum? I think that the ...
22
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2answers
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Are geminal disubstituted alkenes more stable than their cis/trans isomers?

I know for a fact that cis alkenes are less stable than trans alkenes due to steric repulsions. But what bugs me is the fact that why systems such as 2-methylprop-1-ene, where I believe steric ...
10
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1answer
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What is the directive influence of the tert-butyl group in electrophilic aromatic substitution?

We know that hydrocarbon side-chains on a benzene ring influence electrophilic substitutions by directing the incoming electrophile to attack at ortho and para positions. The following ...
12
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1answer
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Why alkanes containing even number of carbons can be packed more efficiently than alkanes with odd number of carbon atoms?

Variation of boiling and melting points of alkanes with increase in the number of carbons The odd-numbered alkanes have a lower trend in melting points than even numbered alkanes. This is because ...
38
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4answers
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Five-pointed crown alkane C25H40: does it exist?

My 4 year old granddaughter, playing with molecular models, began making a cyclopentane ring, each of whose carbons bore a spiro-connected cyclopentane ring of its own , in the manner of spiro[4.4]...
5
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1answer
413 views

Is 2a¹H-cyclopenta[cd]indene aromatic?

In this question, 2a1H-cyclopenta[cd]indene is said to be aromatic. My doubt is that the central C atom (connecting the three cyclic rings) is sp³ hybridized. So I think it should be non planar thus ...
6
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0answers
274 views

How does a 5th hydrogen bind to carbon atom in CH5[+]?

Can we bind a fifth hydrogen to a carbon atom if carbon is not in excited state? We have a big discussion in class and cannot clearly answer the question. If carbon atom excites an electron from $2\...
6
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1answer
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What is the purpose of ammonium chloride in anti hydrogenation of alkynes?

In my organic chemistry textbook, lithium is used to create a free radical of the alkynes, to then allow the anti addition of hydrogen to get an alkene. "The Dissolving Metal Reduction of Alkynes" is ...
6
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2answers
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What is the difference between Alkanes and Polymers?

As far as I understand, Polymers are long molecules made of smaller monomers which are Alkenes. But polymers don't have double bonds, so they are saturated. What is the difference between Alkanes and ...
6
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1answer
226 views

Hydroboration oxidation reaction on trans,trans,trans-1,5,9-cyclododecatriene with carbon monoxide

The given solution: I got this question in an entrance exam coaching test paper in India. Product P is easily covered by the mechanism of simple hydroboration-oxidation reaction, and I've understood ...
5
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1answer
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Least likely product of a hydrocarbon cracking reaction?

The hydrocarbon $\ce{C17H36}$ can be cracked. Which compound is the least likely to be produced in this reaction? A: $\ce{C3H8}$ B: $\ce{C4H8}$ C: $\ce{C8H16}$ D: $\ce{C16H34}$ Is it D because ...
4
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2answers
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Why do unsaturated hydrocarbons burn with a sooty flame while saturated hydrocarbons burn with a clear flame when burnt in the air?

Why do saturated hydrocarbons burn with a clean flame while unsaturated hydrocarbons burn with a sooty flame when burnt in air? My chemistry book says that it happens due to the amount of carbon ...
4
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1answer
117 views

Choosing Parent Chain, Complexity of Side Chains

Which parent chain should we choose for this structure? is it A or B? I followed the rule A-2.6, but it still got me confused. Both alternative A and B has the same number of side chains (2 side ...
4
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3answers
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Which has higher rate of hydrogenation - methyl propene or trans-2-butene?

Which has higher rate of hydrogenation- methyl propene or trans-2-butene? I know that cis-2-butene has a higher rate of hydrogenation than both of these due to steric reasons, but here, both of these ...
4
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2answers
1k views

Rate of catalytic hydrogenation of alkenes

What does the rate of catalytic hydrogenation of alkenes depend upon? What'd be the increasing order of rate towards catalytic hydrogenation of the following alkenes, A (2-methylpropene), B (cis-but-2-...
1
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1answer
116 views

Why are there distortions in electron cloud in molecules? How does increase surface area amplify these distortions?

In the physical properties of hydrocarbons,it is said that branched hydrocarbons have relatively less boiling point than it's linear form. From what I have learnt is that it is due to the increase in ...
1
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1answer
4k views

Why does radical chlorination and bromination of propane occur at different positions?

When propane reacts with chlorine, we will mostly (theoretically) get an isomer with a chlorine on the end. ($\ce{CH_3-CH_2-CH_2Cl}$). However, when propane reacts with bromine, we will mostly get an ...
10
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3answers
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Increasing the length of a carbon chain in an alkane

What would be the best reaction to increase the carbon chain length in an alkane? Preferably, it would be by one at a time; however, if that is not possible, just generally increasing the total length ...
9
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2answers
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Why does water attack the more substituted carbon in oxymercuration?

In hydration of an alkene by oxymercuration-demercuration, for an asymetrical mercunium ion, the more substituted carbon atom is attacked by water. Why is this the case? Since R groups are electron ...
8
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1answer
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How does WD40 displace water?

How does WD-40 displace water? Or does it even displace water? WD40.com explains what WD-40 stands for: WD-40® literally stands for Water Displacement, 40th formula. That's the name straight out of ...
6
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1answer
752 views

Can an SN1 reaction occur in compounds with the leaving group attached to a primary carbon, which can later rearrange?

Can SN1 reactions occur in compounds where the carbocation, even though is is initially $1^\circ$, can rearrange to form a more stable carbocation? Examples cases:
3
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1answer
2k views

Why is the molecular peak not observed in the mass spectrum of 2,2-dimethylbutane?

Why isn't the molecular weight of 2,2-dimethylbutane on the mass spectrum? I can tell that a $\ce{-CH3}$ group is removed just by the math, but I do not know the reason why. The molecular weight is 86 ...
3
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2answers
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Why is chlorine and not fluorine labelled as the most reactive halogen for halogenation?

The reactivity of halogenation in sunlight is as follows: $$\ce{F2}>\ce{Cl2}>\ce{Br2}>\ce{I2}$$ So why does we often label chlorine as most reactive halogen towards halogenation reaction?
2
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1answer
281 views

Why are the given compounds in a homologous series?

Why are the given compounds in one homologous series? $$\ce{CH3-OH}$$ $$\ce{CH3-CH2-OH}$$ $$\ce{CH3-CH2-CH2-OH}$$ $$\ce{CH3-CH2-CH2-CH2-OH}$$ I know that homologous series can be represented ...
2
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1answer
1k views

How are alkanes, alkenes, and alkynes homologous series since they have no functional group attached?

I understand that a homologous series is a group of compounds with the same functional group attached to it. I also know of an alternate definition of it as being a series of compounds with the same ...
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0answers
83 views

Can benzyne be trapped inside a polycyclic hydrocarbon?

I came across an article in my organic chemistry textbook, which told about how benzyne was trapped within a molecular container and stabilized for short periods of time before undergoing a Diels-...
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1answer
6k views

Combustion of saturated hydrocarbons vs combustion of unsaturated hydrocarbons

I read in my science book that saturated hydrocarbons burn with a blue flame (indicates complete combustion) and unsaturated hydrocarbons burn with a yellow flame (indicates incomplete combustion) due ...