10: Organic chemistry Flashcards
What has the lowest solubility
Propanal is roughly 500 times more soluble in water than propane, due to dipole-dipole attractions between the carbon-oxygen double bond and the hydrogen-oxygen single bonds in water. Both 1-propanol and propanoic acid are capable of hydrogen bonding with water, making them both highly soluble in it. Propane, a non-polar molecule, has the lowest solubility in water.
Fill in the blanks: The oxidation of propan-1-ol with acidified potassium dichromate with distillation will produce ______The oxidation of propan-1-ol with acidified potassium dichromate heated under reflux will produce
______
Propanal
&
Propanoic acid
What causes a higher boiling point in straight chain alkanes
As the molar mass increases, the strength of the London dispersion forces between the molecules also increases, which results in an increase in boiling point.
Which conditions are needed to obtain a high yield of ethanal when ethanol is oxidized using acidified potassium dichromate(VI), K2Cr2O7 (aq)?
I. React with an excess of ethanol
II. Reaction mixture heated under reflux
III. Distillation of product during the addition of the oxidizing agent
I & III
III because This process heats the mixture and separates compounds based on their boiling points. Since ethanal has a lower boiling point than ethanol or ethanoic acid, the reaction mixture can be heated above the boiling point of ethanol but below the boiling points of ethanol or ethanoic acid, collecting ethanal as the distillate.
not II because If the reaction mixture is heated under reflux with excess oxidizing agent, the conditions will favour complete oxidation, forming ethanoic acid as the dominant product.
What is the most likely product for the reaction of Br2 with benzene using an aluminum bromide catalyst.
Benzene can, undergo electrophilic substitution reactions to produce bromobenzene and hydrogen bromide as products. In an electrophilic substitution reaction, one hydrogen atom is replaced with an electrophile (in this case one bromine atom). It is unlikely to substitute two hydrogen atoms with two bromine atoms, as the electrophile is a positively charged species. Br2 in the presence of the AlBr3 catalyst is capable of forming a Br+ electrophile, indicating that only one bromine atom would substitute a hydrogen atom.
Carboxylic acid
Carboxylic acids have a COOH group on the terminal carbon. Be careful not to confuse the class with the functional group - the functional group in this molecule is the carboxyl group (COOH).
What is the product formed when ethanol and butanoic acid are heated with concentrated sulfuric acid?
Ethyl butanoate
Esters are formed by the reaction between a carboxylic acid and an alcohol when they are heated with concentrated sulfuric acid. The general name of the compound formed is an alkyl alkanoate where the alkyl is from the alcohol and the alkanoate from the carboxylic acid. In this example, the alcohol is ethanol which becomes ethyl and the carboxylic acid is butanoic acid which becomes butanoate.
hich of the following organic molecules will not react with Cl2 in the dark?
A: CH3CH2CH3
B: CH2CH2
C: CH2CHCH2CH3
D: CH3CHCHCH3
A
CH3CH2CH3 is an alkane, whereas CH2CH2, CH2CHCH2CH3 and CH3CHCHCH3 are all alkenes.
Alkanes can undergo reaction with a halogen via the free radical mechanism; however, initiation of this reaction is required using UV light to form.
Alkenes on the other hand are more reactive than alkanes and undergo addition reactions.
A hydrocarbon, X, decolourises aqueous bromine, Br2 (aq). What could be X?
A: CH4
B: C3H6
C: C6H14
D: C5H12
B
C3H6 is an unsaturated hydrocarbon that contains a carbon to carbon double bond. The test for unsaturation is to react the compound in question with bromine water. The bromine water is decolourised by the unsaturated hydrocarbon, in this case propene. The colour change is brown to colourless. The remaining choices are all alkanes which are saturated hydrocarbons.
