These polyunsaturated fatty acids are called omega-3 because the third carbon from the end of the hydrocarbon chain is connected to its neighboring carbon by a double bond. Salmon, trout, and tuna are good sources of omega-3 fatty acids. Research indicates that omega-3 fatty acids reduce the risk of sudden death from heart attacks, reduce triglycerides in the blood, lower blood pressure, and prevent thrombosis by inhibiting blood clotting.
They also reduce inflammation and may help reduce the risk of some cancers in animals. Boundless vets and curates high-quality, openly licensed content from around the Internet.
This particular resource used the following sources:. Skip to main content. Search for:. Lipid Molecules. Learning Objective Differentiate between saturated and unsaturated fatty acids. Key Points Fats provide energy, insulation, and storage of fatty acids for many organisms.
Fats may be saturated having single bonds or unsaturated having double bonds. Unsaturated fats may be cis hydrogens in same plane or trans hydrogens in two different planes.
Olive oil, a monounsaturated fat, has a single double bond whereas canola oil, a polyunsaturated fat, has more than one double bond.
Omega-3 fatty acid and omega-6 fatty acid are essential for human biological processes, but they must be ingested in the diet because they cannot be synthesized. Show Sources Boundless vets and curates high-quality, openly licensed content from around the Internet.
For a compound to be saturated, there is one more hydrogen in a molecule when nitrogen is present. Therefore, we add the number of nitrogens N. Oxygen and sulfur are not included in the formula because saturation is unaffected by these elements. As seen in alcohols, the same number of hydrogens in ethanol, C 2 H 5 OH, matches the number of hydrogens in ethane, C 2 H 6. Each row corresponds to a different combination.
This corresponds to benzene containing 1 ring and 3 double bonds. However, when given the molecular formula C 6 H 6 , benzene is only one of many possible structures isomers. The following structures all have DoB of 4 and have the same molecular formula as benzene.
However, you can also determine the molecular formula and solve for the degrees of unsaturation by using the formula. Thus, the formula may give numerous possible structures for a given molecular formula.
If a few drops of bromine water is added to a saturated liquid hydrocarbon such as cyclohexane and shaken, decolourisation of the bromine water is NOT observed under standard laboratory conditions. The mixture will separate into 2 distinct layers, a colourless layer of cylcohexane floating on top of the yellow-brown bromine water layer at the bottom. If a few drops of bromine water is added to an unsaturated liquid hydrocarbon such as cyclohexene and shaken, the bromine water readily decolourises becomes increasingly less coloured until it is colourless.
If there is an excess of the unsaturated hydrocarbon, then the mixture will settle into 2 distinct but colourless layers with the colourless organic layer floating above the colourless aqueous layer. Concentrated aqueous solutions of potassium permanganate are a purple colour which fades through to a pink colour as the solution is increasingly diluted. Low molecular mass gaseous hydrocarbons can be bubbled through potassium permanganate solution.
If the hydrocarbon is saturated there will be no visible colour change the potassium permanganate solution stays pink-purple. If the hydrocarbon is unsaturated the potassium permanganate solution will decolourise pink colour fades to colourless. For colourless liquid hydrocarbons, add a few drops of potassium permanganate solution and shake.
These compounds are alcohols due to the presence of the OH functional group. These compounds are carboxylic acids due to the presence of carboxyl functional groups COOH. Qualitative tests for saturation become a bit trickier when a functional group, other than a double or triple bond, is present. Note that both bromine and hydrocarbons are soluble in tetrachloromethane so distinct layers will not form.
When exposed to strong light, alkanes will undergo a substitution reaction with the bromine which will produce hydrogen bromide, HBr, which is only slightly soluble in tetrachloromethane, so you can test the vapour built up above the solution in a test tube with blue litmus paper which will turn red due to the presence of HBr.
The reaction between bromine and an unsaturated hydrocarbon is an addition reaction so no hydrogen bromide HBr is produced, so if you test the gas above the solution in the test tube with blue litmus paper then the litmus paper will not change colour. This bromine solution is not usually used in schools because tetrachloromethane is a known carcinogen.
Exposure to strong light will produce a chemical reaction a substitution reaction with saturated hydrocarbons. A discussion of the possible types of reactions is beyond the scope of this very introductory tutorial.
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