Interesting Questions, Facts and Information
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Interesting Questions, Facts, and Information
Elimination. Alkenes are commonly made by reacting an alkyl chloride or an alcohol with a base, resulting in the formation of an alkene by the elimination of hydrogen chloride or water respectively.
|In the laboratory, which two classes of compound may be reacted together without any other activating reagents to prepare an amide?||Organic Chemistry
Acid chloride and amine. Amides can't be made from amines and carboxylic acids in the laboratory because they will undergo an acid-base reaction to give a carboxylate anion and an ammonium salt.
CnH2n. Alkenes are known as 'unsaturated' hydrocarbons and contain a carbon-carbon double bond.
CnH(2n+2). Alkanes are known as 'saturated' hydrocarbons. The word 'hydrocarbon' is derived from the two elements that make up alkanes - hydrogen and carbon. Alkanes are known as saturated because they contain only carbon-carbon and carbon-hydrogen single bonds and thus contain the maximum number of hydrogens per carbon.
Protonation of the hydroxyl group. Protonation is always the first step because OH is a poor leaving group, and (+)OH2 is a good leaving group. The elimination can only occur after protonation, thus forming the double bond.
|If branching of the side chain in the product is a problem in Friedel-Crafts alkylation, how can a product with an unbranched side chain be reached?||Basic Organic Chemistry
Friedel-Crafts acylation followed by Clemmenson reduction. Ok, this one was obvious--none of the incorrect answers make any sense. (While the tertiary carbocation cannot be avoided in Friedel-Crafts alkylation, there is definitely still a way to synthesize the desired product--never give up!)
carrot. Beta-carotene is a naturally-occurring pigment responsible for the bright orange colour of carrots (I guess it's not hard to see where its name comes from!). Beta-carotene has an extremely important role in relation to vitamin A, the vitamin that is essential for our eyes. Vitamin A is an alcohol (a molecule containing an -OH group) whose structure is exactly one half of that of beta-carotene. Cleavage of beta-carotene by an appropriate enzyme gives two molecules of vitamin A.
Thanks for playing this quiz; I hope you enjoyed it. If you did, check out my other quizzes in the Organic Chemistry section.
|Having had enough of crying over my chopping board, I move on to chopping another vegetable. I can't resist tasting a little bit of what I've chopped and the taste of capsaicin explodes in my mouth. Which vegetable am I chopping?||The Very Edible Organic Chemistry Quiz
chillies. Capsaicin (and the related capsaicinoids) is the chemical present in chillies (and all peppers) that gives them their well-known heat. Capsaicin is another example of an amine (see question 7). When eaten, the capsaicinoids in chillies bind to a receptor in the lining of the mouth. This is the same receptor that registers pain from heat, thus the effect is a burning feeling. If you find yourself in dire straits after eating a too-hot chilli, you'll get relief from drinking a glass of milk.
orange. Limonene is a pleasantly citrus-smelling compound found in most citrus fruits such as oranges, lemons and limes. Limonene is an example of a terpene (see my quiz "Common names of Organic Molecules II"). Limonene is used as a solvent in degreasing metals prior to industrial painting, for cleaning in the electronic and printing industries, and in paint as a solvent. It is also used as a flavour and fragrance additive in food, household cleaning products, and perfumes. It can be easily obtained from most citrus fruits by steam distillation.
chocolate. Phenylethylamine belongs to a class of organic compounds called amines. Amines feature a nitrogen atom bonded to one or more carbon-based groups. Phenylethylamine is also produced naturally by the brain, and its effect is to produce a general sense of wellbeing or happiness. No wonder eating chocolate makes us happy! ;)
salt. Sodium chloride is common table salt. Sodium chloride (NaCl) is an ionic compound whose structure consists of a regular 3-dimensional lattice of sodium ions and chloride ions. Although the body needs sodium to function properly, too much salt in the diet can lead to fluid retention which in turn may lead to hypertension and stroke. Salt substitute can be purchased in some supermarkets: this is simply potassium chloride, which has the taste of sodium chloride, but no sodium ions.
|I am chopping some vegetables for dinner. This particular vegetable is making my eyes all teary due to the propanethial S-oxide it contains. Which vegetable am I chopping?||The Very Edible Organic Chemistry Quiz
onions. Onions contain a chemical called propanethial S-oxide, which is responsible for the tears you cry when chopping them. Chemical words containing "thia" or "thio" in them mean that they are sulphur-containing compounds. Many sulphur-containing compounds have particularly disagreeable smells (volatile sulphur-containing compounds are added in small quantities to natural gas so that you can smell it). It has recently been discovered that an enzyme in the onion is responsible for making propanthial S-oxide, and researchers have suggested that genetic modification may be the way to tear-free onions.
In the meantime, tips to reduce those tears when handling onions include slicing them under water and only slicing the top off the onion before chopping (the root apparently has the highest concentration of sulphur-containing compounds).
|My cake is now happily baking in the oven, but I am already hungry. I decide to go to the shop around the corner for some hot chips. When I bring them home, I sprinkle some dilute acetic acid on them before I eat them. What did I just put on my chips?||The Very Edible Organic Chemistry Quiz
vinegar. Acetic acid (chemical formula CH3COOH) is the major component of vinegar. Acetic acid belongs to the chemical family of carboxylic acids. These acids all contain an -OH group bonded directly to a carbonyl (C=O) group. Formic acid (found in ants) and butyric acid (found in your stomach) are other examples of carboxylic acids. Butyric acid is also what gives rancid butter its smell - in fact, the word "butyric" is derived from the Latin word "butyrum", meaning butter.
|I have almost finished the batter for my cake, but there's one more thing I have to add: I get a teaspoon and add some sodium bicarbonate to my batter. What have I just added?||The Very Edible Organic Chemistry Quiz
baking soda. Sodium bicarbonate (chemical formula NaHCO3) is what makes cakes rise. This is because when it's mixed with water, it forms carbon dioxide (CO2). These bubbles of carbon dioxide are what make the cake rise and give it a light texture. Self-raising flour has a small amount of sodium bicarbonate already added to it.
sugar. "Sugar" as we know it is the generic term given to sucrose. However, "sugar" is a term that is given to a whole range of compounds of a certain general structure that display sweetness as a physical property. More complicated sugars are all based on the linking together of small sugar units such as glucose. Sucrose is a disaccharide, which means that its structure is composed of two sugar units - in this case one unit of glucose and one unit of fructose.
Sucrose can be obtained from sugar cane (approx 20% by weight) or sugar beets (15% by weight).
6. Carbon has the atomic number 6, as a result of which its electronic configuration is (2,4), giving it its unique property of catenation- the cause of the wonderful world of organic chemistry!
Have a nice day!
| Carbon has the unique ability to form long chains with other carbon atoms. What name is given to a long chain consisting of many identical smaller molecules (called monomers)? ||Organic Chemistry for Beginners
Polymers. Plastics, like polythene (polyethylene) are all polymers. Polythene, for example, is formed by a chain containing a countless number of ethene (C2H4) molecules.
Another example of polymers are proteins, which are polymers of amino acids, said to be the 'building-blocks' of proteins.
|The tricky part of hydrocarbon-nomenclature is when you come across molecules with the same molecular formula, yet different structure! Even though such compounds have the same chemical formula, the arrangement of atoms within one molecule can be different, altering the properties completely! What are these compounds called? ||Organic Chemistry for Beginners
Isomers. For example, butane (C4H10) has 2 isomers- n-butane (butane) and isobutane (2-methyl propane).
And this is why we have to resort to IUPAC (International Union of Pure and Applied Chemistry) nomenclature... Note that here the names outside brackets are the 'common' names and those within brackets are IUPAC names.
|The common names of alkanes, alkenes and alkynes, all begin with certain prefixes, depending on the number of carbon atoms present in them. For example, when there is 1 carbon atom present, the prefix given is "meth-". When there are 2 carbon atoms, the prefix given is "eth-", and when there are 3 carbon atoms, the prefix "prop-" is attached. What is the prefix when there are *4* carbon atoms present?||Organic Chemistry for Beginners
but-. A simple table showing the relation between the number of carbon atoms present and the first part of the hydrocarbon name:
1 - meth-
2 - eth-
3 - prop-
4 - but-
5 - pent-
6 - hex-
7 - hept-
8 - oct-
9 - non-
10 - dec-
|Alkanes all have a certain 'general' or 'skeleton' formula: Suppose the number of carbon atoms in an alkane is 'n', what is the formula of that hydrocarbon?
(Hint: If you don't know the answer, take a look at the previous question!)||Organic Chemistry for Beginners
C(n)H(2n + 2). Let's verify this formula with the help of a couple of alkanes:
Here, n = 1
& (2n + 2) = 2*1 + 2 = 4
Here, n = 2
& (2n + 2) = 2*2 + 2 = 6
methane. Methane is a gas at room temperature, and is the principal component of natural gas, usually found in petroleum fields. The burning of methane produces little pollution, and hence the use of methane as a fuel, in the form of bio-gas, is encouraged. Bio-gas is particularly popular in rural areas of Denmark and the Netherlands, and is manufactured by the decomposition of organic plant and animal waste by anaerobic microbes.
Methane is also called the 'marsh gas', as it is formed in marshy or swampy areas, where organic matter is left to decay.
It is, however, a strong green-house gas, having the ability to cause 22 times the amount of warming done by carbon dioxide. It is also the the primary gas released along with carbon dioxide and sulphur compounds during...er...flatulation!
|Moving on to open-chain hydrocarbons now- in saturated hydrocarbons is it true that all the bonds between carbon atoms are single bonds only?||Organic Chemistry for Beginners
Yes. In saturated hydrocarbons, only single bonds exist between two carbon atoms, there aren't any double or triple bonds. Saturated hydrocarbons are more commonly known as 'alkanes'. The names of all alkanes and with the suffix "-ane", such as 'methane', 'ethane', and 'propane'.
At standard temperature and pressure (273.15 K temperature and 1 atm pressure), CH4 to C4H10 alkanes are gaseous; from C5H12 to C17H36, they are liquids; and after C18H38, they are solids.
|As is obvious from the name, 'hydrocarbons' are compounds which contain only carbon and hydrogen. Hydrocarbons are of two types- open-chained and close-chained, of which open-chained hydrocarbons are more commonly found.
Close-chained (or cyclic) hydrocarbons containing alternating single and double bonds are generally known to have intense smells, which led to this class of compounds being given a special name. What is this name?||Organic Chemistry for Beginners
Aromatic hydrocarbons. Ever heard of benzene (C6H6)? Benzene is the simplest possible aromatic hydrocarbon, and consists of 6 carbon atoms arranged in a hexagonal shape, with a hydrogen atom bonded with each of the carbon atoms. The bonds between the carbon atoms are alternately single and double bonds. The structure of a benzene molecule is called a 'benzene ring', because, like I said before, the carbon atoms have formed a kind of hexagonal ring.
Open-chain hydrocarbons are 'aliphatic hydrocarbons'.
|Amino acids are essential to life in that they are what make up proteins. Without proteins, the world as we know it would be a barren, lifeless entity. Amino acids can "join" together to form chains of amino acids. What is the bond that is formed between two amino acids specifically called?||Organic Chemistry and Functional Groups
Peptide Bond. A peptide bond is what allows amino acids to form dipeptides and polypeptides. The bond is represented by CO-NH where the carbon to oxygen bond is formed from the carboxyl group (R-COOH) of one amino acid and the nitrogen to hydrogen bond from the amine group (R-NH2) of the other amino acid. Amino acids include glycine, alanine and phenylalanine the latter of which contains a conjugated benzene ring.
I hope you enjoyed the quiz and thanks for playing!
|Many of the series of compounds that constitute the field of organic chemistry contain the same functional group. The group in question is 'C=O' which is essentially a double carbon to oxygen bond with two side groups attached to the carbon atom. What is the name of this functional group?||Organic Chemistry and Functional Groups
Carbonyl Group. The carbonyl functional group is present in, amongst other compounds, aldehydes, ketones, esters, carboxylic acids and amides. The carbonyl group is easily detected by the use of modern spectroscopic methods particularly nuclear magnetic resonance (NMR) and infrared spectroscopy (IR). In IR spectroscopy the C=O group is distinguished by a spread between 1600-1900 wavenumbers (though there is variation in these statistics). The peaks and spreads are brought about by the absorption of light in the infrared division of the electromagnetic spectrum.
|Organic chemistry is known for its complicated diagrams and also for its many mechanisms. What type of reaction has taken place if chlorobenzene (C6H5Cl) has been synthesised from an initial molecule of benzene (C6H6)?||Organic Chemistry and Functional Groups
Electrophilic Substitution. The chlorination of benzene to form chlorobenzene is achieved by reacting chlorine (Cl2) with benzene in the presence of a catalyst of iron, aluminium or their respective metal halides. As the diatomic chlorine approaches the stable benzene ring it becomes polarised and one of the chlorine atoms develops a partial positive charge. This is known as an electrophile and in this case an electrophile will react with the delocalised electron cloud of benzene. It is a substitution reaction rather than an addition because an atom of hydrogen on the benzene molecule is substituted by the chlorine. This reaction can also take place with another halogen, bromine. For those, like myself, who prefer the inorganic side of chemistry, hydrochloric acid (HCl) is given off as a by-product.
|Organic chemistry is really a series of connections and there is often more than one way to synthesise a particular compound. The answer to this question is one such example. You can reduce a carboxylic acid to a primary alcohol and you can oxidise that primary alcohol back to a carboxylic acid. However, what organic compound do you get when you react a carboxylic acid with an alcohol?||Organic Chemistry and Functional Groups
Ester. When a carboxylic acid reacts with an alcohol in the presence of some concentrated sulfuric acid (H2SO4), an ester (R-COO-R') is formed with a by-product of water. This reaction is an equilibrium which is why it is reversible. An ester can be hydrolysed back to an alcohol and a carboxylic acid or carboxylate salt with the use of both an acid and a base. In acid hydrolyis of an ester a carboxylic acid is formed with concentrated sulfuric acid as the catalyst and in base hydrolysis a carboxylate salt is formed by the use of sodium hydroxide as the catalyst (NaOH). An ester can also be formed by reacting an acid chloride with an alcohol or phenol.
|A carboxylic acid can be used to derive many different organic molecules. For example, a primary alcohol such as ethanol can be synthesised by reducing a carboxylic acid. What is the essential reducing agent used in this organic reaction?||Organic Chemistry and Functional Groups
Lithium Aluminium Hydride. There are two main reducing agents used in reduction reactions in organic chemistry and they are lithium aluminium hydride (LiAlH4) and sodium tetrahydridoborate (NaBH4). In this case however only LiAlH4 can be used as sodium tetrahydridoborate is not reactive enough to successfully do the job of reduction. There are a few conditions that need to be satisfied with the use of LiAlH4 which include the need for the reduction reaction to take place in dry ether. This is necessary because LiAlH4 is highly reactive with water. The formula for the alcohol series is R-OH (-OH is the hydroxyl functional group) with methanol having the formula CH3OH and ethanol, C2H5OH.
Potassium dichromate, which must be acidified, is used for the opposite oxidation reaction which synthesises a carboxylic acid from a primary alcohol. Concentrated sulfuric acid and concentrated nitric acid are needed to form a nitronium ion (NO2+) for use in the nitration of benzene.
|The carboxyl group (R-COOH or R-CO2H) is one of the two functional groups that is present on the building blocks of protein, amino acids. The second functional group on an amino acid is the amine group (R-NH2) and this along with the carboxyl group allows an amino acid to exist as a what?||Organic Chemistry and Functional Groups
Zwitterion. The existence of an amino acid as a zwitterion allows the constituents of protein to be used as a buffer which keeps pH constant in a variety of chemical environments. It can be used as a buffer due to the presence of the two functional groups mentioned above, the carboxyl group and amine group. The carboxyl group is acidic and by definition is a proton (H+) donor and the amine group is basic and is a proton (H+) acceptor. Therefore, if a base (OH-) is added to the chemical solution, the amine group (which in zwitterion form is NH3+ as it has accepted a proton) reacts with the base to form water which is neutral. This results in the pH remaining the same. The same takes place when an acid (H+) is added to a solution. The carboxyl group (in zwitterion form is COO- as it has donated a proton) reacts with the acid to again form water maintaining pH levels.
|In organic chemistry, the reactions of many molecules are dependent upon the functional group. The functional group can also affect physical properties. What characteristic of a carboxylic acid gives the molecule a much higher boiling point than many other molecules of similar molecular weight?||Organic Chemistry and Functional Groups
Hydrogen Bonding. Carboxylic acids are commonly written in short as R-COOH or R-CO2H, where R stands for an alkyl chain/group (hydrocarbon chain/group). A simple laboratory test for the presence of a carboxyl group in a compound is to react the compound with sodium hydrogen carbonate (NaHCO3) or sodium carbonate (Na2CO3). If the carboxyl group is present effervescence of carbon dioxide (CO2) will take place. To ensure that the gas evolved is indeed carbon dioxide, run the gas through lime water which will turn milky.
Carboxylic acids have higher boiling points than would be expected by the hydrogen bonding present. Hydrogen bonding is the bond between an atom of hydrogen with another atom of either oxygen, nitrogen or fluorine. In the case of R-COOH two hydrogen bonds can occur between two of the molecules which raises the boiling point.
|What does the fact that alcohols react with highly reducing metals (such as sodium) prove?||Organic Chemistry 101
alcohols are acidic. Since the hydrogen in the alcohol's hydroxyl group is switched with a metal, the alcohol acts as a hydrogen ion donor, which is exactly how acids work. The result of the above mentioned process are alkoxides, conjugate bases of alcohols.
Conjugate bases of weak acids are strong (and vice versa), so alcohols, being weak acids their alkoxides are strong bases.