What are esters?
esters are chemical compounds derived from an acid (organic or inorganic) in which at least one -OH (hydroxyl) group is replaced by an -O-alkyl (alkoxy) group.The chemical formulas of organic esters usually take the form RCO2R', where R and R' are the hydrocarbon parts of the carboxylic acid and the alcohol, respectively. For example, butyl acetate (systematically butyl ethanoate), derived from butanol and acetic acid (systematically ethanoic acid) would be written CH3CO2C4H9. Alternative presentations are common including BuOAc and CH3COOC4H9.Esters contain a carbonyl center, which gives rise to 120 °C-C-O and O-C-O angles. Unlike amides, esters are structurally flexible functional groups because rotation about the C-O-C bonds has a low barrier. Their flexibility and low polarity is manifested in their physical properties; they tend to be less rigid (lower melting point) and more volatile (lower boiling point) than the corresponding amides.The pKa of the alpha-hydrogens on esters is around 25.Esters are widespread in nature and are widely used in industry. In nature, fats are, in general, triesters derived from glycerol and fatty acids. Esters are responsible for the aroma of many fruits, including apples, durians, pears, bananas, pineapples, and strawberries. Several billion kilograms of polyesters are produced industrially annually, important products being polyethylene terephthalate, acrylate esters, and cellulose acetate.Esters react with nucleophiles at the carbonyl carbon. The carbonyl is weakly electrophilic but is attacked by strong nucleophilies (amines, alkoxides, hydride sources, organolithium compounds, etc.). The C-H bonds adjacent to the carbonyl are weakly acidic but undergo deprotonation with strong bases. This process is the one that usually initiates condensation reactions. The carbonyl oxygen is weakly basic (less so than in amides) but forms adducts.
What is the functional group of Ester?
Ester is an organic compounds in which the acidic hydrogen (the one attached to oxygen of carboxyl carbon) of an carboxylic acid by an alkyl group. It has general formula same as carboxylic acids i.e. [math]C_nH_{2n}O_2[/math]. Its functional group is denoted as ‘-COOR’. In IUPAC nomenclature, they are named as Alkyl alkanoate.It can be prepared by reacting carboxylic acid with alcohol in presence of concentrated sulphuric acid as a dehydrating agent. Eg.[math]\underbrace{CH_3COOH}_{\text{Ethanoic acid}} + \underbrace{C_2H_5OH}_{\text{Ethanol}} \xrightarrow{conc.H_2SO_4} \underbrace{CH_3COOC_2H_5}_{\text{Ethyl ethanoate}} + H_2O[/math]
Draw The Functional Groups: Ether, Ester, Alcohol? Help???
You should be able to find this in ANY chemistry text, but I will describe them to you. The functional group for an alcohol is - OH, for an ether - O -, and for an ester it is a carbonyl group in which the C is also covalently bonded to an alkyl group and an oxanoic acid group. The functional group thus looks like this - C - O - II O Best wishes...
Biodiesel are mono-alkyl esters?
what does "mono" stands for? is it refer to structure of alkyl esters having only one alkyl group? or it means that the resulting ester is made only of one alkyl esters then, which statement is correct" 1. mixture of methyl ester and ethyl esters cannot be considered biodiesel because it is poly-alkyl esters or 2. isopropyl ester cannot be considered biodiesel because its structure contains three alkyl gropu attached to carboxylate carbon isopropy
What does alkyl means?
An alkyl is a univalent radical containing only carbon and hydrogen atoms arranged in a chain. The alkyls form a homologous series with the general formula CnH2n+1. Examples include methyl, CH3· (derived from methane) and butyl C4H9· (derived from butane). They are normally not found on their own but are found as part of larger branched chain organic molecules. On their own they are free radicals and therefore extremely reactive. The structure of an alkyl is the same as its straight chained alkane counterpart but with one less hydrogen atom. For example, this is the structure of methyl, the smallest alkyl: Alkyls are radicals since only three out of four valency electrons are used in bonding on one of the carbon atoms. A secondary alkyl group is branched with the central carbon atom linked to two carbon residues. Likewise in tertiary alkyl groups there are three carbon linked substituents. In neopentane the central carbon atom is quaternary.
Phenols are more acidic than alcohol? Why?
Phenols are more acidic than alcohols:An acidic substance is something that can produce a hydrogen (H+) when in water.However both alcohols and phenols are weak acids , the alcohols are less acidic then phenols because it is very tough to remove the H ion from alcohol.Phenol can lose ion easily because phenoxide ion formed is stabilised to some extent,This is as the negative charge on the oxygen atom is delocalised around the ring i.e having a cyclic structure in phenol helps it stay stable even after hydrogen is removed.Delocalized charge means negative charge is distributed almost equally through the compounds.The more stable ion is,the more likely it is to form .In this case phenol,the alcohol is almost similar to being non charged even after the hydrogen ion is removed and thus can have some acidic effect.
Why do grignard reagents only react with carbonyl group?
Grignard reagents are nuccleophylic because they are basically an alkyl anion bonded to a magnesium ion (the other anion is usually bromide or iodice). This negative alkyl group is attracted to the partially positive carbon of the carbonyl group (remember carbonyl groups are polar: partially negative oxygen and partially positive carbon. The carbon atoms on the remainder part of the carbonyl compound ( the normal hydrocarbon hydrogens) are not polar, so they do not have a partial charge to attract the negative alkyl group that the Grignard has. It also will not react with the normal hydrocarbon carbons for the same reason (they are not polar.)
Can we protect the carboxyl group of oxocarboxylic acid to form an ester without decarbonylation?
Generally this is not a concern unless the two carboxylic acids to be esterified are attached to the same carbon. In principle, it is a problem for the latter type of dicarboxylic acid as these compounds are known to decarboxylate at high temperature. The key here is ‘high temperature’ and the typical conditions for esterification of a dicarboxylic acid to meet the ‘high temperature’ metric. For example, diethylmalonate is made from malonic acid by treating the latter with ethanol and sulfuric acid at reflux as shown below:This basic approach and various modification (e.g., running the reaction in the presence of molecular sieves to remove the water, other acid catalysts, etc.) all result in a yield of about 80% +/- 10%, typical of an average, useful, synthetic reaction.
Hydrocarbons and functional groups?
In a word YES!!! It would be a very large carbon branched molecule.. HOH2C-CH(F)-CH(Cl)-CH(Br)-CH(I)-CH(CH2... = CH-CH(CHO)- C(=O)-COOH From left to right Alcohol (Written backward) Fluoride Chloride Bromide Iodide Ethyl (Alkyl) Ethene Branched aldehyde ketone Carboxylic acid . I hate to think what the modern IUPAC name for such a molecule would be !!! If you lengthened the chain and put in more branches you could include ethers, esters, anhydrides, acid halides., amides, amines, imines, thiols, I could go on. !!! In organic chemistry and biochemistry there are some very large protein molecules with lots of different functional groups attached. Using the old style names. Here are some molecules with between 11 to 20 carbons in the chain. Palmitic acid Stearic Acid Linoleic acid. The first two are for soap making. Organic (Carbon) chemistry is very large and complex , there are though to be some 5 billion ( 5,000,000,000 ) ( 5x 10^9) carbon Organic molecules.
Is NH2 a functional group?
Yes, -NH2 is a functional group!This group is also called as the amine or the amino group. This group is obtained by replacing one atom hydrogen of the ammonia molecule by an aryl group or an alkyl. There are two kinds of NH2 functional groups, namely Aliphatic R-NH2 and Aromatic Ar-NH2.