The Story Behind Ester...

Ester

Esters are derived from a carboxylic acids and an alcohol. Glycerides, which are fatty acid esters of glycerol, are important esters in biology, being one of the main classes of lipids, and making up the bulk of animal fats and vegetable oils. Esters with low molecular weight are commonly used as fragrances and found in essential oils and pheromones. 

Three basic preparation methods of ester.

Esters are usually prepared from acids.
1. Reaction of a carboxylate anion with a primary alkyl halide via SN2 reaction.
2.Fischer esterification. Heat a carboxylic acid in an alcohol solvent containing a small amount of strong acid catalyst produces an ester from the alcohol and carboxylic acid.
3.Alcoholysis. Acid chlorides react with alcohols in the presence of pyridine or NaOH to get esters. The reaction is better with less steric bulk.

Reaction of Esters

1. Hydrolysis (Conversion of Esters into Carboxylic Acids)
Esters are hydrolysed by aqueous base (saponification) or aqueous acid (reverse of Fischer Esterification), to yield carbocxylic acids plus alcohols. 

2. Aminolysis ( Conversion of Esters into Alcohols)

Esters react with ammonia and amines to yield amides. The reaction is not often used, however, because higher yields are normally obtained by aminolysis of acid chlorides.

3. Reduction ( Conversion of Esters into Alcohols)

Esters are easily reduced by treatment with LiAIH4 to yield primary alcohols.

4. Reaction of Esters with Grignard Reagent

Esters react with 2 equivalents of a Grignard reagent (RMgX) to yield a tertiary alcohol. The reaction occurs by the usual nucleophilic substitution mechanism to give an intermediate ketone, which reacts further with Grignard reagent to yield a tertiary alcohol.

Facts 

The key feedstock required in the production of fatty acid esters includes vegetable oils such as palm oil, sunflower oil and rapeseed oil among others. Growing demand for esters from cosmetics, lubricants, paper and personal care industry is expected to drive the market growth. Fatty esters are used in cosmetics products as a replacement of petroleum products.These are derived from vegetable oils and other renewable raw materials, hence human health hazards of fatty esters are claimed to be null. Demand for fatty acid based cosmetic products in Asia Pacific is expected to fuel the market growth.                                          

Properties and Uses of Esters

Esters are not soluble in water and have a very pleasant smell. Smaller ones are quite volatile (evaporate easily) and are used in adhesives, inks and paints. Pentyl ethanoate is used in nail varnish. Many esters are used in flavourings and in perfumes.

Natural fruit flavours also contain blends of esters. Some common esters in fruit are:

Ester	Fruit
Pentyl ethanoate	Banana
Octyl ethanoate	Orange
Methyl butanoate	Pineapple
3-Methylbutyl butanoate	Apple

Which industries might use synthetic esters? Why?

Food Industry   

 -Flavouring food in particular of lollies & sweets. Also margarine & preservatives.

Cosmetic Industry 

-Create nice smelling perfumes and add pleasant aromas to other products such as shampoo and lotions.

Beverage Industry

-To give drinks nice flavours such as cordials.

Alcohol Industry

-Again to add flavour. Most obviously the uses such as Propyl-2-methylpropanoate in Rum.

Medicines

-Especially children's medicines to add nice fruity flavours.

Clothing Industry 

-Synthetic fibres such as polyester.

 Energy Industry

-Such as to make biodiesel fuels.

Mechanical Industry

-Such as use as lubricants on machinery.

Going in 'Organic Chemistry', A Quick Q&A.

Organic Chemistry

- Study of the structure, properties, composition, reactions, and preparation of carbon-containing compounds (not only hydrocarbons but also compounds with any number of other elements, including hydrogen, nitrogen, oxygen, halogens, phosphorus, silicon, and sulfur. 

- Originally limited to compounds produced by living organisms but has been broadened to include human-made substances such as plastics. 

- The range of application of organic compounds is enormous and also includes, but is not limited to, pharmaceuticals, petrochemicals, food, explosives, paints, and cosmetics.

Quick Q&A

1. First thought about organic chemistry.

Carbon. 

2. 4 groups of organic compounds.

Carbohydrates, proteins, lipids and nucleic acids. 

3. Functional groups?

Part of the molecule which makes it ‘function’ the way it does.

4. Examples of functional groups.

Carboxylic acid, alcohol, aldehyde, ketone, ester, amide, amine. 

5. Hybrid orbitals of carbon compounds?

sp, sp², and sp³

^{6. Carbon-carbon bonding.}

Single, double, triple. Alkane, alkene and alkyne. 

7. Real-life application of organic chemistry.

Perfume, shampoo, medical drugs, soap. 

8. Bad effects of application of organic chemistry. 

Pesticides, polluting environment and bring harmful effects on human health if consumed. 

The Facts about Bisphenol A (BPA)

Bisphenol A (BPA) is a carbon-based synthetic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ which belongs to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. BPA is soluble in organic solvent but it is insoluble or poorly-soluble in water. It is a chemical substance that has been used to harden plastics for more than 40 years as BPA-based plastic product is clear and tough. Nowadays, when can see it everywhere from consumer goods to medical devices. For instance, water bottles, lining of canned foods and drinks and sports equipment.

In 2010, the issue of possible health risks of the Bisphenol A (BPA) became the headlines of media. In 2009, the United State Food and Drug Administration used to report that BPA was safe. However, the agency altered its stand in the year of 2010. They claimed that there are potential effects of BPA on the brain, behaviour and prostate glands in fetuses, infants, young children and adults. After the heated debate of this issues, the public authorities set BPA safety levels for those plastic manufacturers but many experts still believe these levels should be reviewed after certain studies were conducted.

So, how scientists say BPA could affecting our bodies?

• Eroding teeth
• In 2013, French researchers reported their result of studies which shown that the teeth of rats treated with low daily doses of BPA could be damaging tooth enamel. 
• By analyzing the characteristics of damage, they showed that the damages occurred to the tooth enamel of rats are common with a recently identified pathology of tooth enamel that affects about 18 percent of children with range of age at 6 to 8. These results have been reported in the American Journal of Pathology.

• Causing heart disease
• A 2011 animal study published in the journal PLOS One found BPA overrode the female body's natural heartbeat signaling, causing arrhythmia—erratic beating that could cause sudden cardiac death.
• The scientists of University of Cincinnati found that BPA can cause heart disease in women and adults
• People with higher levels of BPA in their urine are more likely to have heart disease than their counterparts.

• BPA is an endocrine distruptor
• It is an chemical that may interfere with the body's endocrine system and causes adverse developmental, neurological and immune effects in humans.
• Hormones have many modes of action which include the ability to initiate or suppress gene transcription and BPA interfere with those genetic-level processes which leave a great impact on fetuses and infants that have most vulnerability to the effect of BPA.
• This may leave the negative effect on the development of brains and distruption on gene regulation.

• Affecting the reproductive system
• BPA causes the distruption of developmental progression of reproductive system that permanently alter the organization of sexually dimrphic neuroendocrine circuits in the brain, timing of puberty, development of sex-typical behaviors and most importantly the capacity to reproduce.
• For male, rates of testicular cancer appear to be increasing whereas the sperm counts are decreasing. An analysis of about 100 research studies concluded that sperm counts in United States and Europe have a sharp declined of 50% over the past 50 years due to the exposure of BPA.
• For female, female fecundity is declining and the effects on oocyte quality and ovarian function in women is slightly affected. Carlifonian researchers found that exposure to BPA did affect the quality of woman's egg which causes higher risk of infertility and poor ovarian response.

We should protect ourselves by avoiding the BPA EXPOSURE, and here are some suggestions for you:

• Use food-grade stainless steel or glass container instead of using plastic food and drinks container.
• Store trivial receipts in an envelope and not in your wallet or purse to prevent frequent contact with the paper through your skin.
• Avoid microwaving food in plastic containers and do not use harsh detergents to clean a plastic container.
• Option for fresh vegetables and food instead of the canned one.
• Always be skeptical of BPA-free claims

Hope these information will be helpful for you! 

Sunscreen vs Sunblock, Which Suits Us More ?

There are two types of protective lotions – chemical and physical.

   

Sunblock, the physical kind, contains both organic and non-organic ingredients that sit on top of the skin acting as a barrier between your skin and damaging UV rays by reflecting or scattering UVB light. Look for products with octyl methoxycinnamate, octyl salicylate and octocrylene. In the past, you could tell who was using a sunblock just by looking, because the sunblock whited out the skin. Not all modern sunblocks are visible because the oxide particles are smaller, though you can still find the traditional white zinc oxide. 

Sunscreen, the chemical kind, penetrates the skin and absorbs the UVA rays before they are able to reach and damage your dermal layer. Like a screen door, some light penetrates, but not as much as if the door wasn't present. Zinc oxide and titanium dioxide are the active ingredients in deflecting harmful UV rays before they reach the protective outer epidermis layer of your skin. Another ingredient to look for is ecamsule, which is a photostable sun protectant that blocks out photoaging UVA rays. 

Sunblocks are formulated to shield against UVB rays, while sunscreens protect against UVA. In order to fully protect your skin, choose a broad-spectrum protection formulated sunscreen that will protect against both UVA and UVB rays (The “A” in UVA stands for ‘Aging’. The “B” in UVB stands for ‘Burning’). Luckily these days, formulas often contain a mixture of both sunblock and sunscreen.

What Sunscreens Screen ?

• UV-A penetrates deeply into the skin and can lead to cancer and premature skin aging.
• UV-B is involved in tanning and burning of your skin.
• UV-C is completely absorbed by the earth's atmosphere.
• PABA (para-aminobenzoic acid) absorbs UVB
• Cinnamates absorb UVB
• Benzophenones absorb UVA
• Anthranilates absorb UVA and UVB
• Ecamsules absorb UVA

What SPF Means ?

The portion of the sunlight that is filtered or blocked is ultraviolet radiation. There are three regions of ultraviolet light.

The organic molecules in sunscreen absorb the ultraviolet radiation and release it as heat.

SPF stands for Sun Protection Factor. It's a number that you can use to help determine how long you can stay in the sun before getting a sunburn. Since sunburns are caused by UV-B radiation, SPF does not indicate protection from UV-A, which can cause cancer and premature aging of the skin.

Your skin has a natural SPF, partially determined by how much melanin you have, or how darkly pigmented your skin is. The SPF is a multiplication factor. If you can stay out in the sun 15 minutes before burning,using a sunscreen with an SPF of 10 would allow you to resist the burn for 10x longer or 150 minutes.

Although the SPF only applies to UV-B, the labels of most products indicate if they offer broad spectrum protection, which is some indication of whether or not they work against UV-A radiation. The particles in sunblock reflect both UV-A and UV-B.

         

To Reapply or Not to Reapply?

Consider your personal needs and habits when deciding the best sun protectant. You may also need to consider your application depending on activity level. For instance, if you’ll be in the water or sweating a lot, it is best to reapply frequently. Sensitive skin may fare better with sunblock since titanium dioxide and zinc oxide are less irritating than some ingredients found in sunscreen.

Adding sunscreen to your daily routine can block UVA, promoting graceful aging and UVB, which can keep your skin from burning. With this new knowledge you can safely minimize your sun exposure risk and choose the right sunblock to best fit your lifestyle.

Is there a difference between "waterproof" and "water-resistant" ?

How well the sunscreen stays on the skin after swimming, bathing or perspiring is just as important as the SPF level. The FDA considers a product "water-resistant" if it maintains its SPF level after 40 minutes of water exposure. A product is considered "waterproof" if it maintains its SPF level following 80 minutes of exposure to water. If you participate in outdoor recreational activities including swimming, you may want to choose a waterproof sunscreen.

The Bottom Line on Sunblock vs Sunscreen:

1. Most lotion is a combination of both sunblock and sunscreen, so read the ingredients carefully if you are needing a pure sunblock.

2. Be sure to look for a sunblock or sunscreen that does NOT contain vitamin A and its derivatives, retinol and retinyl palmitate, as this may speed up the cancer that sunscreen is used to prevent.

3. Be sure to check the Environmental Working Group’s searchable database of all sunblocks and sunscreens before headed to the store to find the ones safest and most effective for you and your family.

WILL ONE BAD APPLE RUIN THEM ALL ?

You've heard that 'one bad apple spoils the whole barrel', right? It's true. Bruised, damaged, or overripe fruit gives off a hormone that accelerates the ripening of the other fruit -- ETHYLENE.

What is ETHYLENE ?

Ethylene (C2H4, also known as ethene) is a gaseous organic compound that is the simplest of the alkene chemical structures (alkenes contain a carbon-carbon double bond).  Ethylene is the most commercially produced organic compound in the world and is used in many industrial applications. 

Plant tissues communicate by means of hormones. Hormones are chemicals that are produced in one location that have an effect on cells in a different location. Ethylene is the hormone that will cause a wide range of effects in plants, such as fruit ripening, loss of chlorophyll, abortion of plant parts, stem shortening, abscission of plant parts, and epinasty (bending of stems) which  depending on the age of the plant and how sensitive the plant is to ethylene. Ethylene can be either good or bad, depending on what merchandise you work with. It is used in a positive manner in fruit ripening, for instance. It can also cause damage in crops. Examples of damage might include yellowing of vegetables, bud damage in dormant nursery stock, or abscission in ornamentals (leaves, flowers drop off). Most plant hormones are transported through the plant vascular system, but some, like ethylene, are released into the gaseous phase, or air.

                                         

Where does it come from?

Ethylene is produced and released by rapidly-growing plant tissues. It is released by the growing tips of roots, flowers, damaged tissue, and ripening fruit. The hormone has multiple effects on plants. One is fruit ripening. When fruit ripens, the starch in the fleshy part of the fruit is converted to sugar. The sweeter fruit is more attractive to animals, so they will eat it and disperse the seeds. Ethylene initiates the reaction in which the starch is converted into sugar.

Commercial Use of Ethylene to Ripen Fruit

Climacteric fruits are frequently harvested at a physiological stage that is considered ‘commercial maturity’, typically in a hard green but mature stage just before ripening has initiated.  Examples include bananas, mangoes, tomatoes and avocados.  This enables the fruit to be harvested, cooled, stored and transported significant distances to where it will be marketed and consumed.

Ripening can then be conducted under controlled conditions of temperature, relative humidity and ethylene to achieve uniform appearance and quality of ripe fruit.  Fruit is placed into specially constructed ripening rooms and brought to optimum ripening temperature and humidity.  Ethylene is then raised to a prescribed concentration using either a "catalytic generator" that makes ethylene gas from liquid ethanol or from commercially available gas supplies.  Forced-air cooling systems ensure that fruit are uniformly exposed to the room ethylene concentration.  When fruit are exposed to ethylene under these controlled conditions they will initiate their respiratory climacteric pattern and ripen at a relatively uniform rate.  Conditions and duration can be varied to suit customer specifications for stage of ripening and colour development.

However, concerns are periodically raised in mass media about fruit being ‘gassed’, implying that this confers some residual food safety risk from the ethylene gas and that the fruit has been somehow rendered ‘unnatural’.  The public should understand that the commercial use of ethylene for fruit ripening is at a low concentration and simply initiates the respiratory climacteric.  The ethylene used commercially has the same molecular structure.  By the time the ethylene-treated fruit reaches the consumer the climacteric may have started, there is no trace of applied ethylene gas, any ethylene emitted by the fruit is generated by the fruit itself and is of a much greater concentration.  Therefore, there are no food safety issues associated with the consumption of climacteric fruit.