1-Octanamine, N,N-dimethyl-, N-oxide

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: data from peer-reviewed article / authoritative report

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

Estimation using the ratio of the solubility in n-octanol to water

Type of method:

estimation method (solubility ratio)

Specific details on test material used for the study:

Commercial amine oxides are either alkyl dimethyl amine oxides or alkyl dihydroxyethyl amine oxides which contain 2 methyl groups or 2 hydroxyethyl groups, respectively, attached to the tertiary nitrogen. Alkyl chain lengths range from 8 to 20 with 12 and 14 being predominant. The justification for grouping the amine oxides into a category is based on their structural and functional similarity. All of the substances in this category are surfactants, consisting of a polar “head” (the amine oxide) and a relatively inert, hydrophobic “tail” (the long alkyl substituent). The structural variations in the category are three-fold: 1) the nature of the second and third substituents on the amine are either methyl groups or hydroxyethyl groups; 2) the long alkyl chain ranges in length from 8 to 20 carbons; and 3) the long alkyl chain may contain one or two double bonds (i.e. unsaturation) as in C18:1 (oleyl) or C18:2 (linoleyl).

Key result

Type:

log Pow

Partition coefficient:

< 2.7

Remarks on result:

other: temperature and pH not reported

Details on results:

Accurate measurement of surfactant partitioning is challenging due to their amphoteric nature. Although a measured log Kow value exists for C10-C16 amine oxides, with a result of -1.08 (OECD, 2006), the accurate measurement of octanol-water partitioning for surface active substances is difficult because they tend to accumulate at the octanol/water interface, forming octanol-water emulsions. Log Kow values ranging between 0.95 and 2.7 have also been predicted by comparing published critical micellar concentration (CMC) values of C10-C14 amine oxides in water, with measured octanol solubility values (CMCs can be considered as a conservative measure of water solubility for surface active substances). Thus, amine oxides with alkyl chain length less than C14 can be considered as having log Kow <2.7. Consequently, based purely on hydrophobicity, amine oxide chain lengths less than C14 are expected to have a low potential to bioconcentrate (BCF < 87 L kg−1; OECD, 2006).

Conclusions:

Amine oxides with alkyl chain length less than C14 can be considered as having a log Kow < 2.7.

Executive summary:

Amine oxides with alkyl chain length less than C14 can be considered as having a log Kow < 2.7.

Reference 2

Endpoint:

partition coefficient

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: data from peer-reviewed publication / authoritative report

Justification for type of information:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Read-across hypothesis: "Different compounds have the same type of effect(s)"

2. SOURCE AND TARGET CHEMICAL(S)
- Target chemical: 1-Octanamine, N, N-dimethyl-, N-oxide (CAS RN 2605-78-9)
- Source chemicals = members of the amines oxides category defined in Amine Oxides - SIDS Initial Assessment Report for SIAM 22 and SIDS Dossiers (OECD, 2006):
**1-Dodecanamine, N,N-dimethyl-, N-oxide (CAS RN 1643-20-5)
**1-Tetradecanamine, N,N-dimethyl-, N-oxide (CAS RN 3332-27-2)
**Amines, C10-16-alkyldimethyl, N-oxides (CAS RN 70592-80-2)
**Amines, C12-18-alkyldimethyl, N-oxides (CAS RN 68955-55-5)
**Decanamine, N,N-dimethyl-, N-oxide (CAS RN 2605-79-0)
**Hexadecanamine, N,N-dimethyl-, N-oxide (CAS RN 7128-91-8)
**Octadecanamine, N,N-dimethyl-, N-oxide (CAS RN 2571-88-2)
**Amine oxides, cocoalkyldimethyl (CAS RN 61788-90-7)
**Amines, C10-18-alkyldimethyl, N-oxides (CAS RN 85408-48-6)
**Amines, C12-16-alkyldimethyl, N-oxides (CAS RN 85408-49-7)
**Ethanol, 2,2'-iminobis-, N-coco alkyl derivs., N-oxides (CAS RN 61791-47-7)
**Ethanol, 2,2'-(dodecyloxidoimino)bis- (CAS RN 2530-44-1)
**Ethanol, 2,2'-(octadecyloxidoimino)bis- (CAS RN 14048-77-2)
**Ethanol, 2,2'-iminobis-, N-tallow alkyl derivs., N-oxides (CAS RN 61791-46-6)
**Ethanol, 2,2’-[(9Z)-9-octadecenyloxidoimino]bis- (CAS RN 93962-62-0)

3. ANALOGUE APPROACH JUSTIFICATION
As reported in the Amine Oxides - SIDS Initial Assessment Report for SIAM 22 and SIDS Dossiers (OECD, 2006): "The justification for grouping the amine oxides (AO) is based on their structural and functional similarity. All of the substances in this group are surfactants, consisting of a polar “head” (the amine oxide) and a relatively inert, hydrophobic “tail” (the long alkyl substituent). The structural variations in the group are three-fold: 1) the nature of the second and third substituents on the amine are either methyl groups or hydroxyethyl groups; 2) the long alkyl chain ranges in length from 8 to 20 carbons; and 3) the long alkyl chain may contain one or two double bonds (i.e. unsaturation) as in C18:1 (oleyl) or C18:2 (linoleyl). Alkyl chain lengths range from 8 to 20 with 12 and 14 being predominant. Average chain lengths for the mixtures are 12.9 to 13.5, with the exception of one tallow-derived compound. The presence of methyl- vs. hydroxyethyl-substituents affects the basicity of the nitrogen only marginally, and the hydroxyethyl group lends more bulk to the hydrophilic head-group of the surfactant. The length of the longest alkyl substituent does not alter the chemical reactivity of the molecule, but does affect its physical properties."

4. PHYSICO-CHEMICAL DATA
As reported in the Amine Oxides - SIDS Initial Assessment Report for SIAM 22 and SIDS Dossiers (OECD, 2006): "Amine oxides do not exist as ‘pure’ substances, but are produced, transported and used as aqueous solutions, typically within a range of 25-35% AO/water. Experimental values for melting points of C10 to C16 amine oxides range from 125 to 136°C. Amine oxides undergo Cope elimination, i.e., the formation of an olefin and a hydroxylamine by pyrolysis of an amine oxide, in the temperature range 150-200°C, thus decomposition is likely to occur before the melting point is reached, and all boiling points are predicted to be far above the decomposition temperature. Amine oxides are not volatile: predicted vapor pressure values are < 4.6E-7 hPa. Amine oxides are highly water soluble – measured values for a C12.6 average chain length is ~410g/L. Although it is impossible to accurately measure an octanol-water partition coefficient for surface-active agents like amine oxides, an octanol-water partition coefficient (Log value) of < 2.7 has been calculated for amine oxides of chain length C14 and below."

Reason / purpose for cross-reference:

read-across: supporting information

Key result

Type:

log Pow

Partition coefficient:

< 2.7

Remarks on result:

other: temperature and pH not reported

Conclusions:

Amine oxides with alkyl chain length less than C14 can be considered as having a log Kow < 2.7.

Executive summary:

Amine oxides with alkyl chain length less than C14 can be considered as having a log Kow < 2.7.

Description of key information

As no data were available to characterize the n-octanol/water partition coefficient of 1-Octanamine, N, N-dimethyl-, N-oxide, a read-across approach was followed to fill in the endpoint. The read-across approach was based on an analogy with members of the amine oxides category defined in Amine Oxides - SIDS Initial Assessment Report for SIAM 22 and SIDS Dossiers (OECD 2006). According to the information collected for the category definition, amine oxides with alkyl chain length less than C14 can be considered as having a log Kow < 2.7.

Additional information

The n-octanol/water partition coefficient log10 Pow of 1-Octanamine, N, N-dimethyl-, N-oxide was estimated from data available on similar substances. The read-across approach is considered as reliable with restrictions (Klimisch 2) and is selected as a key study for the endpoint.